Sixty years of Shisha Bangma
Wu Fuyuan
Xisha Bangma, a peak above 8000 m (8027 m) located entirely in China. On May 2, 1964, 10 mountaineers from the Chinese mountaineering team successfully climbed to the summit of Xixia Bangma Peak. This is the first feat of human conquest of this peak, and thus it has left a strong mark in the history of mountaineering in the world. The scientific expedition that accompanied this mountaineering activity also yielded fruitful results. In particular, the discovery of the fossil of Quercus alpine in the 5800 m camp has opened a precedent for the study of the uplift of the Qinghai-Tibet Plateau in the mainland, thus making the Xixia Bangma a glorious monument in the study of mainland geology. Today marks the 60th anniversary of the ascent of Shisha Bangma, and Acta Petrologica Sinica has published an album to commemorate this important historical moment. The special editors of the album are Wang Jiamin, associate researcher of the Institute of Geology and Geophysics, Chinese Academy of Sciences, and Professor Su Tao of Chengdu University of Technology.
1 Scientific expedition to the Shisha Bangma
The 50s of the 20th century was the most active era in the history of mountaineering in the world. On May 29, 1953, New Zealand mountaineer Edmund Percival Hillary and Nepalese mountain guide Tenzing Norgay successfully reached the summit of Mount Everest. Prior to this, only Annapurna (8091 m, the world's 10th highest peak) in Nepal was conquered by a French mountaineering team in 1950 of the world's 14 peaks above 8000 m. Inspired by the successful ascent of Mount Everest, mountaineers from all over the world have launched one attack after another on the world's highest peaks. By the end of 1960, with the exception of the Shisha Bangma Peak, which was located entirely on the mainland, the peaks above 8,000 m on Earth had been conquered by humans. Affected by this international situation, on the basis of the successful summit of Mount Everest by mainland mountaineers in 1960, the State Sports Commission began to plan for the summit of Xixia Bangma Peak.
In 1964, the Chinese mountaineering team climbed the peak of Xixia Bangma. On May 2, 10 mountaineers of the Chinese mountaineering team (Xu Jing, Zhang Junyan, Wang Fuzhou, Wu Zongyue, Chen San, Sonam Dorjee, Cheng Tianliang, Nima Tashi, Dorjee and Yundeng) successfully climbed the peak of Xixia Bangma Peak, marking that all the peaks above 8000 m on the earth have been conquered by humans. As a result, this mountaineering activity had a wide and enthusiastic impact on Chinese society at that time.
In order to cooperate with the Chinese mountaineering team to climb Xixia Bangma Peak, the Chinese Academy of Sciences and the State Sports Commission organized a scientific expedition team of the Chinese Xixia Bangma Peak Mountaineering Team with Shi Yafeng and Liu Dongsheng as the principal and deputy team leaders, which is divided into four professional groups: surveying, glaciology, geology, geomorphology and Quaternary geology. The survey group has Zhou Jiqing, Yu Jilian, Zhu Desheng, Xie Zichu, Ji Zhixiu, Huang Maoheng in the glacier group, Xiong Hongde, Zhang Kangfu, Wang Xinping, Zhang Mingliang in the geological group, and Cui Zhijiu and Zheng Benxing in the geomorphology and quaternary geology group, a total of 14 people (and 1 driver). On January 24, 1964, Liu Dongsheng and others set off from Beijing to start the Xixia Bangma scientific expedition. On March 5, Liu Dongsheng and four members of the geological team of the scientific expedition team left Lhasa for Xixia Bangma, arrived at Dingri on March 8, arrived at the Xixia Bangma Mountaineering Base Camp on March 28, left the base camp on May 8 to carry out investigation along the Nyalam line, left Lhasa on May 24 to go to Golmud, Lanzhou and Xi'an, and then returned to Beijing, and the field work of Xixia Bangma scientific expedition officially ended. The field work lasted more than two months. But if you count the time on the road, the entire expedition lasted more than four months.
During the mountaineering period of the Chinese mountaineering team, the geological team of the scientific expedition team conducted a large number of route investigations along the Dingri-Nyalam route and the area north of the 5800 m camp of Xixia Bangma (Pengqu-Nakdora River-Yebokanggale Glacier), and obtained a large number of first-hand information. The relevant results published during the data summary period (Shi Yafeng and Liu Dongsheng, 1964, Li Pu et al., 1965) have attracted wide attention from the academic community. The main results of this expedition can be summarized as follows (Scientific Expedition of the Xixia Bangma Mountaineering Team in China, 1982):
(1) The geological framework of the Shisha Bangma area and its surroundings was clarified. The metamorphosed rocks on the area are classified as the Shisha Bangma herd and are dated to the Pre-Carboniferous (AnC). The lower group is located south of the 5800 m camp to Mount Everest, and the rock metamorphism is relatively high, mainly composed of gneiss, eyeball mixed rock and upper metagranulite, with more granite veins penetrating, while the upper group is located in the north of the 5800 m camp, the rock metamorphism is shallow, mainly schist, and the slab-like appearance is clear. The specific lithology includes amphibole quartz schist, mafic quartz schist, phyllite, metamorphic calcareous siltstone, etc., with marble appearing at the top and a small amount of granite veins penetrating. As will be explained later in this paper, the above two sets of rocks correspond to the present-day division of the High Himalayan crystalline rock series and the shallow metamorphic rock series of the Rouchecun Group/North Col, respectively.
(2) Stratigraphic systems since the Carboniferous have been established, including the Upper Paleozoic Gangmen Dome Group, the Mesozoic Tulong Group and the Shela Group, and the Cenozoic Yebokangale Group, but no Lower Paleozoic strata have been found. In particular, it is worth mentioning that the expedition team found the fossils of the Late Triassic giant ichthyosaur in the southern cycad mountain and the Nyalam Tulong area of Dingri (now Gangga Town), and named them Dingri Tibetan ichthyosaurs. Later discoveries in the Tulong area led to the name Himalayan ichthyosaurus (Dong Zhiming, 1973), which is the largest known marine reptile.
(3) Plant fossils were found in the lower conglomerate of the Yebo Kanggar Group in the 5800 m camp. The fossil was later identified by Mr. Xu Ren of the Institute of Botany, Chinese Academy of Sciences as Alpine oak, with a life age of about 3 Ma in the middle and late Pliocene, and the growth height should be about 2500 m, indicating that the place has been uplifted by about 3000 m since 3 Ma, which is the earliest and most accurate description of the uplift of the Qinghai-Tibet Plateau by Chinese scholars.
(4) A batch of isotopic age data was obtained. The age of 13~15 Ma was obtained by K-Ar dating of the eyeball gneiss and the granite-pegmatite intruded from the 5800 m area, while the age of the eyeball gneiss itself was 19~35 Ma. These ages, although surprisingly young, provide important information for the study of the genesis of the Shisha Bangma Peak.
(5) It is clear that the rocks at the summit of the Xisha Bangma Peak are metagranulites in the upper part of the lower Xixia Bangma Formation, and the previous understanding that the Xixia Bangma Peak is classified as a granite intrusion is wrong and should be corrected.
From the above induction, it can be seen that the scientific expedition of Xixia Bangma has gained a lot of valuable scientific understanding, especially the discovery and identification of alpine oak fossils (Xu et al., 1973), which has pioneered the research on the uplift of the Qinghai-Tibet Plateau in mainland geoscience. Encouraged by this expedition, mainland scholars soon discovered Miocene three-toed horse fossils in the Jilong Woma Basin (Huang Wanbo and Ji Hongxiang, 1979), which became another important discovery in the study of the uplift of the Tibetan Plateau in mainland China. More importantly, the Xisha Bangma expedition set the best precedent for the close integration of mountaineering and scientific research on the mainland. However, the expedition also left some regrets: first, the report completed after the climb was stifled by the "Cultural Revolution" before it was published, and the already arranged version was demolished (Sun Honglie, 1984). It was only in 1982, after the end of the Cultural Revolution, that the report was reformatted and printed, which seriously affected the dissemination of the academic results of the expedition. Second, the academic results of the Xixia Bangma expedition were mainly published in Chinese, so its influence in the international academic community was relatively limited. Even articles published in Science Bulletin in 1964 and 1965 were not disseminated in English. Due to the special era, in August 1964, at the international "Beijing Scientific Symposium" held in Beijing on the results of the Xisha Bangma expedition, foreign scholars from North America and Europe were not invited to participate (Zhang Jiuchen, 2007). The expedition report, published in 1982, also had only one page of English translations of the title and chapters. Even the article on alpine oak fossils published by Xu et al. (1973) has only half a page of English abstracts available for foreign scholars. If we search for literature published internationally, it is a pity that foreign scholars rarely cite the results of Shisha Bangma's investigation. In any case, the Xisha Bangma scientific expedition provided a successful example for the study of the Tibetan Plateau and the Himalayas on the mainland.
2 From Shisha Bangma to Everest
Mountains are the most familiar landscape to geologists. It can even be said that mountains are synonymous with geology. Therefore, the formation of mountain ranges is a fundamental task of geological research. The Himalayas are the highest mountain range on Earth, with 14 peaks above 8,000 m located in this mountain range, or the Himalaya-Karakoram Ranges more generally, which determines that the Himalayas are the natural laboratories for geologists around the world to study the formation and evolution of mountain ranges.
2.1 Everest expeditions by foreign scholars
Of the 14 peaks above 8000 m, 9 are located in the central Himalayas, of which 5 are related to China (Figure 1), from east to west, they are Makalu, Lhotse, Everest, Cho Oyu and Shisha Bangma. The first four of them are located on the China-Nepal border, and the latter are entirely on the mainland. Geological studies of these mountain ranges were earlier done by foreign scholars. In 1904, after the British invaded Tibet, they organized a number of expeditions to Mount Everest, including important geological expeditions: the first in 1921 and the third in 1924. Mallory and A. Irvine was killed on this expedition), the fourth in 1933 and the seventh in 1938, among others. In particular, it is worth mentioning that the term "yellow band" appears for the first time in Ruttledge's (1934) article. Allegedly, the term was applied during the first expedition in 1921. The yellow marble of this set of characteristics is not only an important symbol of Mount Everest mountaineering, but also an important marker layer for later geologists to divide the strata.
Fig.1 Geological map of the central Himalayas (a) and peak distribution map above 8000 m in the border area of China and Nepal (b)
(Photo from the Internet (1))
This phase of the Everest expedition is mainly carried out around the rocky composition of the summit. The first expedition in 1921 found that the rocks around Mount Everest can be divided into Tibetan sedimentary rocks and Himalayan crystalline rocks. The limestone and sandstone, with obvious east-west folding, show a north-to-south extrusion, while the latter is mainly composed of garnet biotite gneiss of varying degrees of surface in the lower part and calcareous gneiss in the upper part of the low-angle dipping north, with a large amount of tourmaline granite of intrusive origin (Heron, 1922), which is largely supported by later investigations (Odell, 1925). On a third expedition in 1924, Odell also collected limestone samples at an altitude of 8200 m, suggesting that the summit of Mount Everest may have been made of limestone (Odell, 1967). This assertion was also confirmed by the fourth expedition in 1933 (Ruttledge, 1934). During this expedition, L.R. Wager collected limestone samples at an altitude of 8,570 m (Wager, 1933b, 1934), referred to the rocks of Everest as the Everest Series, and further subdivided them into the upper Everest limestone and the lower Everest pelite, with the famous yellow band layer at the base of the Everest limestone. Based on the stratigraphic comparison with the southern slope of Mount Everest, this set of limestones at the summit of Mount Everest may be sedimentary of the Carboniferous-Permian. The lower part of the Everest pelite is slightly metamorphosed, during which there are more intrusive granite mats or, which are presumed to have been formed in the Early Paleozoic. In the fifties and sixties of the twentieth century, foreign scholars not only confirmed the existence of the summit limestone, but also found echinoderm fossil debris in the limestone, but its precise geological age has not yet been determined. Incidentally, on that expedition in 1933, Wager proposed the concept of Himalayan uplift based on the cutting characteristics of the river (Wager, 1933a).
In addition to these expeditions, the famous geologist Augusto Gansser conducted a long-term study of the Himalayas (Gansser, 1964) and proposed the following geological unit division scheme in the region (Figure 2):(1) Sub-Himalaya (Outer Himalaya), which is mainly composed of Siwalik conglomerate formed by weathering and denudation in the pre-Himalayas, which is a millstone formation of the foreland basin. It is adjacent to the Main Frontal Thrust (MFT) and Main Boundary Thrust (MBT) to the north and south respectively, and the Lower-Himalaya (also known as the Lesser Himalaya) to the north. This set of rocks is in contact with the Higher Himalaya (also known as the Greater Himalaya) in the north by the Main Central Thrust Fault (MCT), and (3) the High Himalaya: it is mainly a set of sedimentary rocks that have undergone amphibolite facies metamorphism, and there are a large number of eyeball granitic gneiss (granite intrusion about 500 million years ago). The metamorphism of this set of rocks gradually decreases from the bottom up, and then transitions to the Tethys or Tibetan-Himalayan (Tethys Himalayan or Tibetan Himalayas) in the upper part ;(4) Tethys Himalayas: mainly located on the northern slopes of the Himalayas, it belongs to the passive continental margin sediments on the northern margin of the Indian continent, and consists of Cambrian-Eocene unmetamorphic strata. In Nepal and Bhutan, on the southern slopes of the Himalayas, several of these rock-made overburdens are also found. In Gansser (1964), there is a gradual transition between the Tethys Himalayas and the High Himalayan in terms of metamorphism, suggesting an integrated sedimentary contact.
Fig.2 Tectonic profile of the Himalayan orogenic belt
（据Zhang et al., 2012修改）
2.2 Early work of domestic scholars
Chinese scientists' research on the Himalayas began after the founding of the People's Republic of China. In 1951, with the peaceful liberation of Tibet, the Central Commission of Culture and Education organized a Tibet task force headed by Li Pu, in which a geological group headed by Li Pu conducted a route investigation along the Sichuan-Tibet route (Li Pu, 1955; the geological group of the Tibet Working Group of the Chinese Academy of Sciences, 1959). Due to their first visit to Tibet, the expedition's expedition to the Himalayas was relatively limited.
In order to cooperate with the Chinese mountaineering team to climb Mount Everest, the Chinese Academy of Sciences organized a scientific expedition to Mount Everest in 1959, which was the first time that Chinese scholars conducted a comprehensive scientific research on Mount Everest. The geological group of the scientific expedition team is composed of 3 teachers including Liu Zhaochang of Beijing Institute of Geology (the college also sent 8 teachers and students including Wang Fuzhou to participate in the mountaineering team). They named the deep metamorphic rocks in the Himalayas as the Everest Complex, and subdivided them into the Longdui Group, the Kada Group and the Rongbu Group, whose age belonged to the Archean, and the shallower metamorphic tabular marble and mixed granitic gneiss in the area belonged to the Proterozoic, and considered that the relationship between them and the underlying Everest Complex was a micro-angle unconformity. Together, these two sets of rocks form the crystalline basement of the area, which is unconformably covered by Late Paleozoic-Mesozoic and Cenozoic sediments, and the Early Paleozoic strata are missing (Chinese Everest Mountaineering Team Scientific Expedition, 1962). Obviously, this expedition still maintains the understanding that foreign scholars believe that Mount Everest is composed of Late Permian limestone.
On May 25, 1960, three members of the Chinese mountaineering team, Wang Fuzhou, Gongpot and Qu Yinhua, climbed Mount Everest, which was a feat of human beings successfully climbing Mount Everest from the north slope. Unfortunately, due to time constraints, the mountaineering team did not leave any video footage to prove the successful ascent to the summit. In order to dispel foreign doubts about the mainland's successful ascent to the summit, the State Science and Technology Commission planned to climb Mount Everest for the second time around 1967. In order to cooperate with this mountaineering activity, the Chinese Academy of Sciences set up a Tibetan scientific expedition team headed by Liu Dongsheng and Shi Yafeng, and carried out field expeditions from 1966 to 1968. The geological group of the expedition team was headed by Chang Chengfa, and the scope of the investigation was from Yadong in the east to Jilong in the west, covering the range of Xixia Bangma Peak investigated in 1964, among which the investigation of Rongbu River Valley, Nyalam Ditch and Jilong Ditch was more detailed. However, due to the influence of the "Cultural Revolution", the summary of the results of this expedition was greatly affected, and the final results were published in 1974 (Tibetan Scientific Expedition of the Chinese Academy of Sciences, 1974). First, it was the first time that the Tibetan Plateau was divided into several plates, which were divided by multiple suture zones such as the Kunlun, Jinsha River, Nu River, and Yarlung Zangbo River (Chang Chengfa and Zheng Xilan, 1973), which was the first paper by a mainland scholar to explain China's geological evolution using plate tectonic theory. Since the author of the paper, Mr. Chang Chengfa, often mentions plate tectonics in the field, people give him the good name of "Chang Plate". Together with the "alpine oak" and "three-toed horse", the "Chang plate" has become a landmark achievement in the early research of the Qinghai-Tibet Plateau on the mainland. Second, the rocks in the Nyalam area were divided into three categories: the deeply metamorphosed Archean metamorphic rocks (Everest Group), the shallowly metamorphosed Cambrian-Ordovician (Meatchecun Group) and the unmetamorphosed Tethys Himalayan sedimentary rocks (Moon et al., 1973), and the Early Paleozoic strata (Ordovician Jiacun Group, later known as Jiacun Formation) were determined at the bottom of the unmetamorphic sedimentary rock series. This sequence was also applied to the northern slope of Mount Everest (Yin Jixiang, 1974), thus establishing a complete Phanerozoic stratigraphic sequence in the Himalayan region of Tibet on mainland China. Thirdly, the Rouchecun group can be further divided into the lower and upper groups according to the lithology, and there is an integrated contact between the two. The lower group is mainly diopside quartz schist interbedded with mica schist, interbedded with mixed rocks and mylonite, while the upper group is crystalline limestone. In addition to calcite, the lower group of rocks also contains minerals such as quartz, plagioclase, biotite, diopside, epidote, etc., among which calcite and quartz show obvious elongated deformation and are arranged in a directional manner. In other words, the lower group is dominated by argillaceous rocks with slightly stronger metamorphic deformation, while the upper group is dominated by calcareous components and the degree of metamorphic deformation is relatively weak. The investigation further pointed out that there is a reverse mask fault between the Rouchecun Group and the deeply metamorphosed Archean rock series, but there is an integrated contact with the overlying unmetamorphic strata (Chang Chengfa and Zheng Xilan, 1973). From the above introduction, it can be seen that one of the important achievements of the 1966-1968 expedition was that there was a fault between the High Himalayas and the Tethys Himalayas, and that there should be a tectonic contact between the two, rather than an integrated contact as previously believed, which has important academic value and promotion for the study of the Himalayas in China.
Regarding the composition of rocks at the summit of Mount Everest, this expedition still maintains the traditional understanding of the upper calcareous rock series (from 8300 m to the peak, about 300~500 m thick) and the lower argillaceous rock series (below 8300 m, with a thickness of more than 1200 m) (the yellow belt layer at the bottom of the calcareous rock series is the marker layer between the upper and lower sets of rocks). The lower argillaceous rocks are in contact with the deeply metamorphosed high Himalayan crystalline rocks through strongly deformed muscovite granite gneiss (i.e., pale granite mats), and the upper calcareous rocks can extend downward to the north to the area of Chaya Mountain, and the limestone in this area is basically the same as that of the Jiacun Group in Nyalam. Although no fossils have been found in the limestone in the Chaya area to prove its exact age, according to the regional comparison, the limestone at the summit of Mount Everest should have formed at the same time as the Jiacun Group limestone in the Nyalam area, that is, around the middle and late Ordovician. In 1960, when the Chinese mountaineering team reached the summit of Mount Everest, rock samples were collected at the summit and 8500 m, and they were all crystalline limestone. During the summary period of the laboratory, the isotope determination of these two rock samples was carried out, and the isotope age of U-Pb obtained was between 410~515 Ma, which verified the above speculation. It is worth pointing out that this expedition measured the stratigraphic profile of Chaya Mountain in the north of Mount Everest, and named the argillaceous rock series developed here as the Lower Formation of the Rouche Village Group, and found that there was a fault contact between the Rouche Village Group and the Jiacun Formation, but the significance of this fault and whether it was regionally representative were not further studied at that time.
In the 70s of the 20th century, the scientific investigation of the Qinghai-Tibet Plateau has received great attention at the national level. In 1973, the Chinese Academy of Sciences established a comprehensive scientific expedition team on the Qinghai-Tibet Plateau headed by Sun Honglie. This is the longest, largest, and most specialized scientific investigation since the founding of the People's Republic of China. The results of the investigation are reflected in dozens of published inspection reports. After the end of this expedition, the Chinese Academy of Sciences presided over a scientific symposium on the Qinghai-Tibet Plateau in Beijing in May 1980. Qian Sanqiang, then vice president of the Chinese Academy of Sciences, served as the chairman of the organizing committee of the conference, and Liu Dongsheng served as the secretary general. After the conference, more than 60 foreign scholars went on a two-week field trip to Tibet. This conference is the first large-scale international conference held in mainland China after the reform and opening up, and has been highly valued by Chinese and foreign academic circles. Deng Xiaoping met with some of the delegates at the meeting, and thus had a wide international influence.
As far as the Himalayan region is concerned, the biggest highlight of this expedition is that in order to cooperate with the Chinese mountaineering team to climb Mount Everest for the second time, the scientific expedition team set up a scientific expedition team of the Chinese mountaineering team headed by Zhang Hongbo. This is the third expedition to Mount Everest organized by the mainland, and it is also the most important expedition to Mount Everest. The expedition team is divided into three professional groups: geology, atmospheric physics and alpine physiology, of which the geological group participated in the field expedition Liu Bingguang, Zhang Hongbo, Wang Yipeng, Lin Chuanyong, Zheng Xilan, Yin Jixiang and other 6 people from the Institute of Geology of the Chinese Academy of Sciences, with Zhang Hongbo as the team leader. The results of his expedition were published in 1979 (1979 by the Tibetan Plateau Comprehensive Scientific Expedition of the Chinese Academy of Sciences and the Everest Scientific Expedition of the Chinese Mountaineering Team). During the 1975 climb of Mount Everest, the Chinese mountaineering team collected 65 rock samples at 45 different heights between 7029~8840 m, and the detailed results of these samples have been published (Yin Jixiang and Guo Shizeng, 1979). In 2022, during his field work in Tibet, the author met with three mountaineers, Luo Ze, Gongga Basang and Sangzhu, who had reached the summit and participated in the sample collection in Lhasa. They still have vivid memories of the sample collection that year. Gongga Basang recalled the process of collecting samples from the summit of Mount Everest, and said excitedly: "I fainted three times during the peak sampling, and I took three stones, but I didn't keep any of them. At that time, there is no second word about what place to give." At present, this set of samples is preserved in the Institute of Geology and Geophysics of the Chinese Academy of Sciences, and this is also the only set of relatively systematic rock samples of Mount Everest preserved in the world, which has important academic value.
During this expedition, Yin Jixiang and Guo Shizeng (1978, 1979) further divided the group of meat cut villages on the north slope of Mount Everest. During the 1966-1968 expedition, they found that the Rouche village group in the Chaya Hill area lacked the calcareous rocks of the Upper Formation. In this investigation, they named the argillaceous rock series of the lower group of the original Rouqicun Group as the Beiao Formation, and identified the calcareous rock series of the upper group from the upper part of the original Rouqicun Group, but gave this calcareous rock series a new lithostratigraphic unit name - Yellow Belt Layer. At the same time, the Jiacun Group previously determined here was named the Everest Formation (at the same time, the previously named Everest Group was abolished, and only the Rongbu Group was retained, which was used to denote the deep metamorphic rock series in the Everest area). In this way, the argillaceous rock series (lower formation) of the Rouchecun Group in the Nyalam area is equivalent to the North Col Formation in the Everest area, the calcareous rock series (upper formation) of the Rouche Village Group is equivalent to the Yellow Belt Layer, and the Jiacun Group is equivalent to the Everest Formation, and the rock strata of the two places can be completely compared.
As for the contact relationship between the North Col Formation and the Yellow Belt Layer and the overlying strata, more attention has been paid during this investigation. During the investigation of Chaya Mountain in 1966-1968, it was found that there was a faulty contact between the Rouche Village Group and the upper Jiacun Group, but it was difficult to determine whether it had regional significance, so Yin Jixiang and Guo Shizeng (1978, 1979) still insisted on the previous understanding, that is, the North Col Formation and the Yellow Belt Layer, and the Yellow Belt Formation and the Mount Everest Formation were all integrated contacts, but they were in fault contact with the underlying crystalline rocks (Rongbu Formation) as a whole. However, the measurement and study of more sections found that the North Col Formation and the Yellow Belt Layer, the Yellow Belt Formation and the Mount Everest Formation, and the Mount Everest Formation and the upper Carboniferous rocks were all fault contacts, which were named by Wang Yipeng and Zheng Xilan (1979) as the Lower Fault, the Fault Layer and the Upper Fault, respectively. The tectonic studies during the field investigation also showed that there were a large number of traces of fold deformation in the North Col Formation and the Yellow Belt Layer, and that the two sets of rocks as a whole could be treated as ductile deformed tectonic rock series, that is, "we feel that it is inappropriate to call this set of shallow metamorphic rock series sandwiched between the middle and lower fault zones, which are incomplete and have different outcropping thicknesses and strata, as "groups". At the same time, the report also pointed out that the Meat Cutting Village Group and the Jia Village Group in Nyalam Meat Cutting Village and Jia Village were also fault contacts, and were not integrated contacts as previously identified. The deformation of the yellow belt layer in the lower wall of the fault is obvious, and the limestone in the upper part has obvious fault breccia close to the fault. There is also a great difference in the degree of metamorphism between the two, and it is only because of the same occurrence on both sides and the cover of rocks that the two are mistakenly considered to be continuous sedimentation. In other words, the fault between the Yellow Belt and the Everest Formation is of regional significance. This understanding is a major breakthrough in Himalayan geological research. On this basis, Wang Yipeng and Zheng Xilan (1979) proposed the shingle-like structural characteristics of the north slope of Mount Everest, and Pan Yusheng (1980) further proposed that Mount Everest may be a thrust body from north to south. Despite the skepticism (Zhang Xinbao, 1981), this understanding was very much in line with the academic trend of the time in the seventies and eighties of the twentieth century, when the international definition of extensional structures in orogenic belts was still in its infancy (Davis and Coney, 1979, Crittenden et al., 1980). However, it is precisely because of the influence of this traditional academic thought, and because the research on ductile deformation was still in its infancy in China at that time, which led to problems in determining the direction of movement of these deformations.
Another important finding of the Everest expedition is the existence of a characteristic set of "muscovite gneiss" between the lower deeply metamorphic Rongbu Formation and the upper superficially metamorphosed North Col Formation. Although this set of rocks is strongly deformed, it can still be identified as a large mat of intrusive origin. In addition, there are a large number of mica granite, tourmaline granite, and tourmaline pegmatite intrusions in and below this set of gneiss, and occasionally a small number of biotite granite veins (Liu Bingguang and Zhang Hongbo, 1979). This set of rocks is what we now know as Himalayan pale granite. In fact, such granite intrusions have been repeatedly discovered by British expeditions during their ascent of Mount Everest (Heron, 1922, Wager, 1933a, 1934). Wager (1965) directly named it "injected granite sheets" in later research, and determined that its age was 14~16 Ma. At the same time, he also believed that these rocks were not the product of in-situ mixed lithification, but rather the horizontal intrusion of granite magma from deep crustal sources under differential stress conditions, which was supported by later studies (Searle, 1999b).
This expedition also collected abundant fossils of different phyla such as brachiopods and trilobites in Qianqiangou, Rongbusi Dongshan, Qiuharagou and other places in the north of Mount Everest, proving that the limestone at the summit of Mount Everest was indeed deposited in the Early Ordovician. Unfortunately, the limestone at the summit of Mount Everest has not made a breakthrough in the search for fossils. Later, Japanese scholars found trilobite fossils in the limestone of the peak (Sakai et al., 2005), which is a later story.
After entering the 80s of the 20th century, the Chinese Academy of Sciences moved the center of scientific research to the Hengduan Mountains in the eastern part of the Qinghai-Tibet Plateau and the northern and Karakoram regions further north and west, and the scientific research work in the Himalayan region came to an end temporarily. At this time, the door of China's reform and opening up had been opened, and the mainland has since organized and implemented a number of international cooperations, such as China and France, China and Britain, China and Germany, and China and the United States.
3 From domestic to international
In 1984, the Sino-French cooperation team proposed that the contact relationship between the Meat Che village group in the Nyalam area and the overlying Tethys Himalayan sediments should be normal faults (Burg and Chen, 1984, Burg et al., 1984). This view provides a new perspective for understanding the geological evolution of the Himalayas, and it suggests that the geological evolution of the Himalayas may have entered the extensional tectonic stage. In June of the same year, the Sino-French International Symposium on "Himalayan Geology" was held in Chengdu, and after the conference, a field trip to southern Tibet was organized. After the meeting, Clark Burchfiel from the Massachusetts Institute of Technology (MIT) proposed the idea of joint Himalayan geological research between China and the United States, which received a positive response from the Ministry of Geology and Mineral Resources at that time. Subsequently, MIT and the Chengdu Institute of Geology and Mineral Resources conducted in-depth cooperation on extensional structures in the Himalayas from 1986 to 1988, with the main participants of the American side such as Clark Burchfiel, Wiki Royden, and Kip Hodges, and the main Chinese researchers being Chen Zhiliang, Liu Yuping, Deng Changrong, Xu Jian'e, and Tang Wenqing. An important outcome of this expedition was the formulation of the concept of the South Tibetan Detachment System (STDS) (Burchfiel et al., 1992). During this period, the team also published the hypothesis that the Kangma Dome belongs to the metamorphic core complex (Chen et al., 1990). In particular, this collaboration not only found that extensional tectonics were prevalent in the Himalayas, but also that the age of MCT fault activity in the south of the Southern Tibetan Detachment was contemporaneous with STDS (Hodges et al., 1992). In this way, the predominantly extended upper crust and the predominantly compressive lower crust coexisted in the Himalayan region, which led to the later concept of Lower crustal flow in Royden et al. (1997).
IN 1994, A LARGE-SCALE, U.S.-China international cooperation focused on geophysical exploration began (indepth). This cooperation was fruitful, and Zhao Wenjin, the captain of the Chinese team, later systematically summarized it (Zhao Wenjin et al., 2008). In this collaborative study, the Main Himalayan Thrust was discovered, which led to the determination of the spatial geometry of the Himalayan orogenic belt (Fig. 2). Another important result was the discovery of a low-resistance feature in the deep crust of southern Tibet, which may suggest a molten state (Nelson et al., 1996). Encouraged by this discovery, the concept of channel flow has received sufficient attention (Beaumont et al., 2001). In December 2004, a symposium on crustal flows was held in London, which was followed by the publication of a collection of papers of the same name by the British Geological Society (Law et al., 2006). At this point, Himalayan research has entered a new stage.
The author spends such a long time introducing the process of Himalayan investigation and research, on the one hand, to show that scientific progress is always bit by bit, and it will always stand on the shoulders of predecessors, and there is no such thing as a mutation from "0 to 1". On the other hand, we congratulate Western scholars on their great academic achievements in Himalayan studies, but we also feel a little sorry for our predecessors. "Geology of the Himalays" (Gansser, 1964), published in 1964, was the most authoritative summary of the Himalayas in the world at that time. Gansser is also known as the "Father of the Himalayas". The book divides the Himalayan strata into three sets: the lower deep metamorphic series, the central shallow metamorphic series, and the upper unmetamorphic rock series, all of which are integrated sedimentary contact relationships (Fig. 3). In 1973, Chinese scholars named the above three sets of rocks as the Himalayan Group, the Rouchecun Group, and the Jiacun Group (above strata), and at the same time determined that there were faults between the deep metamorphic system and the overlying strata in the Nyalam area (Chang Chengfa and Zheng Xilan, 1973, Moon et al., 1973), which was the first important breakthrough in Himalayan geological research. However, when J.P. Burg proposed the Nyalam Normal Fault in 1984, he did not cite the Chinese research results at all. As for the rock composition of the summit of Mount Everest, Western scholars divide it into the lower argillaceous rock series and the upper calcareous rock system. Chinese scholars divide the upper calcareous rock series into the lower deformed Yellow Belt Layer and the upper Everest Formation limestone that has not undergone obvious metamorphic deformation, which is very different in history and nature, and the fault contact between the two is the second important progress in Himalayan geological research and the key breakthrough in the study of the rock composition of Mount Everest. In 1979, Chinese scholars not only determined that the limestone of the Everest Formation, which makes up the summit of Mount Everest, was in fault contact with the underlying strata, but also found that the shallow metamorphic rock series (Rouchecun Group) composed of the lower North Col Formation and the upper Yellow Belt Layer belonged to a set of ductile deformed rock series (Wang Yipeng and Zheng Xilan, 1979), and its tectonic significance was far greater than its stratigraphic significance, which was the third important progress in Himalayan research. On the basis of this understanding, Lombardo et al. (1993) and Carosi et al. (1998) defined the fault between the Lower Rongbu Formation and the Upper North Col Formation as the lower ductile extensional fault, and the fault between the North Col Formation and the Yellow Belt Formation as the upper low-angle normal fault. Searle (1999a), on the other hand, defines the lower fault between the Rongbu Formation and the North Col Formation as the Lhotse detachment fault, and the upper fault between the Yellow Belt Formation and the Everest limestone as the Qomolangma detachment fault, which is completely consistent with the lower fault and the fault layer proposed by Wang Yipeng and Zheng Xilan (1979), or the lower fault and upper fault proposed by Pan Yusheng (1980). As a result, Chinese scholars have made a number of key breakthroughs in Himalayan studies, but these achievements are rarely reflected in the literature of later Western scholars. Even in recent years (Kellett et al., 2019), there is no mention of the contributions of Chinese scholars. It is true that most of the above understandings of Chinese scholars are published in Chinese, but the author finds it hard to believe that during the international cooperation in the eighties and nineties of the twentieth century, Chinese colleagues did not introduce the work of their compatriots to Western scholars at all. Could it be that the differences in the direction of fault movement by Chinese scholars have led Western scholars to ignore the work of their Chinese counterparts?
Fig.3 Stratigraphic division scheme of the Himalayan orogenic belt
The author carefully sorted out the field expeditions of foreign scientists in the Himalayas around 1980. In October 1979, the U.S. "Plate Tectonic Delegation" visited China. This is the first foreign scientist to enter Tibet after China's reform and opening up. The delegation focused on the Yarlung Zangbo suture zone and the Red River fault. Although the delegation was aware of the stratigraphic sequence and tectonics studies established by Moon et al. (1973) and Chang Chengfa and Zheng Xilan (1973) in the Nyalam region (as both articles had been published in the English edition of Science in China) (Bally et al., 1980), they did not conduct any field research into the Himalayas in Tibet. After the 1980 Tibetan Plateau Scientific Symposium in Beijing, more than 60 foreign scientists went on a two-week field trip to Tibet (June 2-14). The geological field investigation was led by Liu Dongsheng, Yin Jixiang, Pan Yusheng, etc., and the investigation content included the stratigraphy, tectonic and metamorphic rocks of the Nyalam route (2). The expedition guide explicitly named the fault originally determined by Chang Chengfa and Zheng Xilan (1973) as the Chiatsun thrust fault, and arranged a special investigation time, which is clearly recorded in the later expedition summary (Shackleton, 1981). The author does not have a list of scientists who participated in the field expedition at that time, but Plumb's (1980) report shows that there were about 80 foreign guests (including relatives) on the expedition, which is consistent with the official data, indicating that a large number of foreign scientists participated in the field expedition in Nyalam. In July 1980, the three-year Sino-French cooperation project "Geological Structure of the Tibetan Himalayas and the Formation and Evolution of the Earth's Crust and Upper Mantle" was officially launched. Unlike Chang Chengfa and Zheng Xilan (1973), Burg et al. (1984) places the fault between the shallowly metamorphosed Meatche Village Group and the unspoiled Jiacun Group, but he does not give any account of the earlier work carried out by Chinese scholars in the literature. As we know, Chang Chengfa is (2) the vice captain of the Chinese side of Sino-French cooperation (the other deputy captain is Li Guangcen, and the team leader is Xiao Xuchang), who has participated in joint field trips and bilateral academic exchanges many times, and it is impossible not to introduce his research results in the Nyalam area to French scholars. We don't know if Clark Burchfiel, when he proposed Sino-American cooperation in 1984, had already had an idea or only came up with it after participating in the Himalayan field in June. As an internationally renowned geologist and one of the first to work on extensional tectonics in western North America, it was only natural that he had some new ideas about the Himalayas. But the author knows that Clark Burchfiel led the Sino-American cooperative research on the Haiyuan fault in 1982-1985 together with Academician Deng Qidong. Wang Yipeng was the main participant in the team, and had more contact with Clark Burchfiel, which is why the three faults identified by Wang Yipeng and Zheng Xilan (1979) were cited by Burchfiel and Royden (1985), but later the concept of STDS was summarized and proposed (Burchfiel et Al., 1992), Chang Chengfa and Zheng Xilan (1973) and Wang Yipeng and Zheng Xilan (1979) have largely ignored their work on fault tectonics.
Due to professional limitations, the author has not clearly figured out why the same set of metamorphic deformed rock systems was considered by early Chinese scholars to be thrust to the south, while later foreign scholars believed that it was to decline to the north. Decades have passed, and there are still few scholars who have a detailed interpretation of this issue. On the one hand, this reflects the complexity of the problem, but it may also be constrained by traditional ideas. Burchfiel and Royden (1985) have speculated that STDS may have thrusted southward in the early stages of evolution and collapsed northward due to the uplift of the Himalayas in the later period, but subsequent studies have not found much tectonic traces of thrust to the south (Burchfiel et al., 1992; al., 1993, Searle, 1999a), the current early southward thrust is largely based on conceptual extrusion orogeny. A similar situation has occurred in Nepal on the southern slopes of the Himalayas, where the fault between metamorphic and unmetamorphic rock formations was thought to thrust southward, and later it was suggested that it was mainly to the north. There are also scholars who put forward the idea of an early northward decline and a late southward thrust (Kellett et al., 2019 and its references). Obviously, this fault may not be so simple, and it may contain more mysteries waiting to be uncovered, because later studies have found that there is an east-west direction in the direction of movement of the fault (Xu et al., 2013). Fortunately, over the past 20 years, Chinese scholars are becoming the main force in Himalayan studies. We hope that Chinese scholars can make more and more original academic contributions to Himalayan studies. But we also hope that the important work of Chinese scientists will receive the attention of their Western counterparts.
In any case, decades of work by Chinese and foreign scientists have finally clarified the general rock composition and interrelationship of the Himalayas, that is, the lower part is the high Himalayan deep metamorphic rock series, the upper part is the unmetamorphic Tethys Himalayan sedimentary rock series, and the tectonic rock series that has undergone strong ductile deformation in between. Specific to the Everest area, the lower deep metamorphosed high Himalayan crystalline rocks can be named Rongbu Complex, while the bottom strata of the upper Tethys Himalayan sedimentary rock series are still recommended to be called the Everest Formation, so as to reflect the special geographical location of Mount Everest and its lithology is different from the Jiacun Group in the Nyalam area. Of particular importance is the nomenclature of the shallow metamorphic rock series between the two sets of rocks. This set of rocks in the Nyalam area was named the Rouche village group, but according to the nature of the rocks, it was suggested that it would be called the Rouche village complex in the future. In the Everest area, this set of rocks includes two stratigraphic units: the North Col Formation and the Yellow Belt Formation. Although their lithologies are different, they are the product of a unified evolutionary process of the Southern Tibetan Dissociation System, and it is recommended to refer to them collectively as the North Col Complex (Fig. 3). As for the age and nature of the original rocks of this complex, some scholars have classified it as a high Himalayan crystalline rock series, but they do not rule out the possibility that it was an early Tethys Himalayan sediment, that is, it may have been in unconformable contact with the High Himalayan in the early stage, and was later used by the Southern Tibetan Detachment System (Wang et al., 2024). However, in the eastern Himalayas (e.g., Loza), the stratigraphy of the Southern Tibetan Dissociative System is significantly higher and involves the Mesozoic strata (Burchfiel et al., 1992). Therefore, the tectonic significance of this set of rocks is much greater than its stratigraphic significance, and it is well worth a comprehensive regional study of this set of rocks in the future. In addition, studies in recent years have also found that a large number of light-colored granite outcrops in the Himalayas are also located along this fault, and crystallization differentiation and rare metal mineralization occur during the invasion process, which is also a new topic for future Himalayan research (Wu et al., 2021).
4 Return to Shisha Bangma
When geologists set their sights on Mount Everest, the Shisha Bangma was not as fortunate to be mentioned as often as Everest. After reaching the summit in 1964, the aura of Shisha Bangma faded to the point where it was almost forgotten. Even Chinese geologists no longer patronize this famous geological monument. Professor Peter Molnar, an internationally renowned scholar, wrote an article that clearly castignores the inferred time of the uplift of the Tibetan Plateau from the fossils of Quercus shisha Bangma (Molnar et al., 1993). In 1997, Professor Mike Searle of the University of Oxford, a renowned geologist and mountaineer, published the latest findings of the Hisha Bangma (Searle et al., 1997). He not only mapped the location of the southern Tibetan detachment system at Xisha Bangma, but also collected samples of the peak, which he believed was composed of granite. We do not know whether the author of the original article was aware that in 1964 Chinese scholars had proposed that the peak of Xixia Bangma was composed of metamorphic rocks (Liu Dongsheng and Shi Yafeng, 1964) rather than granite, as previously believed. Is there something wrong with that?
Out of curiosity, but also out of truth, I began to pay attention to the rocky nature of the summit of Shisha Bangma. From any point of view, the rock composition of a mountain above 8000 m located entirely in China should undoubtedly be answered authoritatively by Chinese scientists. The scientific research report of that year clearly pointed out that there were interbedded biotite gneiss and granite gneiss above 6900 m, granite gneiss and biotite gneiss bands at 7500 m, and no rocky outcrops at 7700 m. Samples were collected here by Wang Hongbao, a member of the mountaineering team, which is the highest altitude sample collected on this expedition, and its lithology is interbedded with granite gneiss and biotite gneiss (with quartz veins). However, Searle et al. (1997) reported in the literature that pale granite samples were taken at 7700 m, 7730 m, 7800 m and 8000 m. Due to the lack of detailed route descriptions, we cannot judge whether the route collected from the sample in the article by Searle et al. (1997) (1994) is the same as the 1964 Chinese mountaineering team's climbing route. However, judging from the photographs taken by mountaineers in recent years (Fig. 4), it is likely that the summit of Shisha Bangma is indeed characterized by a large number of pale granite formations, the so-called "injected complex". If this inference is true, it is likely that the dark traps in the pale granite at the summit of the Shisha Bangma peak are gneiss at the top of the High Himalayan crystalline series rather than the North Col complex. In any case, the rocky horizon at the summit of Shisha Bangma is much lower than that of Mount Everest, and its hidden geological significance is worth excavating.
Fig.4 Photograph of Shisha Bangma Peak
(a) Prospect of Xixia Bangma Peak (see Gangpeng Qingfeng on the right), photo from the Internet (3) ;(b) Granite and possible dark schist near the peak, photo from the Internet (4) ;(c) Xixia Bangma 5800 m base camp (on the left is the Cenozoic Yebokanggal Group strata, photo provided by Su Tao)
Obviously, finding the samples collected by the Chinese mountaineering team is a feasible way to sort out the above contradictions. The authors assumed that the samples should be kept at the Institute of Geology and Geophysics of the Chinese Academy of Sciences, but a search of all the records in the institute's museum found no clues. I also wondered whether these samples could be found in the Institute of Geochemistry of the Chinese Academy of Sciences, the Guangzhou Institute of Geochemistry of the Chinese Academy of Sciences, or even the Institute of Geographic Sciences and Natural Resources Research of the Chinese Academy of Sciences. The author spent nearly three years looking for samples at these research institutions, but basically found nothing. In April 2022, by chance, I learned that Dr. Su Tao, who was working at the Xishuangbanna Tropical Botanical Garden of the Chinese Academy of Sciences at the time, had seen the fossil of Alpine oak at the Beijing Museum of Natural History (now the National Museum of Natural History), and that he had returned to Xixia Bangma the year before and arrived at the 5800 m camp (Hu Minqi, 2021(5)). I immediately contacted Su Tao and learned that all the samples collected during the expedition were probably preserved at the Beijing Museum of Natural History. When I saw the rock samples that I had been looking for so hard, I was so excited. To my surprise, the samples were still labelled with the Institute of Geology, Chinese Academy of Sciences, but I really don't know how they got here, but luckily all the samples were well preserved!
However, careful examination revealed that the samples were taken from the base camp at 5800 m and below, and the rocks higher up to the summit were still nowhere to be found. I even doubt that the Chinese mountaineering team actually collected rock samples above the 5800 m camp. Examining Mr. Liu Dongsheng's field diary, there is this record on April 25, 1964: "Wang Hongbao of the second line carried more than 30 stones from the mountain, which seemed to be all semi-clay rocks, which were invaded by granitic materials. This coincides with a monoclinic structure seen at 5800 m". Mr. Liu Dongsheng also hand-painted a section of the rock composition of the summit of Shisha Bangma on the side of this text (exactly the same as the map he later published). Although the legend is not stated, it can be guessed that it is granitic gneiss in the lower part and metagranulite in the upper part. Therefore, there is no doubt that rock samples have been collected above 5800 m. Unfortunately, none of these samples have been officially reported in subsequent studies. If any of you know where these samples are kept, please contact the authors, as they are important for us to study the composition of the Shisha Bangma Peak. By the way, the Wang Hongbao mentioned here should actually be Wang Hongbao (sometimes referred to as Wang Hongbao). He studied at the Beijing Institute of Geology and worked in the Chinese mountaineering team after graduation. Most of the Everest rock samples currently preserved by the Institute of Geology and Earth were collected during his famous ascent to the summit in 1975. Sadly, he was killed in an avalanche on Mount Everest in October 1979. He was killed along with Nima Tashi, who had successfully climbed the peak of Shisha Bangma, and another member of the Chinese mountaineer, Laurent (Luo Lang).
Fast forward to 2024, which is the 60th anniversary of Shisha Bangma's successful ascension. The second Qinghai-Tibet expedition considered reaching the summit of Xifeng to collect ice, snow and rock samples. We are looking forward to it! Because the Chinese should have one or even several sets of rock samples from Xisha Bangma Peak. In this way, when we study the peak of Shisha Bangma again, we will no longer need to turn to foreign scholars. We can even provide them with samples that we have collected ourselves, as well as the results of research based on those samples. However, a mountain disaster in the fall of 2023 has put this plan on hold for the time being.
Despite this, in the past 60 years, geologists on the mainland have carried out a lot of fruitful work in the area around Shisha Bangma, and the Zhangmugou and Jilonggou on the east and west sides are currently the most studied Himalayan areas in the mainland. This album is a concentrated display of this work in recent years, and it contains a total of 19 articles, of which 13 are research work on Nyalam and Jilonggou centered on the Xisha Bangma Peak. The main achievements include: (1) the latest research progress on fossils such as three-toed horse and alpine oak in the Xixia Bangma peak area (Deng et al., 2024, Li Qiang et al., 2024, Liu Jia et al., 2024, Su Tao et al., 2024), ;(2) the basic rock composition of metamorphic rocks and granite in the Xixia Bangma Peak Mass, and their significance to the Himalayan orogeny and uplift process (Liu Xiaochi et al., 2024, Wang Jiamin et al., 2024) ;(3) the kinematic attributes of the southern Tibetan detachment system in the area around Xixia Bangma Peak, Activity age and development process (Chu Yang et al., 2024, Yan Jiaxin et al., 2024) ;(4) Pale granite and related rare metal mineralization in the surrounding area of Xixia Bangma Peak (Gao et al., 2024, Hou Kangshi et al., 2024, Hu et al., 2024, Xie et al., 2024, Yang Lei et al., 2024), etc. The above results fully show that the scientific connotation of Xisha Bangma Peak is constantly expanding, and the scientific investigation of Xisha Bangma Peak should continue.
5 Look again at the Himalayas
Uplift is a central theme in the study of the Himalayas and the Tibetan Plateau because it has affected our lives by altering the geomorphological and atmospheric circulation patterns of Asia (Molnar et al., 1993). But when the Himalayas and Tibetan Plateau were uplifted enough to affect Asia's climate is not an easy question to answer (An et al., 2001, Guo et al., 2008). The study of uplift is actually to elucidate the mechanism of uplift, and the solution of the mechanism depends to a large extent on the understanding of the uplift time and amplitude. It is generally believed that the collision between India and Asia led to the formation of the Himalayas and the Tibetan Plateau, which is a popular science statement that is far from the serious academic definition. At present, the academic community agrees that the Himalayas and the Tibetan Plateau may not be completely consistent in the history of uplift, and that differential uplift is the consensus (Wang et al., 2008). As far as the Himalayas are concerned, it is now generally clear that the collision between India and Asia began about 60~65 Ma ago, the Himalayan sea water withdrew around 40 Ma, and the Himalayan uplift occurred around 15~25 Ma (Ding et al., 2017, 2022). This understanding is far from what was realized during the 1964 expedition to Shisha Bangma, which is why the Shisha Bangma was revisited.
On the other hand, there is a great deal of controversy about the Himalayan uplift mechanism. The focus of this controversy is the formation mechanism of the Southern Tibetan Detachment System (STDS) (Zhang Jinjiang, 2007). It was earlier thought that STDS was a gravitational collapse due to the uplift of the Himalayas (Fig. 5a, Burg et al., 1984, Burchfiel and Royden, 1985, Burchfiel et al., 1992), but no evidence of significant uplift in the Himalayas prior to the development of STDS has been found. The tectonic wedge model is similar to that of a subduction tunnel (Fig. 5b), which explains the metamorphism of the High Himalayan to some extent, but the reason for the reentry of the rock series is not discussed. As a result, there is now a large number of scholars who support that it was the southward crustal flow that led to the uplift of the Himalayas (Figure 5c). This is a new orogeny mechanism that is completely different from the traditional theory of orogeny. The author's acceptance of the model has also taken a detour, but new facts continue to remind the author to strengthen the study of the model, only in this way can there be discovery and creation. The thrust stacking model is similar to the crustal flow model (Fig. 5d), which emphasizes that the high Himalayan rocks were located deep in the earth's crust earlier, but this is inconsistent with the metamorphic characteristics of high Himalayan rocks (Zhang et al., 2017, Wang et al., 2022). Therefore, we have repeatedly proposed (Wu et al., 2017, 2021) that the reentry of high Himalayan rocks may be due to the plate rotation of the subduction of the Indian mainland to the lower part of the Tibetan Plateau or related to the plate fragmentation. In this context, the deep thermal anomaly leads to a partial melting of the Indian continental crust at the subduction front, and then the partially molten crust moves upward along the early subduction interface due to density differences. The partially molten melt accumulates along the upper part of the detachment zone to form pale Himalayan granite in the form of mats, while the reverting Indian continental crust also undergoes a certain degree of partial melting due to decompression, forming deep melt veins in the high Himalayan series. Therefore, melt is a major factor in the reentry of rocks or the uplift of the Himalayas. Obviously, on a larger scale, a comprehensive study of the entire Himalayas is an important breakthrough that Chinese geologists may make in the theory of orogeny.
Fig.5 Pattern of Himalayan uplift and STDS formation
（据He et al.，2015；Kellett et al.，2019）
GHS and TSS stand for High Himalayan and Tethys Himalayas, respectively
The main reason why the Chinese reached the summit of Mount Everest in 1960 was the demarcation of the Sino-Nepalese border at that time. The Nepalese side believes that the Chinese have never summited Mount Everest and therefore have no right to decide where Mount Everest belongs. In the same year, almost all of the Earth's peaks above 8,000 m were conquered by humans, with the exception of the Xisha Bangma Peak in China. In desperation, the Chinese were forced to climb to the summit of Xixia Bangma Peak. Sixty years later, China's economy, science and technology and other aspects are no longer what they used to be, and professional mountaineering teams can no longer visit these peaks. Even amateur mountaineers, with the guidance of professionals, are not unattainable to reach the summit. In addition to the Everest and Shisha Bangma that we discussed earlier, do we know a lot about the other peaks above 8000 m in the Himalayas, especially Makalu, Lhotse and Cho Oyu on the border between China and Nepal?
Lhotse, the fourth highest peak in the world (8516 m), is another mountain on the southern side of Mount Everest on the border with China and Nepal. The north side of Mount Everest is separated from Zhangzi Peak by the north col, while the south side of the Everest is separated from Lhotse by the south col. According to Searle (1999a), the rocks of Lhotse are composed of shallow metamorphosed meat-cut villages, but the Chinese have never summited the peak from one side of their own territory. Even if we reached the summit from Nepal, we have not seen any samples collected from the summit and no reports of their studies. Fortunately, Lhotse is only 3 km away from Everest, and much of what we know about it can be borrowed from Everest. From the photographs taken (Fig. 6a), the rocks at the summit of Lhotse are horizontally located below the yellow belt layer and above pale granite. Therefore, Lhotse does consist of the North Col Complex. But another mountain on the border between China and Nepal, Makalu Peak, was not so lucky. Makalu Peak, the fifth highest peak in the world (8463 m), is located about 20 km southeast of Mount Everest. It is a well-known peak with pale granite peaks (Figure 6b) and is characterized by the occurrence of andalusite and iolite minerals. Western scholars have conducted more scientific studies on this issue, and found that pale granite exists in the form of mats with a thickness of 1~2 km (Schärer, 1984, Streule et al., 2010, Visonà et al., 2012). Unfortunately, the Chinese have never summited the peak from the side of the territory. Therefore, our understanding of the geology of this peak can only be based on the data of foreign scholars.
Fig.6 Photographs of several peaks and peaks in the Sino-Nepalese border region of the central Himalayas
(a) Mount Everest-Lhotse, (b) Makalu Peak, (c) Mount Everest, (d) Mt. Cho Oyu (photo from the Internet (6))
The author is a granite petrology worker and is very interested in the rock samples of Makalu Peak. However, foreign scholars have even mentioned (Searle et al., 2003) that there is a 7804 m peak on the north side of Makalu Peak, Mount Everest, which is completely located on the mainland, which is also composed of pale granite (Fig. 6c). Everest is the second highest peak in China after Shisha Bangma, followed by Nanga Bhava (7782 m), Namunani (7694 m), Gonger Peak (7649 m), Gongga Mountain (7556 m), etc. Everest and Everest echo each other, and together they have a beautiful name - Dolma. The French climbed it in 1954, and mountaineers from Japan, Russia, and the United States later visited the mountain, but the Chinese never climbed this mountain of their own.
Then to the world's sixth highest peak (8201 m) Cho Oyu Peak. It is located west of Mount Everest on the Sino-Nepalese border, separated by the world's 15th highest peak, Gyachung Kang (7952 m). The Chinese have summited the peak several times, but the studies we were able to retrieve on the peak were mainly published by Mike Searle. It was from the study of this mountain that he proposed the idea that the Himalayan pale granite was a large mat (Searle, 1999b). In 2008, the mountaineering team of China University of Geosciences climbed to the summit and collected 10 rock samples from 5793~6435m, which provides important information for us to understand the composition of Zhuo Oyou Peak and the geological evolution of the Himalayas (Gao et al., 2014, Yang et al., 2022). Unfortunately, almost no of these rock samples have been preserved. Moreover, at a height of about 1800 m in the upper part of the mountain, the mountaineering team did not take any samples. According to Searle (1999b), the summit of Cho Oyu is composed of the same Ordovician limestone as the summit of Mount Everest. From the many photographs taken so far (Fig. 6d), the 7700 m altitude of the Yellow Belt Layer of Cho Oyu Peak is clearly visible, and its lower part is a huge thick penetrating complex, and the limestone above the Yellow Belt Layer seems to be further divided into two types: the lower gray and the upper light, but we cannot give more information about the details of these rocks. In 2023, the second Qinghai-Tibet expedition carried out the summit of Zhuo Oyou Peak, and we were fortunate to obtain some rock samples from high altitudes. We hope that these samples will help us answer some of the key questions about the formation of this peak. But due to snow and ice cover, we still know very little about the rocky composition of the peak.
The author describes the rock composition of these famous peaks, which does not mean that geologists can only study the rocks at the summit, but hopes to promote the study of the overall geology of the region through the collection of peak samples. For the same reason, we also need to study the many peaks of the southern slopes of the Himalayas and related geological problems. The Himalayas are the youngest continental collision orogenic belts on Earth and are natural laboratories for the study of continental formation and evolution. But the Himalayas may still be inferior to the Alpine orogenic belts in terms of geology. From the founding of the People's Republic of China to the holding of the Qinghai-Tibet Plateau Scientific Symposium in 1980, Chinese scientists obtained research results represented by "Chang Plate", "Alpine Oak" and "Three-toed Horse" on the Qinghai-Tibet Plateau. Foreign scholars also did a lot of work in the vicinity of China at that time, gained a lot of important understanding, and even proposed a number of topics that would influence future research (Molnar and Tapponnier, 1975; However, at that stage, we lacked communication with the international academic community, which led to a certain degree of discomfort later. The last 20 years of the 20th century were the most active years in the study of Himalayan in the world. The proposal of the Southern Tibetan Detached System and the crustal flow model is not only to propose a new Himalayan orogenic or uplift model, but more importantly, to reveal the decoupling between different layers of the earth's crust, and to open up a comprehensive study of the deep and shallow and surface systems of the earth's crust (Molnar and England, 1990, Zhang et al., 2001). On the basis of the evolution of this academic idea, the Chinese Academy of Sciences established a comprehensive expedition team for the Mount Everest area headed by Kang Shichang in order to cooperate with the 2005 Mount Everest height measurement, and the leader of the geological team was researcher Ding Lin. This is also the fourth time that the mainland has conducted a comprehensive investigation and study of Mount Everest in an organized manner. Subsequently, the Chinese Academy of Sciences launched the project group "Paleoheight Research on the Qinghai-Tibet Plateau" (2009-2012) and the pilot special project B (2012-2016) on "Multi-layer Circle Interaction and Resource and Environmental Effects on the Qinghai-Tibet Plateau" with Yao Tandong and Wu Fuyuan as the chief scientists. Although the formation and evolution of the Himalayas is not the focus of these projects, the implementation of these projects provides an important basis for Chinese scientists to catch up with the pace of Himalayan orogeny research (Yao et al., 2015, Ding et al., 2017). In addition, the "Pan-Third Pole Environmental Change and the Construction of the Green Silk Road" (referred to as the Silk Road Environment) of the Chinese Academy of Sciences Pilot Special Project A and the "Second Comprehensive Scientific Expedition and Research on the Qinghai-Tibet Plateau" (referred to as the Second Scientific Expedition) are currently being implemented by Yao Tandong as the chief scientist, and the Himalayan geological research has ushered in a new turning point. The unique geographical location determines that Himalayan research must have a long-term plan at the national level to ensure that Chinese scientists can make a difference in Himalayan research and contribute to mankind.
This is not only the case with rock samples from famous mountains and rivers, but also in other aspects of research in the Himalayan region, which requires top-level design and long-term persistence. The altitude of Mount Everest is a highly popular issue, but it is also a very serious academic one. As geologists, we are concerned about whether the height of Mount Everest has changed. Or, how it has changed. If we count from 1975 to nearly 50 years ago, China has been measuring the altitude of Mount Everest with high precision (Table 1), but we cannot yet answer whether the mountain has grown taller or shorter in the past 50 years. The current data shows that the snow cover on Everest appears to have thickened, while the height of the rock face has decreased. However, these values are obtained in different years, using different methods, and using different reference systems, and whether they can be compared with each other needs to be interpreted by professionals. In other words, we need continuous observation to answer this question definitively, and this question is closely related to the formation of the Himalayas.
Table 1 Measurement of the altitude of Mount Everest
6 Conclusion
Shisha Bangma, Everest, Everest...... These famous mountains are now popular with many mountaineering enthusiasts, but geologists need to go to higher altitudes to investigate, collect samples, and study them. Climbing mountains above 8000 m is a challenge to the limits of human life, and it is even more difficult to obtain rock samples there (Zhao Yao, 2019(7)). But thanks to advances in technology, this kind of climb is no longer impossible for many non-professional climbers. So if any climber has made it to the summit, we congratulate you wholeheartedly, but if you can, take a sample of the rock and pass it on to a geologist you know or know. We need to answer the composition of these peaks, which is the responsibility of geologists. In today's increasingly self-employed or workshop-based scientific research, obtaining any rock sample from extremely high altitude peaks is an extreme luxury for geologists, but we can only do that.
Footnote:
(1) Photo URL: Autumn Life Check-in Season. Tibet's world-class avenue can encounter 9 8,000-meter peaks (2023-10-16, www.sohu.com/a/728652704_121119243).
② Organizing Committee, Symposium on Qinghai-Xizang (Tibet) Plateau. 1980. A scientific guidebook to south Xizang (Tibet). 1-104.
③ 照片网址：老蒙eki8d3tdc9. 阿里，阿里!（2）. 个人图书馆 (2021-8-14，www.360doc.com/content/21/0814/15/52773333_991028008.shtml).
(4) 照片网址: 飞雪静静 (BJ). 希夏邦马登山日记6-顶峰感受日出. Mafengwo (2008-11-2,https://www.mafengwo.cn/i/545628.html.
(5) Hu Minqi. Fifty years in the "forbidden area of life". China Science Daily, June 16, 2021, 4th edition.
⑥照片网址：(a) 珠穆朗玛峰与洛子峰. 摄图·新视界(https://xsj.699pic.com/tupian/0go3yv.html); (b)小A学长. 14座8000级高峰，你选哪个做座右铭? 新浪新闻中心 (2018-5-24，https://k.sina.com.cn/article_2077491865_7bd402990010061on.html); (c)珠峰东坡· 嘎玛沟·世界十大经典徒步线路·12日之旅. 山人行旅行(www.sc3rx.com/detail.html?iid=3139&activityId=20034844); (d) https://(刘小驰提供)及https://bbs.8264.com/thread-5522187-1-1.html(插图).
(7) Zhao Yao. Have you ever seen what the stones look like on 14 peaks over 8,000 meters above sea level?ChinaTibet.com (2019-3-10, media.tibet.cn/wap/photo/content_11845.shtml).
About the Author:
Fuyuan Wu (State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences; School of Earth and Planetary Sciences, University of Chinese Academy of Sciences): Researcher, engaged in petrology research.
Foundation Item:
*This work was co-funded by the National Natural Science Foundation of China (91755000) and the Second Tibetan Plateau Comprehensive Scientific Expedition (2019QZKK0808).
This study was published in Acta Petrologica Sinica, Vol. 40, No. 5, 2024:
Wu Fuyuan. 2024. Sixty Years of Hisha Bangma Peak. Acta Petrologica Sinica, 40(5): 1365-1381.
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