Abstract:Abstract：The Qiangtang basin is now one of the hot areas of petroleum exploration in China. Recent geophysical and petroleum geological survey and INDEPTH-3 deep exploration have revealed the following points: (1) In the basin, hydrocarbon source rocks, reservoir rocks and seal rocks, as well as their association are quite good, with local structures well developed, which is favorable for the formation and preservation of petroleum accumulations, and faults will not constitute a vital problem； the main target in the future work will be the Upper Triassic-Middle Jurassic intermediate teｃtonｉc layer.(2)A new tectonic division into the second- and third-order structures in the basin has been made and the existence of the Central Qiangtang uplift has been negated； the main structures at the surface of the basin are oriented in a NW-SE direction and characterized by the form of “three subbasins and three rises” ａｎｄ “a deep subbasin”, among which the main subsidence zone and its two sides are the most favorable areas. (3)The intense interaction between crust and mantle in the area led to repeated volcanic and thermal activities, which has significanｔ influence on petroleum prospect evaluation in the northern part of the basin； whereas the southern part of the basin has been subjected to less deep-seated thermal influence because of its thick sediments and therefore is more favorable for petroleum finding. (4)It is a task of top priority to ascertain the physical parameters of deep-seated rocks, mode of occurrence of petroleum, sources of hydrocarbon and coincidence between the upper and lower structures. The focus should be on intensifying the investigation and evaluation of sites of interest.(5)The petroleum prospects in the Tertiary Lunpola continental basin should not be ignored because petroleum might be accumulated in marine rocks on its two sides.

Abstract:Abstract：The shallow tectonic system in the northern Tarim basin adjacent to the southwestern Tianshan Mountains consists of the Kashi depression, Kalpin Tagh thrust nappe tectonic belt and Kuqa foreland depression thrust belt, which are distributed in the form of 1－3 rows parallel to the orogenic belt in the mountain front. It is also a thrust nappe system composed of the basal detachment fault flat and fault ramp, showing distinct E-W-directed transverse segmentation. The deep tectonic system is marked by a set of NW-trending faults, which divide the area into four fault slivers. The authors systematically study the deep transverse tectonic system in the area in the contexts of the structural layers, gravity and aeromagnetic anomalies and density of earthquake occurrences and recognize the depths of detachment surfaces of the lithospheric layers by using the statistical results of the depth and frequency of the earthquakes. On that basis, the authors discuss the regional NW-trending transverse tectonic system in detail. In the paper, the Karayulgun fault belt and Korla fault belt are selected for ｔｈｅ study ｏｆ the transformation relation between the transverse structure and shallow structure and finally a geometric and kinematic model of the fault slivers in the northern part of the Tarim block is proposed, i.e.：the Tarim block is “forced” to be subducted as the NW-directed movement of its deep part is hindered and constrained by the ancient southwestern Tianshan, thus resulting in decoupling of the lithospheric crust, activation of the original transverse tectonic system (NW-trending fault belt) and subduction of the subducting system in the form of fault slivers； in the process of subduction, the detachment of the lithospheric crust and activation of the transverse structure started near the “constraining body” (southwestern Tianshan) and progress toward the interior of the Tarim basin (northern part), and therefore the difference in subduction state between the fault slivers is more obvious and the transverse segmentation is more prominent toward the orogenic belt. It is just because the subduction of the Tarim block in the form of fault slivers that segmentation of the piedmont depression thrust belt (and Tianshan belt) takes place.

Abstract:Abstract：The Ordos basin is a large Mesozoic intracontinental basin superimposed on the Paleozoic North China craton. The Late Mesozoic-Cenozoic were an important modification period of the basin, during which significant changes in tectonic regimes occurred and tectonic belts of different trends and styles were formed around the basin. The main phase of the Yanshanian movement that took place during the Mid-Late Jurassic is of great significance for the shaping and development of the Ordos basin. Compressive tectonic belts surrounding the Ordos basin were mostly formed during this Yanshanian phase. During the Early Cretaceous, in response to the tectonic stress regime transition, the Ordos basin was subjected to week extension, and extensional deformation was localized along its SW margin, resulting in the development of the Liupanshan paleo-graben. During the Cenozoic, tectonic deformation mainly occurred around the Ordos basin, resulting in the formation of the grabens. During the Neotectonic movement since the late Miocene or early Pliocene, owing to the influence of the rapid uplift of the Qinghai-Tibet Plateau and its eastward extrusion, the Liupanshan fold belt on the southwestern margin of the Ordos rose rapidly, while extensional deformation and differential uplift and subsidence of the blocks took place in other peripheral zones of the basin. Finally, the paper discusses the basin modification in different tectonic stress regimes and some basic tectonic problems in the study of the Ordos basin.

Abstract:Abstract：The Late Cenozoic geomorphologic and sedimentary features in the West Kunlun Mountain front record the uplift process of the West Kunlun Mountains and the western margin of the Qinghai-Tibet Plateau. Based on geomorphologic and paleomagnetic studies, the Late Cenozoic tectonic movement in the West Kunlun are discussed. At about 25 Ma, significant change took place in sedimentary features in the West Kunlun Mountain front, reflecting that the West Kunlun began to be uplifted, and at about 5 Ma, molasse developed in the West Kunlun Mountain front, indicating that the West Kunlun began to be uplifted rapidly. Paleomagnetic results show that marked clockwise rotational movements occurred in the Eocene-Miocene, while vertical movements resulting from horizontal compression have predominated in the Quaternary and no marked rotational movement during this period. The downward incision of the rivers in the West Kunlun at about 1.2 Ma gave rise to terraces. Since the Mid-late Quaternary, the magnitude and frequency of the tectonic uplift have increased, and a rapid tectonic uplift event took place in the middle Holocene (at about 5 ka).

Abstract:Abstract：The Luonan-Luanchuan fault zone on the northern margin of the Qinling Mountains is a convergence belt between the North China plate and Qinling orogenic belt with the natures of SW-NE-directed subduction and sinistral strike-slip motion. It shows an association style of imbricate structure and duplex structure. The structures of different natures on the northern margin of the Qinling Mountains make up a regular pattern, with their distribution direction and kinematic mode coinciding with the kinematic features of ｔｈｅ convergence plate. The results of deformation analysis indicate that the deformed rocks in the area are mainly the product of the middle and upper crust. The triaxial ratio of rock finite strain is X∶Y∶Z = 8.86∶4.32∶1 and the strain ellipsoid is flat-ellipsoidal. The convergence factors are as follows： in the Luonan area the direction of plate convergence is 22° and the angle between the plate convergence direction and plate boundary is 73° and in the Luanchuan area the direction of plate convergence is 31° and the angle between the plate convergence direction and plate margin is 82°. This shows ｔｈａｔ the collision and convergence between the Qinling orogenic belt and the southern margin of the North China plate have the typical features of oblique convergence.

Abstract:Abstract：The Dayishan fault, flaked on the north and south by the N-S-trending Shuikoushan-Xianghualing tectonic zone, belongs to the southeastern segment of the NW-trending Shaoyang-Chenzhou fault. On the basis of the characteristics of tectonic deformation, combined with the regional tectonic setting and evolution, the authors consider that the Dayishan fault experienced at least three tectonic movements in the Meso-Cenozoic, which are from early to late times the Indosinian sinistral strike-slip movement, Yanshanian dextral strike-slip movement and Himalayan (?) sinistral strike-slip movement. After an intensive analysis of the ages of the N-S-trending structure and NNE-trending regional structure and their interaction, the authors propose the following new idea of the genesis of the N-S-trending structure：as the basement sinistral strike-slip movements of the NW-trending Dayishan fault and Xianghualing-Yangmingshan fault occurred in the Indosinian movement, the E-W compressional stress field derived by the strike-slip motion and sinistral drag produced by the strike-slip motion led the regional NNE-directed lineament to rotate counterclockwise, thus forming the N-S-trending structure. Further analysis suggests that the Indosinian was probably a period of the strongest movement of the main NW-trending faults in eastern Hunan in the Mesozoic, and that sinistral strike-slip motions of several NW-trending faults in the Indosinian ａｒｅ probably one of the formation mechanisms of the Xｕefengshan arc structure and the Qiyang “epsilon”-type structure.

Abstract:Abstract：The Asian continent (mainland China and its adjacent areas) is a composite one formed by multi-stage accretion and collision of a number of microcontinents (cratons) and blocks of different origins. The Hercynian-Indosinian cycle and Neo-Tethyan cycle played a decisive role in its formation. At the end of the Jurassic and the beginning of the Cretaceous, the Neo-Tethys ocean (which is called the Mid-Tethys by some people) closed ａｎｄ the embryonic Asian continent occurred. At the end of the Cretaceous, the Neo-Tethys ocean was consumed and the Asian continent originated；therefore the Cretaceous was an important transition period of the plate tectonic evolution of China and its adjacent areas. This paper discusses this transition in the contexts of the transitions of geodynamic system and tectonic framework, appearance of the NE-trending neogenic structures and diversity of orogeny. This transition is mainly manifested by the transformation of north-south differentiation to east-west differentiation in the region during the Cretaceous. The western part is characterized by the tectonic inheritance, while in the eastern part the neogenic structures played the main role. Geomorphologically, the region was high in the east and low in the west in the Early Cretaceous, while the present-day geomorphologic feature of being high in the west and low in the east began to appear at the end of the Cretaceous. The “basin-and-range” system also began to change significantly in the Cretaceous, which suggests that the margin of the East Asian continent was disintegrated progressively in response to its creep and dispersion toward the Pacific plate, and then the tectonics in the interior of the continent became increasingly complex. This case study further indicates that we must adhere in the tectonic concept of mobilism and reconstruct the regional tectonic evolution with the idea of dynamic evolution.

Abstract:Abstract：The authors analyzed early Pleistocene lacustrine strata at Zhagenjialong (1919.6 ka B．P．), in borehole K5 (1135.9 945.4 ka B．P．) and on the west bank of the Yeniu River (1548.2－765.4 ka B．P．) and fossil plants and sporopollen data in various section in early Pleistocene lacustrine strata at Zhagenjialong. The analytic results show that in the early part of the early Pleistocene there occurred a subtropical hilly coniferous forest vegetation landscape in the source area of the Yellow River, and that in the strata woody plants predominate, mainly including needle leaf plants such as Picea, Pinus, Abies and Tsuga, indicating a flourishing period of animal and plant growth in the source area. At the beginning of the late Early Pleistocene, pollen of arborous plants was rapidly reduced and even all disappeared, and pollen of herbaceous plants increased significantly. At the end of the late part, sporopollen was diluted, with pollen of herbaceous plants predominating, showing a landscape of desert steppe vegetation. The formation of the present eco-geological environment in the source area of the Yellow River is the inevitable result of geological evolution.

Abstract:Abstract：Quaternary glacial deposits of the Zanda basin and its surrounding mountains may be divided in space distribution into：① glacial deposits in U-shape valleys and foothills in the basin and its surrounding mountains, ② glacial deposits in deep-incised valleys around the basin, ③ glacial deposits on the basin surface, ④ glacial deposits on high terraces of river valleys and in gullies of the basin, and ⑤ glacial deposits in piedmont zones of mountains around the basin. Glacial deposits in different areas differ markedly with respect to the gravel composition, roundness, textures and structures, geomorphologic features. The Quaternary glacial development in the region may be divided from early to late times into the periglacial stage, glacial advance stage, biggest glacial stage and glacial retreat stage according to the features and distribution of glacial deposits. The glacial types corresponding to these stages are the valley, piedmont and ice-cap glacier development stage, ice field glacier development stage and ice-cap, valley glacier and piedmont glacier development stage. The existing data indicate that the Zanda basin and its surrounding mountains are areas where the most abundant, complete and continuously occurring and best-preserved Quaternary glacial deposits are found on the Qinghai-Tibet Plateau. This research provides valuable basic data for the study of Quaternary glaciers in this region and the Qinghai-Tibet Plateau, division and correlation of glacial epochs, establishment of climatostratigraphy and climatic and paleoenvironmental studies.

Abstract:Abstract： On the basis of the high-density sampling and organic carbon isotope analysis, combined with the grain size and lithologic studies, the paleoclimatic and paleoenvironmental evolution in the Jiangling area of the Jianghan plain during the past 9 ka is reconstructed. There was a relatively warm and wet climatic environment at about 9.0－6.31 ka , which tended to be dry at the late stage；a cold and dry climatic environment occurred at 6.31－4.97 ka , which reached a culmination at 5.78 ka；the climatic environment again became warm and wet at 4.97－2.50 ka , during which limnic peat was developed at 3.44－2.50 ka；marked temperature lowering at 3.36, 3.11, 2.93 and 2.71 ka is recorded；the temperatures have been relatively low since 2.50 ka, representing a cold epoch. The climatic changes in the Jiangling area over the past 9 ka are coincident with the research information from domestic in the neighboring areas but also show regional difference.

Abstract:Abstract：The construction of a 3D geological configuration model is one of the main contents of urban geological investigations that are being carried out in Hangzhou City. The construction of an accurate model mainly depends on the accurate inter-borehole stratigraphic correlation；so it is a very important subject to determine an appropriate stratigraphic correlation method suitable to local areas. In this paper, an analysis is made on the traditional correlation method and the method of high-resolution stratigraphic correlation of the Quaternary used in the 1:250000 regional geological mapping of the Hangzhou City Sheet. According to the theory of high-resolution sequence stratigraphy and criteria of correlation, combined with the sedimentary characteristics of the estuary area where the Hangzhou-Jiaxing-Huzhou plain is located, a new inter-borehole Quaternary stratigraphic (rock) correlation method suitable to this area is put forward.

Abstract:Abstract：Based on systematic studies of major and trace element and Sm-Nd isotopic geochemistry, the Precambrian to Triassic clastic sedimentary rocks in the Garzê-Songpan block and Longmen Mountains have been finished. Ｔhe rocks are determined to be grａywacke and arkose and their material source should be a mixture of mafic and felsic materials and quartz+carbonate. The total REE contents of the rocks increase gradually and negative Eu anomalies become more evident from Precambrian to Triassic rocks, which may imply intensifying crustal anatexis. The tectonic setting was relatively stable during the Late Paleozoic；therefore there appear pronounced negative Ce anomalies. The Nd model ages range between 1.6 and 2.4 Ga；this age range is similar to that of the Yangtze craton, South Qinling and North Qinling and quite different from that of the North China craton. Therefore, the provenance of the sedimentary rocks in the Garzê-Songpan block and Longmen Mountains is the western margin of the Yangtze craton, and the block is a tectonic unit that developed on the basis of the Yangtze craton. The correlation between provenances of the western Yangtze craton shows that the source materials of the sedimentary basin should mainly be the Neoproterozoic tectonic layer and secondarily the Archean and Paleoproterozoic tectonic layers. Triassic clastic sedimentary rocks may contain Late Paleozoic mafic mantle-derived, and the spatial distribution of the Nd isotopic composition indicates that there occurred denudating areas in the east and north and deep-water depositional areas in the west and south in the Garzê-Songpan basin during the Triassic.

Abstract:Abstract： The South Zhuguangshan pluton is a composite granite batholith formed in the Caledonian, Indosinian and early Yanshanian periods. This paper mainly discusses early Yanshanian granites, namely, the Middle Jurassic Sanjiangkou sequence. The sequence is composed of five rock-units, and the rock type is hornblende-biotite monzogranite-biotite monzogranite-two-mica monzogranite. The earlier units contain abundant mafic micro-enclaves, and the petrographic study of the enclaves indicates the crust-mantle mixing origin of the granitic magma. The average content of SiO2 increases from 68.95% in the early-formed granite units to 76.3% in the late-formed granite units. The rocks are alkali-rich. Their Na2O+K2O ranges from 7.11％ to 8.24%, with an average of 7.73% and K2O＞Na2O, and their ASI values range from 0.92 to 1.19, with an average of 1.05；so they belong to the magnesian-ferruginous, metaluminous-peraluminous, high-K calc-alkaline series. The rocks are of light REE-enriched type, with a moderate ΣREE content of 213μg/g and strong Eu depletion, and have negative anomalies of Ba, Nb, Sr, P, Ti, Eu and Ba and positive anomalies of Rb, U, Th, Nd, Zr, Sm and Y, which indicate an intracontinental tectonomagmatic environment. The rocks have ISr values of 0.7115 to 0.72466, εNd (t) values of －10.0 to －12.6 with an average of －10.97 and t2DM ages of 1.75 to 2.0 Ga with an average of 1.84 Ga. The average age is close to that (1.7 to 1.8 Ga) of Mesozoic granites in the Nanling Mountains, indicating that the rock-forming materials were mainly derived from the Mesoproterozoic crust. The tectonic setting discrimination diagrams based on multiple oxides and trace elements suggest that granites of the Sanjiangkou sequence formed in a post-orogenic extensional environment during the transition from compressional orogeny to non-orogeny. The authors consider that the early Yanshanian tectonic setting in the Nanling Mountains and even South China is post-orogenic rather than an intracontinental rift.

Abstract:Abstract：This paper reports the LA-ICP-MS zircon U-Pb dating results of garnet-plagioclase pyroxenite in the Wuhe complex in the Bengbu uplift. The cathodoluminescence (CL) images of zircons from the garnet-plagioclase pyroxenite show three textural types of zircon, i. e.：euhedral zircon of homogeneous absorption, zircons with a distinct internal structure and typical core-rim structure and euhedral zircons with typical growth zones. The zircon U-Pb dating of spots with different intensities of zircon absorption indicates that their 207Pb/206Pb ages range from 1783±8 to 1895±8 Ma and that the weighted mean age of ４９ analyzed spots is 1833±8Ma. This result suggests that the Wuhe complex was formed in the Paleoproterozoic, which is in agreement with the age of formation of the central orogenic belt of the North China craton and the age of high-pressure granulite-facies metamorphism in Jiaodong, and further implies that the Wuhe complex should belong to the basement of the North China craton．

Abstract:Abstract：The original Alxa Group-complex consists of metamorphic strata and deformed orthogneisses of different ages, geneses, tectonic styles and metamorphic grades；so it is not suitable for a lithostratigraphic unit and should be disintegrated and redefined. Based on recent studies, the original Alxa Group-complex may be divided into three metamorphic stratigraphic units and two deformed orthogneiss complexes. The oldest lithostratigraphic unit in the area is the Diebusige Group-complex, which consists of high-grade metamorphic supracrustal rocks and is the basement rock series in this area. Preliminary zircon SHRIMP U-Pb dating suggests that the Diebusige Group-complex formed at ~2700 Ma and is considered to be of Neoarchean age. The newly established Bayan Ul Formation-complex, which is principally composed of metavolcanic rocks, is a volcanic rock series in this area. Its newly obtained ages are 2264 and 2271 Ma, indicating a Paleoproterozoic age. The redefined Alxa Group-complex, which consists predominantly of meta-clastic rocks and meta-carbonate rocks, is a continental-margin sedimentary series and formed in the late Paleoproterozoic or still later. The Boluosutanmiao tonalitic-granitic gneiss complex is composed of early-stage tonalitic gneiss and late-stage granitic gneiss. The early-stage tonalitic gneiss formed at ~1.8 Ga and the late-stage granitic gneiss formed approximately during the Paleozoic. The Bijigetai granodioritic gneiss complex is mainly composed of hornblende-plagioclase gneiss and biotite-plagioclase gneiss and the preliminary isotopic dating indicates that the main stage of this complex occurred in the Jinningian at 0.8－1 Ga.

Abstract:Abstract：The Muchen intrusion and its adjacent Xishantou Formation volcanic rocks and subvolcanic rocks are intimately associated in space and their formation ages are close. Their rock types are all intermediate-acid and have a similar petrochemical composition, all belonging to a weakly alkaline rock series. The REE distribution patterns for various rock types are in the main consistent with the exception of Eu and so are the trace element distribution patterns. This indicates that they are products of evolution of consanguineous magma. They display similarities and consistency in respect to rock types, rock chemistry and REE and trace element geochemistry, and in addition, all their magmatic evolutions show a reverse sequence, which demonstrates that they are a consanguineous volcanic-intrusive rock association. Based on the Jurassic／Cretaceous boundary age of 145.5±4.0 Ma published by the International Commission on Stratigraphy in 2004, combined with the genetic relationship between the Muchen intrusion and its adjacent Xishantou Formation volcanic rocks, it seems more reasonable to define the age of the Muchen intrusion at Early Cretaceous.

Abstract:Abstract：In this study the fractal method is for the first time used to analyze the Fuchashan tectonite in the Tanlu fault, Feidong, and the results show that the boundaries of the dynamically recrystallized quartz grains in the Fuchashan ductile shear zone in the Tanlu fault are statistically self-similar and have distinct fractal features. Using the “perimeter-diameter method”, the authors conclude that, with an increase in degree of mylonitization of the samples, the fractal dimension value increases progressively from 1.204, 1.213 and 1.222 to 1.229 and the corresponding diameter of the dynamically recrystallized quartz grains is reduced from 33.79, 26.00 and 22.82 μm to 15.01 μm. Comparison between two different calculation methods shows that the corresponding strain rate increases gradually from 4.837×10-13s-1, 7.688×10-13s-1, and 9.682×10-13s-1, to 2.031×10-1２s-1. The metamorphism in the study area is generally of high greenschist to low amphibolite facies, and the metamorphic temperature is about 500 ℃. Comparing the results of this study with the previous conclusion, the authors conclude that the Kruhl geothermometer is suitable for the study area, while the Takahashi strain rate meter is unsuitable for the ductile shear zone formed at relatively deep crustal levels.

Abstract:Abstract：Xinjiang and its neighboring countries and regions are an important component part of the gigantic Central Asian metallogenic megaprovince. Typical deposit types such as kuroko deposits，porphyry deposits，massive sulfide deposits，volcanic-hosted Au deposits，ore deposits related to alkali-rich intrusive rocks and sandstone Cu deposits have been discovered in the metallogenic megaprovince. Especially，the discovery of several Large and super large deposits in the metallogenic megaprovince in recent years indicates that there are unique metallogenic features and huge ore potentials in the Central Asian metallogenic megaprovince. Through analyzing and comparing the metallogenic characteristics of the large and superlarge ore deposits and characteristics of the typical deposits in Xinjiang and its neighboring countries and regions，the authors put forward some opinions about the prospecting targets in Xinjiang and its neighboring regions.

Abstract:Abstract：The Shuiyindong gold deposit was found in the middle 1990s and has now become a superlarge stratabound gold deposit through nearly ten years of exploration. The orebodies occur in the stratified or stratoid shape in high-porosity bioclastic limestone of the Upper Permian Longtan Formation within 300 m near the axis of the Huijiabao Anticline. The shape of the orebodies is similar with that of the anticline. They are strictly controlled by carbonate rocks, and both their hanging wall and footwall consist of claystone or silty claystone, with clear-cut boundaries. The gold mineralization is represented by the association of silicification, dolomitization and pyritization. Silicification and dolomitization are metallogenic preconditions. The possibility of carbonate mineralization and gold grade of ores depend on the hydrothermal alteration of pyrite and its alteration intensity. The deposit is characterized by the large number of orebodies, small thickness and high grade, and a single orebody may reach a medium-sized deposit scale. This deposit has the features of medium- and low-temperature, ultrahigh-pressure hydrothermal mineralization. Gold is hosted by arsenic-bearing pyrite zones growing along the cores of idiomorphic pyrite.

Abstract:Abstract：The imaging spectroscopic identifying and mapping technique is one of the advanced new techniques that are now mainly developed in land and resource survey and monitoring. The main purpose of this study is to apply this technique in land and resource survey. For this purpose, the authors have studied some key technical problems arising in the utilization of the imaging spectroscopic technique for mineral identifying and mapping. The spectral features and variations of two important alteration minerals－muscovite and chlorite－are analyzed. Taking for example HyMap data from the Huangshan area, East Tianshan Mountains, Xinjiang, this paper introduces the application of some systematized imaging spectroscopic data processing techniques such as MNF trans－formation, pixel purity index (PPI) and n-dimensional visualized identification (NDVI) of endmembers in the identification and mapping of typical alteration minerals.

Abstract:Abstract：A series of molecular fossils, including n-alkanes, pristine, phytane, extended tricyclic terpanes, hopanes and regular steranes, have been identified from the Shibei dinosaur fossil site－Early Jurassic red beds－in Gongxian, Sichuan, through GC/MS analysis. These fossils are supposed to be derived from lower thallophytes and aquatic and terrestrial higher plants. The features of these molecular fossils are used to study the paleoenvironment during the dinosaur age. The Pr/Ph suggests that the sedimentary environment at the burial site of the dinofossils should be a limnetic, non-reductive lake. High-molecular-weight (>C21) n-alkanes in the studied samples are dominated by C25 n-alkanes related to aquatic macrophytes,, and in addition, C27－C31 n-alkanes derived from terrestrial higher plants are also present. This suggests that aquatic higher macrophytes flourished in the lake of the study area in the Early Jurassic, while woody plants and herbaceous plants grew in the watershed around the water body. This study shows that molecular fossils have a potential in reconstructing the paleoenvironment.

Abstract:Abstract：The sequence stratigraphy and sedimentary system of the Paleogene Shahejie Formation of the Raoyang subbasin have been studied by employing seismic, well log and drilling core data. On the basis of the identification and correlation of sequence stratigraphic units, the Shahejie Formation has been divided into six third-order sequences and 14 system tracts. The paper analyzes the main cause of formation of each sequence in detail and sums up different characteristics of various sequences. In addition, the sedimentary characteristics and sedimentary systems in each sequence are analyzed and the controlling effects of sequence development on the sedimentary systems are pointed out. During the study, the authors also studied the types of oil-gas reservoirs and characteristics of oil-gas accumulation in different system tracts of a sequence, and on that basis, they indicate the most favorable oil-gas reservoir types possibly developed in various system tracts.

Abstract:Abstract：Study of the sedimentary characteristics of a typical outcrop section in the south of the Mesozoic Bohai Gulf area and its surrounding areas and lithofacies and paleogeography in the central part of the study area shows that the Mesozoic Bohai Gulf area consists of a series of downfaulted basins controlled strictly by faults, where there is mainly developed an alluvial fan-river-lake sedimentary system lakeshore-shallow lake, beach-bar and semi-deep lake subfacies occurring inside the lake. The alluvial fan-river sedimentary system evolved upward into a lake sedimentary system and then again gradually evolved into an alluvial fan-river sedimentary system. The compressional amalgamation of the Siberian plate,Yangtze plate and North China plate in the Eurasian tectonic domain played a main controlling role in the Jurassic basin filling in the Bohai Gulf area and the strike-slip motion of the Tanlu fault played a main controlling role in the Cretaceous basin filling in the gulf area.

Abstract:Abstract：According to the core and well log data and lithologic and electric correlation, high-resolution sequence stratigraphic study has been conducted on the fan deltaic reservoirs in pay sets 4 to 8 of the Third Member of the Shahejie Formation in the Huzhuangji oilfield. The criteria for recognition of different orders of cycle boundaries and cycle types are established, and the studied section is divided into one long-term cycle and six medium-term cycles. The correlation principle and method of short-term stratigraphic cycles are determined and the framework of correlation of short-term cycles is established according to the controls of medium-term cycles on the deposition of sandbodies and relationship between the geomorphological change and types of short-term cycles parallel or perpendicular to the direction of the provenance. The distribution characteristics of sandbodies and reservoir properties in short-term cyclic sequences are notably different in different phases of a medium-term base-level cycle, which is the main cause responsible for serious reservoir interlayers or plane heterogeneities. It should be taken into account when the sequences of strata which are to be exploited are distinguished in detail.