The Qiangtang Basin is the biggest petroleum-bearing basin in the Qinghai-Tibet Plateau. This basin experienced a foreland basin evolution during the Early- Middle Triassic and a rift basin evolution during the Late Triassic-Early Cretaceous. Triassic and Jurassic hydrocarbon source rocks were widely distributed throughout the basin. The Triassic Tumen Gela Formation coal-bearing mudstones represent the best source rocks because of high total organic carbon (TOC) content (1.25-3.45%) and HI values (2.8-123 mg/g Toc), and the Xiali Formation mudstones are moderately-good source rocks with an average TOC content ranging from 0.55 to 7.30% and HI values ranging from 7.0 to 165 mg/g Toc. The Jurassic Buqu Formation and Suowa Formation carbonates, however, exhibit poor-to fair-quality as hydrocarbon source rocks. Excellent dolomite and paleokarst reservoirs and mudstones and bearing-evaporite marl cap rocks, together with well-developed structural traps are recognized in the basin. Additionally, a large paleo-oil-reservoir zone has also been discovered.Based on an integrated petroleum systems analysis, nine favorable hydrocarbon exploration areas are proposed, of which the Tuonamu area and Badaohu area are selected as the potential targets for the exploration for oil and gas resources in the basin. Good reservoir quality dolomites in the Buqu Formation are considered to have a significant exploration potential. (C) 2016 Elsevier Ltd. All rights reserved.

This paper analyzes the time differences between stations using least square method based on three-way tracking measurements of Chang'E 3probe,and achieves nanosecond level fitting accuracy on 5degree fitting.The precise ephemeris of the probe is used to calibrate the three-way measurements.Following the correction,the error of the ranging system decreases to 10 mlevel and the fitting noise level is improved to better than 1 m.Finally,three-way measurements are used in orbit determination,lunar landing positioning and powered descent trajectory calculation for the probe.As a result,the bias of the 100 km × 15 km lunar orbit compared to the precise orbit is100 mlevel,the bias of the 120 km ×70km lunar orbit is 10 mlevel compared to the precise orbit,and the bias of lunar position compared to the position calculated by two-way ranging and VLBI(Very Long Baseline Interferometry)delay is 10 mlevel.

主要讨论了动量轮卸载对嫦娥一号卫星绕月轨道的影响以及这种影响对其精密星历衔接段精度的影响,分析了不同轨道改进策略下的精密星历衔接弧段的精度,认为使用2～3d的弧段进行轨道改进及卸载计算能得到较高精度的搭接星历,并通过使用实测数据进行定轨改进计算进行了验证,结果表明,该策略可以使星历衔接精度在沿迹方向(T)提高至优于100m量级.

针对我国探月工程再入返回段分离前的精度要求,在无法实现对再入返回器的三向测量情况下,提出多站接力跟踪的测量策略,以解决测定轨精度不高的问题.结合再入返回分离前的测控弧段,制定两站及三站接力跟踪的策略.利用ESA"桑巴"(SAMBA)卫星进行多站接力跟踪试验数据分析,结果表明,三站接力跟踪策略的定轨预报精度优于两站接力跟踪策略,能够实现返回器安全可靠地再入返回,可为再入返回任务分离前跟踪策略的制定提供依据.

The Qiangtang Basin is a significant prospective area for hydrocarbon and gas hydrate resources in the Tibetan Plateau, China. However, relatively little work has been performed to characterise heat flow in this basin, which has restricted petroleum and gas hydrate exploration. In this study, we compare present and palaeo-heat flow in the Qiangtang Basin to provide information on geothermal regime, hydrocarbon generation and permafrost that is necessary for further petroleum and gas hydrate exploration. We base our study on temperature data from a thermometer well, thermal conductivity tests, vitrinite reflectance data, homogenisation temperature data from fluid inclusions, stratigraphic information and a time-independent modelling approach. Our results indicate that in the central Qiangtang Basin, the present thermal gradient is approximately 15.5 degrees C/km, and heat flow is approximately 46.69 mW/m(2). Heat flow in the Qiangtang Basin is not relatively stable since the Early Jurassic, as previous research has suggested, and it is generally decreasing with time. Additionally, there is a clear difference between the hottest thermal regime of the southern and northern Qiangtang Depressions during Cretaceous to Pleistocene time. In the southern Qiangtang Depression, the palaeogeothermal gradient is approximately 32.0 degrees C/km, and palaeo-heat flow is approximately 70 mW/m(2). However, in the northern Qiangtang Depression, the palaeogeothermal gradient exceeds 81.8 degrees C/km, and palaeo-heat flow is greater than 172.09 mW/m(2). The high thermal regime in the northern Qiangtang Depression is driven mainly by hydrothermal convection. Gas reservoirs are possible targets for hydrocarbon exploration in this depression. Currently, the northwestern part of the northern Qiangtang Depression is the most favourable area for gas hydrate exploration in the Qiangtang Basin. (C) 2014 Elsevier Ltd. All rights reserved.

The Qiangtang terrane is located in the central part of the Tibetan Plateau, where the Mesozoic geological evolution has great significance for revealing the closure of Paleotethyan ocean and the disintegration of Gondwanaland. In order to find out the Mesozoic evolution of the Qiangtang terrane, more than 200 paleomagnetic samples were collected from the Upper Trassic Tumengela Formation and Zala Formation both in the north and in the south Qiangtang. Most samples contained two components of magnetization in thermal demagnetization experiments. The most stable high-unblocking temperature components were isolated and passed positive reversal tests at the 95% confidence level, which suggested that these high-temperature components could be regarded as primary characteristic remanent magnetization. The mean characteristic magnetization directions of the samples from north Qiangtang and south Qiangtang were D/I=28°/45.5° (a 95=3.6°) and D/I=35.3°/46.5° (a 95=4.0°), respectively. Nearly similar paleomagnetic polar and palaeolatitude, obtained from the north Qiangtang and the south Qiangtang, indicated that they had already belonged to one plate in the Late Triassic. The Late Triassic paleolatitude of Qiantang terrane was 27° in the Northern Hemisphere. Combined with previously reported paleomagnetic results, the paleomagnetic polar wandering paths were obtained. According to the paleomagnetic polar wandering paths, the Qiangtang terrane was located in the Southern Hemisphere during the Late Paleozoic and very close to the Equator in Late Permian. It drifted fast northward from the northeast Gondwanaland from the Late Paleozoic to the Mesozoic. The Qiangtang-Tarim plate collision finished at the end of the Triassic, and the Qiangtang-Lhasa collision might finish in the Middle Cretaceous. By then, all suture movements between Qiangtang terrane and other blocks had finished.

The newly-discovered paleoweathering crust sediments are developed beneath the continental volcanic rocks,sedimentary-volcaniclastic rocks,and alluvial-diluvial sandstones and conglomerates from the Upper Triassic Nadigangri Formation,and diachronously overlapped upon the Upper Triassic(?)Xiaochaka Formation and its underlying strata including the Carboniferous-Permian strata in the Qiangtang Basin,indicating a sedimentary gap between the Nadigangri Formation and its underlying strata.These volcanic rocks,sedimentary-volcaniclastic rocks and alluvial-diluvial sandstones and conglomerates from the Nadigangri Formation deposited above the paleoweathering crust represent the onset of the Qiangtang Basin sediments during the Mesozoic.The SHRIMP zircon U-Pb isotopic dating gives the ages of 219.5±2.1 Ma and 219±2 Ma for the basalt and granodiorite from central Qiangtang,and 216.8±2.1 Ma and 217.3±2.5 Ma for the vitric tuff and crystal tuff from the Nadigangri Formation in the Shenglihe and Wanghuling areas in the Qiangtang Basin.All these age determinations imply that the onset of the Mesozoic Qiangtang Basin should be traced back to the Late Triassic.The deposition went through the continental to marine sedimentary overlap during the early evolution of the Mesozoic Qiangtang Basin.The sedimentary overlap started from the alluvial-diluvial facies and accompanied by magma intrusion,volcanic eruption and pyroclastic deposition.On the whole,the deposition displays a deepening-upward transgressive sequence,characteristic of a passive marginal rift basin.

Most information about the source rocks in Qiangtang basin are originally taken from analytical data of the outcrops. This paper presents correlation and analysis of the characteristics of the source rocks in Qiangzi-2 well and on the surface in Zharen area in southern Qiangtang depression. And some differences of source rocks between them are revealed in lithology,organic matter's abundance,type and maturity,etc. The result shows that the content of organic carbon of Qiangzi-2 well is higher than that on the surface condition,and the type of organic matter is dominated by Type Ⅱ1 kerogen,very little with TypeⅡ2 kerogen,and also the evolution degree of organic matter is obviously low. It is concluded that the source rocks in Qiangtang basin is of very good potential of hydrocarbon generation. This is significant to the proper evaluation of the source rocks in Qiangtang basin.

The Late Triassic Nadi Kangri volcanic rocks, with nearly EW trending outcrops within the Qiangtang basin, northern Xizang (Tibet), China, are composed mainly of acid tuff, dacite, rhyolite and minor basic volcanic rocks. There exists a significant depositional hiatus between the Nadi Kangri volcanic rocks and underlying strata. Therefore, the Nadi Kangri volcanic rocks represent a new evolution history of the Mesozoic Qiangtang basin. The magma emplacement age of the Nadi Kangri volcanic rocks in the Geladaindong area is 220.4 +/- 2.3 Ma, representing the onset of the Mesozoic Qiangtang basin. The Nadi Kangri basalts have high Nb/Zr (0.049-0.058), Ta/Hf (0.12-0.15) and Zr/Y (4.95-6.01) ratios. In the tectonic discrimination diagrams, such as Zr vs. Zr/Y and Th/Hf vs. Ta/Hf, the Nadi Kangri basaltic rocks mostly plot in the "within-plate" setting field. The geological background and the geochemical characteristics suggest that the Nadi Kangri volcanic rocks were formed in a continental rift setting. Crown Copyright (C) 2009 Published by Elsevier B.V. on behalf of International Association for Gondwana Research. All rights reserved.

A suite of sedimentary-volcaniclastic rocks intercalated with the volcanic rocks unconformably overlies the Triassic Xiaochaka Formation in the Woruo Mountain region, Qiangtang Basin, northern Tibet. The vitric tuff from the base of these strata gives a SHRIMP zircon U-Pb age of 216 ± 4.5 Ma, which represents the age of the Late Triassic volcanic-sedimentary events in the Woruo Mountain region, and is consistent with that of the formation of the volcanic rocks from the Nadi Kangri Formation in the Nadigangri-Shishui River zone. There is a striking similarity in geochemical signatures of the volcanic rocks from the Woruo Mountain region and its adjacent Nadigangri-Shishui River zone, indicating that all the volcanic rocks from the Qiangtang region might have the same magmatic source and similar tectonic setting during the Late Triassic. The proper recognition of the Late Triassic large-scale volcanic eruption and volcanic-sedimentary events has important implications for the interpretation of the Late Triassic biotic extinction, climatic changes and regressive events in the eastern Tethyan domain, as well as the understanding of the initiation and nature, and sedimentary features of the Qiangtang Basin during the Late Triassic-Jurassic.

藏北羌塘沃若山地区三叠系肖茶卡组之上不整合沉积超覆了一套沉火山碎屑岩夹火山岩地层,该套地层底部的玻屑凝灰岩夹层的SHRIMP锆石U-Pb年龄为（216.1±4.5）Ma,该年龄代表了沃若山地区晚三叠世火山-沉积事件的时代,它与最近获得的羌塘盆地广泛分布的那底岗日、石水河等地区的那底岗日组火山岩的形成时代基本一致,同属晚三叠世.微量元素及同位素地球化学特征表明,沃若山地区火山岩的地球化学特征与其相邻的那底岗日、石水河等地区的那底岗日组火山岩十分相似,表明该时期羌塘地区的火山岩可能具有相同的岩浆源区和相似的构造环境.羌塘盆地晚三叠世大规模火山喷发与火山-沉积事件的正确认识,对于探讨东特提斯域晚三叠世生物绝灭、气候变化与海退事件具有重要的意义,同时,对于了解晚三叠世-侏罗纪北羌塘地区新一轮盆地演化的开启时间、盆地性质及沉积特征也具有重要的意义.

Up to now, no gneiss has been reported in the Qiangtang basin. Divergent views have long existed as to whether the pre-Paleozoic crystalline basement occurs in the basin. Recently gneiss with the medium- and high-grade metamorphic features has been found in the vicinity of Ejiumai near Lanxin Mountain on the northern margin the Central uplift zone in the Qiangtang basin. Through tracing, the authors found a gneiss outcrop, which is 50-200 m wide and 4 km long, extending discontinuously along a thrust. Petrographic study shows that the gneiss contains the typical regional metamorphic minerals sillimanite and kyanite, and in addition, it has been found that the nearby Ordovician only undergone low-grade metamorphism and recent geophysical data have revealed that there might be crystalline basement in the Qiangtang basin. Based on these findings, the authors preliminarily conclude that the Ejiumai gneiss is a slice of pre-Ordovician crystalline basement in the Qiangtang basin and that a stable crystalline basement might occur at the depth of the Qiangtang basin.

The Nadi Kangri Formation in the North Qiangtang basin, northern Tibet, is a suite of continental volcanic rocks with volcaniclastic and terrigenous clastic rocks, which unconformably overlies the Triassic Xiaochaka Formation limestone and disconformably underlies the Jurassic Qoimaco Formation terrigenous clastic rocks. According to the existing data, its age is assigned to Early Jurassic. SHRIMP U-Pb zircon ages of two Nadi Kangri Formation rhyolitic crystal tuff samples and one Nadi Kangri Formation rhyolitic dacite sample collected from different areas of the North Qiangtang basin are 205±4,208±4 and 210±4 Ma respectively, which represent the formation ages of the Nadi Kangri volcanic rocks, i.e. the age of the Nadi Kangri Formation should middle Late Triassic (Norian Stage) rather than Early Jurassic. The redefinition for the ages of the Nadi Kangri volcanic rocks is of great importance to the understanding of Mesozoic volcanic events and basin type and sedimentary-tectonic evolution of the Qiangtang basin in northern Tibet.

Because of the chaotic stratigraphic division of the Mid-Lower Jurassic dark-colored rock series in the Doima stratigraphic area, southern Qiangtang, the authors measured the Songke′er section in Sewa during the petroleum geological survey in 2005 and systematically collected abundant ammonoid fossils with chronological significance. Based on the identification of ammonoid fossils, combined with the sedimentary filling sequence, sedimentary facies and sequence stratigraphy, the dark-colored rock series is redefined. The black and dark gray mudstone-shale with limestone in the middle and lower parts of the section and dark gray limestone and marlstone with mudstone are defined as the Lower Jurassic Quse Formation, while gray and dark gray silty mudstone-shale in the upper part of section is defined as the Middle Jurassic Sewa Formation. The collection of abundant ammonoid fossils and redefinition of the strata in the section not only enrich the content of paleontology in the area, but also have great scientific significance for the stratigraphic division and correlation of the Jurassic and study of the paleogeographic evolution in the study area.

Grape and snowflake shaped dolostone was generated from the leaching action after the formation of original dolostone.Organic material in the ″grape″ or around ″snowflake″ is not original alga but bacteria assemblage which come from decayed blue green alga.The formation of the dolostone is closely related to sedimentary environment.Grape and snowflake shaped dolostone is not only an oil producing formation,but also a prosperous oil reservoir rock and therefore,provides new way of oil and gas exploration.

The Ordovician limestone of the Baota Formation is widespread in the Yangtze carbonate sedimentary area. It is characterized by the irregular, cockscomb-shaped decorative pattern on the surface of the bedding, and is usually called chapping grain limestone. Three factors are responsible for the formation of this special decorative grain fabrics. The first is the sedimentary-tectonic background of the basin. The uplift of the foreland basin resulted in the inclination of carbonate platform, forming a deep water basin on the craton in the Ordovician and providing a low energy, low velocity environment for the sedimentation of mud-limestone and lime-mudstone. The second one is the ecology and biogliph of the deep water environment. Swimming Orthocerida and huge Molluses left marks on or in the soft mud and lime. The last one is the diagenesis of limestone and mud, which superimposed on the imprint. Therefore, the formation of Baota limestone is the combination of sedimento-tectonic, ecological and diagenetic facies.