A Climatic Sequence Stratigraphic Model in the Terrestrial Lacustrine Basin:A Case Study of Green River Formation,Uinta Basin,USA

In recent years, with the development of terrestrial sequence stratigraphy, more attention has been focused on the study of the terrestrial lacustrine sequence stratigraphic model globally. Different viewpoints are preferred by researchers. Under the guidance of the theory of sequence stratigraphy, the findings of this paper indicate that climate is a major factor controlling the formation of the fourth-order sequence, based upon the study of the sequence stratigraphy in the Green River Formation of the Uinta basin in the USA. It also divides the fourth-order sequence in the terrestrial lacustrine basin into two system tracts： the wet （rising） half-cycle and the dry （falling） half- cycle, establishing a new-style fourth-order sequence stratigraphic model for the terrestrial lacustrine basin, that is, the climate-genetic sequence stratigraphic model. As a result, the theory of sequence stratigraphy is greatly enriched.

Sequence Stratigraphic Modeling of Sedimentary Basin: Conceptual Model and Application to Erlian and Yinggehai Basins, China

A quantitative two-dimensional model of sequence stratigraphy is formulated to simulate the development of sequence architecture in sedimentary basins. The model takes into account sea level change, tectonic subsidence, compaction of sediments, flexural isostatic compensation, erosion and sedimentation. It may be used to test sequence stratigraphic model, to analyze the development of sequence architecture and sequence boundaries, and to predict facies distribution in basins. The computer model, combined with backstripping technique, is cali- brated to model the sedimentary filling of the Early Cretaceous Erlian basin and the Tertiary Yinggehai basin. The study shows that the development of high order sequences in the basins was closely related to the multiple stretching and inversion. The development of the progradational sequence set of the Yinghuang Formation in Yinggehai basin formed in synrift period was mainly controlled by a large amount of sediment input high fluctuation of sea level and gradual subsidence of the basin.

HIGH-RESOLUTION SEQUENCE STRATIGRAPHIC ANALYSIS OF THE PERMIAN IN THE WESTERN SHANDONG AND HUAINAN-HUAIBEI COALFIELDS

The sedimentary characteristics and their combination succession of the Permian in the Shandong nd Huainan-Huaibei coalfields are analyzed. The mid-and short-term stratigraphic base-level cycles are identified. High-resolution sequences are divided based on the above results. The study shows that the stratigraphic base-level cyclic method is an efficient way in the determination of the high-resolution sequences, especially in the classification of tbe terrestrial and transitional depositional succession.

EXTENSION OF SEQUENCE STRATIGRAPHIC MODELAND SEQUENCE STRATIGRAPHIC ANALYSIS IN LIMNIC DEPOSITIONAL BASIN

The architectural patterns of sedimentary succession are diverse in different depositionalbasins. The sedimentary architecture and geological condition of such basins asepicontinental sea, intraplate limnic basins, etc., differ cIearly from those of continentalmargin basin. Extension, complement and perfection of sequence stratigraphic models are needed in the studies of various depositional basins based on the classical sequence model. This paper, for this reason,expounds the thought, principles of sequence division, methodology and technology of the study of sequence stratigraphy in epicontinental and limnic basins.

Distribution regularity of the Ordovician reef-bank reservoir inside sequence stratigraphic ework in central Tarim Basin

Based on the integrated study of the outcrops, the seismic, drilling and logging data of Lianglitage formation in central Tarim Basin, the sequence stratigraphic framework of the platform margin is built, and the Lianglitage formation is divided into 3 third-order sequences. The vertical pattern and lateral distribution for carbonate reef-bank reservoir in sequence stratigraphic framework are analyzed. The reef-bank reservoir mainly developed in highstand system tract of sequence Ssq2, and distributed along the carbonate platform margin of the Middle-Late Ordovician in central Tarim Basin. The mudstone mound, organic reef, granule bank are vertically stacked. Laterally, the area of well shun3-shun4-shun2-shun6 are characterized by multiphase bank reservoir overlapping, and the area of well TZ82 -TZ44 - TZ161 -TZ24 - TZ26 are characterized by multiphase organic reef and bank overlapping. The reef-bank complexes in sequence Ssq2 are the main targets of exploration in central Tarim Basin.

Sequence stratigraphic analysis of superimposed coal measure gas-bearing system in Daning-Jixian block,eastern margin of Ordos Basin,China

The identification of superimposed gas-bearing systems in coal measures is the basis for expediting the optimization of coal measure gas co-production.Through the analysis of drill cores and log data of Upper Carboniferous Benxi Formation to the member 8 of Middle Permian Lower Shihezi Formation in Daning-Jixian block,eastern margin of Ordos Basin,four distinct superimposed coal measure gas-bearing systems were identified,and their formation mechanism was discussed from the sequence stratigraphic perspective.Type Ⅰ system mainly contains multiple coal seams,shales and sandstone layers.Type Ⅱ system is dominated by multiple coal seams and shales.Type Ⅲ is characterized by multiple sandstone layers,and type Ⅳ system is dominated by limestones and mudstones.In general,the gas-bearing systems deposited in barrier-lagoon are type Ⅱ,those deposited in carbonate tidal flats are type IV,and those deposited in the delta front are types Ⅰ and Ⅲ.The marine mudstone,acting as a key layer near the maximum flooding surface,exhibits very low permeability,which is the main factor contributing to the formation of superimposed gas-bearing systems.The sedimentary environment plays a significant role in controlling the distribution of gas-bearing systems.Notably,the vertical gas-bearing systems in the south-western region,where delta front and lagoon facies overlap,are more complex than those in the north-eastern delta front facies.

Tertiary Sea Level Changes and Sequence Stratigraphic Framework in East China Sea Shelf Basin

The East China Sea shelf basin is a key area for setting up the sea level changes of Cenozoic in the West Pacific. Based upon the characteristics of seismic reflection, the analysis of sequence stratigraphy and depositional system, the high resolution chronostratigraphic framework has been set up by using the data of micropaleontologic biozone fossils. The relative sea level change curve has been set up by combining analysis of paleoecology, genetic facies, specific sedimentary structures and on lap recognized from the seismic profiles with study of geochemical characteristics. There are 4 2nd order basin cycles showing the long term sea level changes, and 22 3rd order cycles showing short term ones with relative changing ranges of 0-150 m. Transgression and regression showing long term sea level changes bear asymmetric feature, which indicates that the speed of transgression is faster than that of regression. There are a lot of differences when compared with Haq ’s curve. The sequence stratigraphic framework has also been set up and 3 tectonic sequences, 7 supersequences and 19 sequences have been subdivided for Tertiary in the East China Sea shelf basin. On the basis of detailed analysis of genetic facies and log facies, 9 sedimentary systems, 20 depositional assemblages and many genetic facies have also been recognized and investigated. Based on the studies mentioned above, the favorable source and reservoir facies of gas and petroleum are indicated.

Sedimentary architecture and distribution of intra-platform shoal in sequence framework of Permian Changxing Formation in central Sichuan Basin,SW China

Based on the comprehensive analysis of core, thin section, logging and seismic data, this study carried out the identification and comparison of Permian Changxing Formation sequences, clarified the typical sedimentary architectures of intra-platform shoal, investigated the vertical and horizontal development and distribution of intra-platform shoal in each sequence, and thus established the sedimentary evolution model of shoal body. The study results are reflected in four aspects.First, there are two complete third-order sequences(SQ1 and SQ2) in Changxing Formation in central Sichuan Basin. SQ1 is generally thick in the north and thin in the south, and SQ2 shows a thickness differentiation trend of “two thicknesses and three thinnesses”. Second, the Changxing Formation in central Sichuan Basin mainly develops intra-platform shoal, inter-shoal sea and intra-platform depression subfacies. In the vertical direction, the intra-platform shoal mainly presents two typical sedimentary sequences: stable superposed and high-frequency interbedded. Third, the stable superimposed sedimentary sequence is developed in the shoal belt at the edge of intra-platform depression, which is composed of two shoal-forming periods and located in the highstand systems tracts(HSTs) of SQ1 and SQ2. The high-frequency interbedded sedimentary sequence is developed in the southern shoal belt of intra-platform depression, which is composed of four shoal-forming periods and mainly located in the HST of SQ2. Fourth, during the SQ1 deposition, the intra-platform shoal was mainly developed at the edge of the intra-platform depression on the north side of the study area, and the inter-shoal sea subfacies was mainly developed on the south side. During the SQ2 deposition, the intra-platform shoal was widely developed in the area, forming two nearly parallel intra-platform shoal belts. The study results provide direction and ideas for exploration of Changxing Formation intra-platform shoal reservoirs in central Sichuan Basin.

Stratigraphic Sequence and Tectonic Evolution of Passive Continental Margin of Jinshajiang Belt in Northwestern Yunnan, China

The Jinshajiang belt, located between the Zhongzan and Qamdo massifs, preserves varied sediments representing different tectonic background. Those sediments outcrop in stratigraphic slices,not in continuous stratigrapky. The stratigraphic slices of the passive continental margin are investigated by geologic mapping in Tuediug-Xiaruo, Northwestern Yunnan Province, and each of these slices is researched in age and sedimeutary environment. The stratigraphic successions of the passive continental margin are reconstructed. On the basis or new sequence, the evolutional history of the passive continental margin is divided into four stages: rift basin (D,-C,), complex continental margin basin (P1 ), residual hasin (P2-T2) and synorogenic basin (T3).

Stratigraphic Sequences and Their Implication in a Sea Area of the Western Yellow Sea Near Qingdao Coast During the Late Quaternary

An analysis of seismic data obtained through a cable route survey starting from the Qingdao coast to offshore has determined nine seismic units since Late Pleistocene. Correlation of the seismic data with Borehole Hj2 confirms three eustatic events that occurred during the Late Quaternary and formed terrestrial units 2, 5 and 7. At the low sea level stage, paleo rivers highly developed, eroded previous strata, formed paleo valley, and left materials.

A Glance on the Mineral Deposits and Stratigraphic Sequential Variations and Structures in Different Sections of Indus Basin (Pakistan): New Titanosaurian Sauropod Dinosaurs from the Latest Maastrichtian Vitakri Formation of Pakistan

Indus basin hosts many significant mineral deposits like gypsum and cement raw materials, gemstones, iron, coal, marble, dimension and construction stones, petroleum and water resources, world class pink salt and other many minerals in different regions which need further exploitation and development. The construction of new water dams in different regions are vital (for availability of cheap electricity), because of available barren and fertile lands and wastage of water as flood. Further the installation of more cement industries in different regions of Indus Basin especially in middle Indus (Sulaiman Range where gypsum, clays and limestones can be available via belt) can increase export to receive more foreign exchange and make local cement cheap for the sustainable development of Pakistan. 31 stratigraphic sequential sections at different sections of Indus basins are presented to know the variation and local stratigraphy. Further here three new titanosaur taxa are being described. Saraikimasoom is based on snout;Gspsaurus, (Maojandino), Nicksaurus and Khanazeem are based on cranial, vertebral and appendicular elements;Balochisaurus, Marisaurus, Pakisaurus, and 3 new genera and species Imrankhanhero zilefatmi, Qaikshaheen masoomniazi and Ikqaumishan smqureshi based on vertebral and appendicular elements;and Sulaimanisaurus and Khetranisaurus based on only caudal vertebrae. Although Pakistani Titanosaurians seem to be proliferated found from one horizon of Vitakri Formation just below the K-Pg boundary they have a wide range of diagnostic features and key elements among titanosaurs which can be used for comparison and phylogenetic analyses with broad updated character data set of titanosaurs.

Sequence Stratigraphy of the Jurassic Coal Measures in Northwestern China

The sequence stratigraphy of the Jurassic coal measures of northwestern China has been studied based on data from outcrop and borehole sections. Because of the geological background and the diversity of basin types, such as isochronisms of coal seams and recognition of key sequence boundaries, it is rare to summarize and correlate sequence structure and framework. The types and recognition characteristics of the sequence boundaries of the Jurassic coal measures are revealed by comparing climatic characteristics, structural styles and the base level cycle. A total of five third-order sequences and 15 systems tracts have been subdivided and the sequence stratigraphic framework has been reconstructed confirming that the thick coals accumulated in the late stage of transgression system tracts of sequence I （SQ I） and sequence III （SQ III）. This idea is of important academic significance for instructing coal resources exploration, and enhancing geological effects of prospecting engineering. It is also of practical significance for guaranteeing construction of the large-scale coal production base in northwestern China, accelerating the westward development of the coal industry stratagem.

Sequence Stratigraphy of Paleozoic in North Tarim Basin

The Paleozoic sequence stratigraphic system of North Tarim basin is established for the first time in this paper. The sequence stratigraphic system is composed of different orders of sequences, which includes 96 sequences, 31 supersequences, 9 supersequence sets and 4 megasequences. The characteristics of some important sequence boundaries are discussed and their time ranges are suggested, thus enhancing the precision of stratigraphic correlation in North Tarim basin.

Depositional Sequences of Yitong Graben (Eastern China) and Its Response to Transform-Extensional Processes

The Yitong graben is located in the northeastern segment of the Tertiary rift system in East China. The graben is bounded by a steep dipping transform fault on the northwestern side and subparallel normal faults on the southeastern side, with very thick marginal fan complexes indicating syntectonic sedimentation. The graben is infilled with Tertiary sediments up to 6 000 m thick, in which a series of different scaled hiatuses and tectonic inversion events have been discerned during hydrocarbon exploration. According to regional and local conformities, the basin infill may be divided into three tectonic sequences, among which the major sequence TS2 is further subdivided into three sequence sets and fourteen subsequences. Based on the sequence stratigraphic framework, depositional system tracts which are characterized by marginal fan complexes on both sides of basin and deep or shallow lacustrine deposits in the central part are reconstructed. The subsidence curves show that the graben had undergone several rapid subsidence episodes, which is interpreted to have been caused by multiple stretching of the lithosphere. Integrative analysis of the depositional structural features shows that the regional tectonic stress system experienced a transformation from dextral transformational shear through thermal subsidence to sinistral compressional shear with a general extensional setting. Extension and wrenching dominated the graben evolution and affected the depositional style in different evolutionary stages, the spatial configuration of depositional system and its relationship with unconformities. The conclusions have been applied with some successes to studying the reservoir and hydrocarbon source rock distribution and lithologic stratigraphic traps in this basin.

Study on Carbonate Sequence Stratigraphy of Ordovician in Northern Ordos Basin

The formation of carbonates is different from that of siliciclastics. The controlling factors, such as the in-situ production of carbonates the transport, local variation in depositional processes and the way of dispersal are unique to carbonates systems, and have resulted in the formation of a wide variety of stratal patterns. The authors believe that all the factors influencing the formation of carbonates, such as the evolution of carbonate platform, transgression and regression, drowning and exposing of the platform, should be taken into consideration during the study of carbonate sequence stratigraphy.This paper attempts to summarize the study procedure in outcrop sequence stratigraphy and to describe the integrated identification of condensed section, first flooding surface and maximum flooding surface, so that the framework of high-resolution sequence stratigraphy can be constructed. During the Sandokan in early Ordovician, a carbonate-siliciclastic ramp was developed in northern Ordos, which changed into a carbonate rimmed shelf or a distally steepened ramp during the Zhuozishan and Kelimoli. It was the break in the Wulalike and Middle Ordovician,changing the sedimentary setting into an aulacogen According to the basin evolution, the authors have established some different idealized models for depositional sequences and systems tracts.

Geometric and Dynamical Characteristics of Sequences in Yitong Graben

Yitong graben belongs to the north segment of the Tanlu fault belt .It was infilled with Eogene, Neogene and Quaternary clastic deposits, each Of them represents a distinct tectonic sequence.Six types of systems association characteristics of distinct depositional systems and spatial disposition are identified in different evolutionary period of the graben.Sequence Stratigraphic framework of the graben is mainly controlled by structural framework,tectonic movement, sources supply, expanding and contracting cycle of lake, position of depositional center. The key factors are structural framework and tectonic movemeat.Through systematic analysis Of regional tectonic settings, it is recognized that Eogene tectonic sequence of Yitong graben was formed under tenso-shear regime. It includes four sequences indicating four tectonic events attributed to tectonic movement of marginal faults.Neogene tectonic sequence was formed under compresso-shear regime, which includes coarse clastic deposits with a thicknessof 0-500m.Pattern of in the Yitong graben indicates the asymmetrical subsisence of marginal faults along two sides and the complicated structural framework.

Genesis of sandstone-type uranium deposits along the northern margin of the Ordos Basin,China

Sandstone-type U mineral resources are among the important sources for nuclear energy.The U deposits in the Ordos Basin in China form part of the northern segment of the sandstone-hosted Central Asian Uranium MegaProvince.Two types of mineralizations are recognized in this basin:"phreatic permeable type"and"interlayer permeable type",both exhibiting features equivalent to roll-front subtypes.The"interlayer permeable type"is widely accepted as the dominant mineralization type for sandstone-type uranium deposits within large-scale basins,also designated as the"interlayer oxidation zone type",based on the horizontal color zoning model representing changing redox conditions.Here we synthesize data from several drill holes within the Ordos Basin,which suggest that major Mesozoic tectonic movements controlled the evolution of the sedimentary system in the basin.These tectonic movements contributed to the formation of three angular unconformities and four parallel unconformities as inferred from the stratigraphic relationships.In addition,other features such as vertical color zoning,paleo-channel controlled tabular or lentoid ore bodies(without roll-type)and a group interlayer horizontal zoning of altered minerals are also documented.Sequence stratigraphic analysis indicates that the Ordos Basin generally witnessed four cycles of water level variations during Mesozoic.During the variations,three high water level and three low water level events were recorded.Biological characteristics imply that the Ordos Basin went through multiple arid to humid climatic evolutions during Mesozoic.Combining the newly documented features with some novel concepts on the hydrodynamic mechanism for supergene ore-forming fluids,we propose a metallogenic model which invokes the importance of tectonic movements and water level fluctuations to explain the genesis of uranium deposits along the northern margin of the Ordos Basin.

Simulation of the Subsidence and Deposition Processes of the Foreland Basin in the Southwestern Margin of Ordos

Characteristics of deformation in the thrust belt and sequence stratigraphic framework in the foreland basin, structural features of the basin margin, and the episodic thrusting are studied in this paper by combining the eastern Qilian thrust belt and the Late Triassic foreland basin on the southwestern margin of Ordos. On this basis, a geological model and a mechanical model of coupling mechanism were established for the pair of thrust belt and foreland basin, and the subsidence and deposition process of the foreland basin were simulated on given parameters.

Mesozoic “Red Beds” and its Evolution in the Hefei Basin

The Hefei Basin is the largest basin in the North China landmass with complete and well-preserved Mesozoic and Cenozoic strata. In the basin there developed a suite of extremely thick ＂red beds＂ in the Mesozoic. Owing to complex evolution processes and a lack of paleontological traces, there have been controversies regarding the division and correlation of this suite of red beds. Based on results obtained in recent years in drilling, seismic and surface geological investigations and in consideration of relationships between seismic sequences and regional tectonic events, as well as evidence in paleontology, petrology and isotopic dating, this paper preliminarily puts forward the following ideas about the sequence stratigraphic framework of the continental ＂red beds＂ in the Hefei Basin. （1） The Zhougongshan Formation and the Yuantongshan Formation have similar lithologic, geophysical and paleontological characteristics, so we incorporate them into a single formation, called the Yuantongshan Formation, and the original Zhougongshan and Yuantongshan Formations are regarded as the upper and the lower parts of the newly defined Yuantongshan Formation. Its age is the Middle Jurassic; （2） the Zhuxiang Formation belongs to the Upper Jurassic Series and （3） the age of the Xiangdaopu Formation is the Lower Cretaceous. Furthermore, signatures of depositional evolution are analyzed in the paper based on features of seismic reflection, outcrops and drilling data. The Early and Middle Jurassic is characterized by a foreland basin, which is influenced mainly by uplift and longitudinal compression of the Dabieshan Mountains; the Lower Jurassic System has a relatively small depositional area; the Middle Jurassic strata are distributed extensively over the whole basin, marking the summit of basin development; a flexure basin is characteristic of the Late Jurassic, manifesting a joint effect of the Dabieshan and Zhangbaling Mountains with the former being more significant. In the Early Cretaceous, the Xiangdaopu Formation was distributed in the Daqiao depression, evidently affected by extension of the Tanlu fault; in the Late Cretaceous, the Hefei Basin was subjected to dismembering and the Zhangqiao Formation was distributed in the east-west direction along the downthrown side of the fault.

Carboniferous-Permian Stratigraphy and Sedimentary Environment of Southeastern Inner Mongolia,China:Constraints on Final Closure of the Paleo-Asian Ocean

In this paper we discuss the timing of final closure of the Paleo-Asian Ocean based on the field investigations of the Carboniferous-Permian stratigraphic sequences and sedimentary environments in southeastern Inner Mongolia combined with the geology of its neighboring areas. Studies show that during the Carboniferous-Permian in the eastern segment of the Tianshan-Hinggan Orogenic System, there was a giant ENE-NE-trending littoral-neritic to continental sedimentary basin, starting in the west from Ejinqi eastwards through southeastern Inner Mongolia into Jilin and Heilongjiang. The distribution of the Lower Carboniferous in the vast area is sparse. The Late Carboniferous or Permian volcanic-sedimentary rocks always unconformably overlie the Devonian or older units. The Upper Carboniferous-Middle Permian is dominated by llttoral-neritic deposits and the Upper Permian, by continental deposits. The Late Carboniferous-Permian has no trace of subduction-collision orogeny, implying the basin gradually disappeared by shrinking and shallowing. In addition, it is of interest to note that the Ondor Sum and Hegenshan ophiolitic melanges were formed in the pre-Late Silurian and pre-Late Devonian respectively, and the Solonker ophiolitic melange formed in the pre-Late Carboniferous. All the evidence indicates that the eastern segment of the Paleo-Asian Ocean had closed before the Late Carboniferous, and most likely before the latest Devonian （Famennian）.