Abstract:On the basis of new collections from the Lanongla area, Nyalam county, Tibet, Rhaetian and Hettangian ammonoid assemblages are recognized, including the Choristoceras marshi, Neophyllites-Charistoceras, Psiloceras calliphyllum and Discamphiceras pleuronotum assemblages. As the only Triassic and Jurassic boundary section known in the East Tethys, the Germig section provides a biochronological correlation in term of ammonoid assemblage, or zonation in the Tethyan domain; the Choristoceras marshi assemblage is comparable with the MARSHI, or CRICKMAYI Zones of Europe, Peru and Chile, Nevada, British Columbia. Neophyllites and Chorstoceras co-occur in a transitional interval between the Choristoceras marshi and Psiloceras calliphyllum assemblages, which can be likely comparable with that in Nevada of North America where both Neophyllites and Choristoceras appear in the basal Jurassic TILMANNI Zone. The Psiloceras calliphyllum assemblage is most likely equivalent to the CALLIPHYLLUM Zone of North Alps and the PLANORBIS Subzone of Northwest European Province.

Abstract:In a bedded chert section at Dachongling in Xiaodong town of Qingzhou, Guangxi, the authors found a rare earth elements (REE) geochemical anomaly zone with higher Ce/Ce* values, a positive Ce anomaly zone (the background is negative Ce anomalous zone) in the shale-normalized REE pattern, and a zone of sharp lithological change at the basal boundary of the Lopingian Series. These zones coincide with the zone of sharp change in radiolarian groups. This fact may indicate that the pre-Lopingian crisis event are reflected very well in this section. It is inferred that the cause of the event was a global regression at the end of the Guadalupian, and the event continued for a long time that is equal to the late Capitanian period.

Abstract:A 140km seismic reflection profile across the southern Dabie orogen and the Yangtze foreland reveals the detailed structures of the crust beneath the region. The generally north-depping crustal structures and the gently north-dipping Moho interface with several imbricate segment are referred to as the traces of a northward underthrusting of the Yangtze block. The Moho that underthrusts beneath the Dabie orogen and the south-dipping reflections of southern Dabie create a crossed reflection image, depicting the collisional structure beneath the collision of the Yangtze foreland and Dabie orogen.

Abstract:以南华北盆地户部寨第三系沙河阶组粉砂岩低渗透储层为例,总结了其中发育的5种类型构造裂缝组合,即:①南北向雁形张节理组成的共轭剪节理带;②东西向雁形张节理组成的共轭剪节理带;③缠结状多组剪切构造裂缝;④组合状交切的多组剪切构造裂缝及张裂缝;⑤散状无序排列的构造裂缝。在此基础上,建立光弹性试验构造物理模型,沿现应力场96°方向,均匀地对该模型逐步增加外载力。结果表明,沿各组合裂缝尖端分别形成对称于裂缝走向、且主轴垂直于裂缝的Ⅰ型等色线条纹;对称于裂缝走向、且主轴平行于裂缝走向的Ⅱ型条纹和斜交于裂缝走向的复合型(Ⅲ型)条纹。第①类组合裂缝尖端以Ⅰ型等色线条纹的拉张应力和张剪应力为主;第②类组合裂缝尖端以复合型(Ⅲ型)等色线条纹的挤压应力为主;第③、④和⑤类组合裂缝尖端的应力分布较为复杂。当模型外载荷接近1000kg时,裂缝尖端起裂,并开始发育显微裂缝,而当外载荷达1100-1200 kg时,沿裂缝尖端部位形成宏观裂缝,并开始扩展。5种类型的裂缝组合扩展发育程度由强至弱依次为:①,③,⑤,②,④。其中第①类共轭裂缝组合起裂最早,扩展最快,裂缝间的连通趋势最好,说明规则分布的构造裂缝组合,在垂直于外施加载衙时更易达到连通的目的。

Abstract:The large-scale morphology of the eastern margin of the Tibetan plateau can be divided into three zones, the Tibetan Plateau, Longmenshan and Sichuan Basin. To assess the large-scale erosional thickness and erosional rate of the region, we use digital elevation models (DEM) and fission-track thermorchronology to calculate the erosional thickness across the margin. We calculated the erosional rate of Longmenshan in the last 3. 6 Myr (ESR) , and the results indicate that the erosional thickness of Longmenshan is 1. 91-2. 16 km, and the erosional rate of Longmenshan is 0. 53-0. 60 mm/a. Based on results of simulation by flexural deflection, we inferred that the mountain building model of Longmenshan would have been constrained to both erosionally-driven uplift and tectonic shortening-driven uplift. Before 3. 6 Ma, the uplift of Longmenshan is driven by tectonic shortening related to the India-Asia collision, and after 3. 6 Ma the uplift of Longmenshan is driven by erosional unloading.

Abstract:According to the isotopic age data of inherited zircons in igneous and metamorphic rocks which occur at the surface and are derived from deep crust of the North China, Yangtze blocks and Qinling-Dabie orogenic belt, the paper is mainly reports some new information of Archean rocks (basement) and briefly discusses its geological significance. The deep crust of 6 areas on the northeastern, southeastern, northern and northwestern margin of the North China Block all show new information of Neoarchean, Mesoarchean and Paleoarchean magmatic events, and the deep crust of the southern margin demonstrates the existence of Paleoarchean magmatic event. In the histogram of isotopic data of early Precambrian of the North China Block, the highest peak is between 2. 45 Ga and 2. 6 Ga, where the 2. 5-2. 55 Ga culmination is most striking, suggesting that the magmatic event is strongest at the time span and the there was a possible important continent collision event then. While the other minor peaks at 2. 7 Ga, 2. 8-2. 85 Ga, 2. 95- 3. 0 Ga, 3. 1- 3. 15 Ga, 3. 3- 3. 4 Ga, 3. 45- 3. 5 Ga, 3. 6 Ga and 3. 8 Ga may reflect the different stages of the evolving magmatic activity. Information of Archean materials similar to that of the North China Block can be found on the surface and in the deep crust of the northern margin of the Yangtze Block. New data of Neoarchean and/or Paleoarchean from inherited magmatic zircons can be obtained from rocks derived from the deep crust in the middle-lower reaches of the Yangtze River, southeastern margin of the Yangtze block (corresponding to the former Jiangnan paleocontinent) and region of the southwestern margin of the Yangtze block. In the Qinling-Dabie orogenic belt, the rocks which are mainly out of the deep crust at many localities from east to west have given Neo-Mesoarchean evidence by the inherited magmatic zircons.

Abstract:对南昆仑缝合带中段西大滩盆北花岗岩,应用不同的年代学方法,测定岩浆结晶时代和构造热事件年龄,分析构造地貌演化过程。应用离子探针方法,测出西大滩盆北花岗岩的锆石U-Pb同位素年龄为196.4- 212.1 Ma,平均年龄204.1±2.6 Ma,代表岩浆侵位结晶时代。西大滩盆北花岗岩的黑云母K-Ar和Ar-Ar同位素年龄为134.47-145.3 Ma,指示晚期韧性剪切变形时代。应用矿物对热年代学方法,揭示出204.1-134.47 Ma、57. 67-26.0 Ma、26 Ma以来3期构造热事件,降温速率分别为6.46℃/Ma、4.91℃/Ma、3.84℃/Ma,对应的隆升速率分别为0.21 mm/a、0.16 mm/a、0.13 mm/a;说明134.47-57.67 Ma为缓慢降温和剥蚀夷平时期,对应的降温速率为0.64℃/Ma、差异隆升速率为0.02 mm/a。结合磷灰石裂变径迹测年和风火山群、五道梁群挤压缩短时代、区域伸展走滑起始年龄资料,推断昆仑山南部新生代山脉快速隆升发生于渐新世-中新世早期,估算隆升速率达0.26 mm/a。

Abstract:采用锆石U-Pb法对武功山穹隆复式花岗岩中广泛分布的花岗质岩石开展精细定年研究,结果表明:山庄、张佳坊和武功山岩体的锆石U-Pb年龄分别为460.5±1.5 Ma、427.9±1.2 Ma和428.0±1.0-462.3±2.3 Ma,属早古生代晚期花岗岩;而雅山、温汤和明月山等岩体的锆石U-Pb年龄分别为161.0±1.0 Ma、143.8±1.6 Ma和126.3±6.4.Ma,属晚侏罗世-早白垩世花岗岩。因此认为武功山穹隆复式花岗岩中花岗岩分属早古生代晚期及晚侏罗世-早白垩世岩浆活动产物。从一个侧面说明华南地区大地构造演化过程中可能存在早古生代晚期构造一岩浆作用事件及晚侏罗世-早白垩世构造-岩浆作用事件,为华南大地构造演化研究提供了新的依据。结合前人在武功山地区花岗质片麻岩中白云母40Ar/39Ar法定年(225-233 Ma)资料,说明本区韧性变形形成于晚i叠世,可能意味着武功山伸展构造的启动时间,而晚侏罗世-早白垩世花岗岩浆的形成及向上运移,使周围的岩石软化乃至部分熔融,使得围岩环境更有利于伸展构造发展,并在早白垩世最终形成武功山花岗岩穹隆伸展构造。

Abstract:The Triassic granites are widespread in the western Kunlun Mountains. However, the timing and tectonic regime that accounted for the granites are poorly known due to limited data in geochronology, geochemistry and structural geology. In this paper, we report our structure observation and U-Pb zircon ages of the two types of Triassic granites, and use these data to place chronological constraints on the tectonic evolution of the western Kunlun orogenic belt. The gneissic garnet-bearing granite was crystallized at 241 Ma, whereas the horblende-bearing granite emplaced at 228 Ma. In terms of structural characteristics and geochemistry of the granites in conjunction with previous studies, we interpret that the garnet-bearing gneissic granite (S-type) was formed during the collision between the Tianshuihai terrane and the Southern Kunlun terrane following the closure of a branch of the paleo-Tethyan ocean along the Mazha-Kangxiwa suture zone, the block hornblende-bearing granite was formed during post-orogenic extension. On the other hand, the granites of ca. 220-190 Ma in the southern Kunlun Mountains were part of a new magmatic arc, which was formed after the collision of the two terranes.

Abstract:The Nd-Pb isotope composition and source materials of the Cretaceous Quantou Group clastic sedimentary rocks and meta-granite in the Qing'an area,the Songliao Basin, are studied in this paper. The results suggest that the Cretaceous Quantou Group clastic sedimentary rocks and meta-granite are the product of clastic substances and their source materials consist of recirculated substance of the old crust. The source materials of the clastic sedimentary rocks and coarse-grained granite were derived mainly from the upper crust, while the fine-grained granite came primarily from the lower crust. The Pb isotope composition suggests that the clastic sedimentary rocks and coarse-grained granite are cognate products,but the fine-grained granite is different from either of them. The Nd isotope composition suggests that the physical circumstance and source materials of the Qing'an area are similar to those of the North China block, but different from those of the South China block.

Abstract:The superlarge Jinchang gold deposit is located in the connection between the Taipingling uplift and Laoheishan depression of the Xingkai massif in eastern Jilin and eastern Heilongjiang and the country rocks are metamorphic rocks of the Neoproterozoic Huangsong Group. In this region,the Yanshanian magmatism can be divided into 5 stages, the first three were mainly of diorite and granite and the latter two granitic porphyry and dioritic porphyrite, forming magmatic domes and cryptoexplosive breccia chimney, followed by large-scale hydrothermal alteration. Gold mineralization is closely related to the fourth and fifth phase of magmatism. Ores are mainly auriferous pyritized quartz vein, auriferous quartz-pyrite vein, auriferous metallic sulfide quartz vein, auriferous pyritized calcite vein. The age of the gold deposit is 119.40-122.53 Ma. The ore bodies are controlled by an integral tectono -magmatic hydrothermal alteration system, the metallogenic source came from the deep, and the metallogenic fluid was magmatic water with subsequent input of some atmospheric water. The metallogenic conditions were medium-high temperature, medium pressure, salinity slightly higher than the medium level, and the fluid of weak alkaline and weak reducing, that are of the K -Na -Ca2 -Cl--SO42- type. Gold was present in the fluid as complex compound, such as [Au(HS)2]- , [AuCl2]-, [Au(CO3)]- and [Au (HCO3)2]-. When the temperature and pressure lowered down and the fluid turned from acidic to weak acidic and further to weak alkaline, the complex compound cracked down and the gold precipitated.

Abstract:到目前为止,对辽宁庄河金矿尚没有做过系统的矿床地球化学和同位素年代学的研究。本文在成矿地质条件分析的基础上,对庄河金矿床的氢、氧同位素、硫同位素、铅同位素、碳同位素以及Rb-Sr同位素的组成特征进行了分析研究。氢、氧同位素组成表明成矿流体主要来源于岩浆热液,并与围岩发生了同位素交换;硫同位素和碳同位素组成表明成矿物质主要来源于地壳深部;矿石和花岗斑岩脉具有非常相似的铅同位素组成,暗示该矿床的形成和物质来源与此岩浆活动有密切的成因联系;石英流体包裹体Rb-Sr等时线年龄为143.0±5.8Ma,表明金的成矿期为燕山期。

Abstract:Based on former drilling data and our field investigations, writers studied the sedimentary environment, paleogeographic characteristics, sandstone bodies' thickness and spacial distribution of the Xishanyao Formation, which is the goal layer of prospect. Based on the epigenetic oxidation degrees of various layers of the Xishanyao Formation, the distribution and spacial shape of interbedded oxidation zone were ascertained. The sandstone petrological and petrochemical characteristics of the goal layer suggests that there are close relations between sandstone porosity, density and its texture-construction, and that the variations of the secondary minerals and the contents of chemical elements such as Fe, CO2, C (organic carbon), S, U, Th, Se, Mo, V et al. are closely related to the oxidizing action of groundwater, and agree with the variation rules of aqueous uranium deposit. Based on the studies above, the oxidated sand body was confined, which has the depth of bottom footwall of less than 300m and the thickness of 50-100m. The length of the oxidation zone front is up to 60 km. Many uranium mineralization and selenium mineralization points were found in the oxidation zone front. Therefore, it is suggested that the region has good prospect for the uranium deposits of sandstone-type.

Abstract:The Western Sichuan foreland basin is not only a typical foreland basin in west China, but also an important tight sandstone gas area in China. Fluid cross-formation flows took place in the foreland basin. Fluids within the permeable layers of the Second and Forth Members of the Upper Triassic Xujiahe Formation have flowed cross the impermeable layers of the Third and Fifth members of the Upper Triassic Xujiahe Formation to the permeable layers of the Jurassic Ziliujing Formation, Jurassic Qianfoyan Formation, Shaximiao Formation, Suining Formation and Penglaizhen Formation. The fluid cross-formation flow has made Jurassic sandstone be secondarily dissolved by acidic water and become better reservoir rocks. Besides, it has afforded a natural gas source for the formation of Jurassic gas pools. The gas reservoirs in the foreland basin are characterized by chimney effect of gas activity, early accumulation and late formation of natural gas, and abnormal high pressure. Deep-basin gas is the basic state of the early accumulation of natural gas in the Upper Triassic (mainly the Second and Forth Members of the Xujiahe Formation) in the foreland basin and the basis for late-stage formation of gas reservoirs. Such areas are called rich-in-gas areas in this paper. They are the requisite for the forming of late-stage gas pools. Natural gas reservoirs were formed because early-stage rich-in-gas areas were broken due to uplifting of the crust to produce fluid cross-formation flows, and as a result natural gas was migrated and cumulated at a very high speed and in a large quantity through relatively narrow paths. Such formation of natural gas is called explosion accumulation. This type of gas accumulation generated Upper Triassic fracture-readjusted gas pools and Jurassic gas pools, both of which are not secondary gas reservoirs. Identification and evaluation of the early-stage gas accumulation and related rich-in-gas areas are the key issue and also a difficult problem in the future as regard to exploration of gas pools in the foreland basin of western Sichuan.

Abstract:Along the south and north feet, as well as in individual valleys of the Ayila Rigyu Mountains, Ali area, Xizang (Tibet) there are four sets of early Pleistocene glacial deposits. Based on the stratigraphic sequence of the glacial deposits and the glacial ages determined with the electron spin resonance, the four glacial events in the early Pleistocene are named the Zomda glacial epoch (1161- 952 ka BP), the Ayila Rigyu glacial epoch (762-730 ka BP) , the Xuelang glacial epoch (336 - 211 ka BP) and the Nongqiong glacial epoch (105 - 15 ka BP). Comparisons were done between these glacial epochs and other glacial epochs in the Qinghai - Xizang Plateau and some other areas. The glacial epochs are characterized by great mountain glaciers, ice caps, piedmont glaciers and medium- to small-scale valley glaciers. The existing glaciers had glacial advance in the Holocene and the glaciers have clear recession in the present period.

Abstract:额济纳绿洲位于我国极端干旱区,该地额济纳剖面(41°46.36'N,101°09.26'E)的地层含1层现代流动沙丘、8层古流动沙丘、18层古半固定沙丘、14层古固定沙丘、2层沙质弱成土和2层沙黄土-亚沙土。根据对该剖面11个14C年代样品测试和263个粒度样品的分析结果,本文确定了这套以沙丘沙沉积为主的沉积序列主要是2.5 ka BP以来气候一风沙地貌过程的产物,并详细讨论了自那时以来不同沉积类型的粒度及其Mz、σ和SC/D等分布规律和成因问题。这一研究结果表明:①额济纳剖面古流动沙丘沙、古半固定沙丘沙和古固定沙丘沙无论在粒度组成还是在Mz、σ分布上,都分别与现代流动沙丘沙、半固定沙丘沙和固定沙丘沙颇为相似,这为该剖面沙丘类型的划分提供了重要依据;相对这三类沙丘沙而言,沙黄土-亚沙土和沙质弱成土的沙物质含量显著降低,而粉沙和粘土含量明显增高,显示出沙丘嗣后的较强的成土作用和一定的土壤化过程。②该剖面古流动沙丘沙或古半固定沙丘沙与上覆的古固定沙丘或沙黄土-亚沙土或者是沙质弱成土可以构成11.5个沉积旋回,其每一个旋回又表现为颗粒由粗变细,Mz(Φ)、SC/D由小到大和σ显示的由分选好到变差的粒度旋回变化,代表了一个“沙漠化”时期被嗣后的“绿洲化”时期替代的正逆交替变化过程。③2.5 ka BP以来额济纳绿洲经历了11.5个旋回的“沙漠化”与“绿洲化”的生态环境变迁,在时间上具有若干百年时间尺度的环境变化,其驱动因子主要与自那时以来东亚冬夏季风交替演变有关。