General situation of natural economic geography and working conditions

1:250,000 The investigation area of Chaka District in Magel is located in the Hoh Xil area in the north of Qiangtang Plateau, and the administrative division belongs to Shenzha County in Xizang Autonomous Region (most of the investigation area) and Qiemo County in Xinjiang Uygur Autonomous Region (a small part of the northwest corner). Geographical coordinates: 85 30' ~ 87 00' east longitude, 35 00' ~ 36 00' north latitude, and the international framing code is I45C00 1002 (figure 1- 1).

Figure 1- 1 traffic location map

The investigation area is located in the northern Qiangtang Plateau and the western section of the Hoh Xil Mountains. The Hoh Xil Mountains extend from east to west in the northern part of the survey area. In addition, there are Samari Gari Mountain in the middle, Suijia Mountain, Shizhapo Mountain and Shengli Hunan Mountain in the south. Generally, all mountain systems extend from east to west, and the mountainous terrain is strongly cut. Glaciers are distributed along the main peak of the Hoh Xil Mountains, and there are many rivers in the mountains. Between or on both sides of mountains and mountain systems, there are mountain depressions extending linearly from east to west, modern alpine lakes are developed, and swamps are everywhere. Generally speaking, the landform pattern of alternating distribution of plateau mountains and plateau intermountain basins has been formed. The altitude of this area is generally 4900 ~ 5200 meters, with the highest peak of 6325 meters. The altitude of plateau lakes in intermountain basins is the lowest, generally around 4800 meters.

The river network in the investigation area is developed, all of which belong to inland rivers, and most of them belong to a single closed centripetal water system centered on lakes. The water flow is mainly supplied by seasonal ice and snow melting, and it is mostly undercurrent in winter. The main rivers in the area are Muddy Water River (about 120km long), Wolong Shahe River (about 100km long) and Shengjing River (about 55km long). Most of these rivers originate from glaciers and eventually flow to mountainous depressions to form lakes. Glaciers in this area are developed in the Qiangzhiling and Yunwuling areas in the northwest of the investigation area. The main lakes are Yongbo Lake, Zhenquan Lake, Shengli Lake, Margai Chaka Lake and Dragon Boat Lake. Among them, Margai tea card is the largest, with an area of about 100 km2, and the water quality of all lakes is generally slightly salty.

Due to the extremely high terrain, the climate of the work area is divided into the sub-cold zone arid climate zone of Qiangtang Plateau, which is a typical continental climate with the characteristics of dryness, cold, low pressure, strong wind, long sunshine time and severe hypoxia. According to the meteorological data collected in the south of the investigation area (about 300 km south of the investigation area), the annual average temperature is below 0℃, and the minimum temperature is -33. 8℃, the hottest is July, and the average temperature is 12℃. The average monthly pressure is 596. 3 millibar (equivalent to 0. 588 standard atmospheric pressure), the minimum pressure is 589 mbar (equivalent to 0. 58 1 standard atmospheric pressure). Annual precipitation 127 mm, and June-July accounts for about 93% of the annual precipitation. The temperature difference between day and night is large, even in summer, there will be snowfall, and the weather is changeable. Sometimes it's clear in Wan Li, sometimes it's covered with dark clouds, and it's windy and snowy, and thunder rumbles.

The investigation area is located in the national first-class nature reserve, Qiangtang Hoh Xil Nature Reserve in northern Tibet. There are sparse plateau vegetation development, mainly Stipa purpurea and Bryophyta sclerophylla, and there are cushion Ceratoides flora; Wild animal resources are abundant, mainly including Tibetan antelope, wild yak, Tibetan wild donkey, argali, brown bear and so on.

The investigation area is a famous cold no man's land, which is often called "life forbidden zone" and "mysterious death zone". The main reasons are cold and lack of oxygen, bad climate, difficult passage, scarce vegetation and no minimum material basis and living conditions for human survival and reproduction. It's hard for people who haven't been to this area to imagine the difficulty of carrying out geological survey in the no-man's land in northern Tibet, but1∶ 250,000 Magechaka geological survey area is located in the hinterland of no-man's land in northern Tibet, far from traffic arteries, and it's not easy to reach this area, not to mention the "danger and hardship" of carrying out regional geological survey here is unimaginable to ordinary people.

Extreme working conditions mainly come from the following aspects:

1. The investigation area is located in the hinterland of no man's land in northern Tibet Plateau, with a linear distance of 400 ~600 km from the main traffic arteries such as Qinghai-Tibet Highway, Xinzang Highway, Highway in the middle of Qinghai-Tibet Plateau and Highway in the southern margin of Tarim Basin. Only seasonal mountain service roads reach the work area, and they need to cross mountains, rivers, alpine lakes and swamps on the way, which makes it very difficult to supply living and production materials. There are three material supply places close to the three joint investigation areas, namely Qiemo County in Xinjiang, Huatugou Town in Qinghai and Golmud City. Qiemo County is about 800 kilometers west of the three joint investigation areas, and Huatugou Town and Golmud City are about 800 kilometers and 640 kilometers east of the three joint investigation areas respectively. To supply materials from the above areas, it is necessary to cross the vast no-man's land in northern Tibet, with countless mountains, lakes and swamps on the way. We chose Qiemo County in Xinjiang to provide supplies when we completed the task of Magai Chaka investigation area. On the way, you need to cross Kunlun Mountain, Kumubuyan Mountain and other high mountains, but there are few swamps on the way, which is suitable for hiking in June-August when the plateau frozen soil is thawed.

Secondly, the survey area is generally about 5 000 m above sea level, belonging to a cold and oxygen-deficient area. The oxygen content in the air is only 45% ~ 55% of that in coastal areas. The air is very thin, and the average annual temperature is below 0℃. It will snow even in the hottest July. Thin air and cold temperature bring challenges to people's survival. In order to overcome the cold and lack of oxygen, we are equipped with winter clothes, heating stoves, oxygen, anti-altitude sickness drugs and altitude doctors.

Thirdly, the survey area is no man's land, with mountains, rivers, plateau lakes and swamps. There is no ready-made traffic road in this area, and the traffic conditions for geological survey in the survey area are extremely bad. Because of traffic jams, bad ice and snow weather and so on, the journey within 100 km often takes three or four days. Every time I think of the scene of struggling in the snow on the road, people are now.

In order to overcome the difficulties of geological survey in the survey area, according to our experience, the following working conditions must be met. First of all, we should have good working equipment, including vehicles, communication equipment, living materials and so on. Second, the medical and health conditions necessary to deal with mountain reaction; Third, select young geologists who are healthy and can adapt to mountain operations to form a project team.