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Natural fibrous gypsum is a kind of high-quality gypsum resources, whose high-value added utilization pathway is to be transformed to α -calcium sulfate hemihydrate (α -HH), a cementitious material that can react with water to form pastes with mechanical strength. In this work, α -HH was prepared from natural fibrous gypsum in KCl mediated glycerol-water solution under mild condition. KCl played a simultaneous function on regulating the phase-transition kinetics, morphology and comprehensive strength of α -HH. Addition of low concentration of KCl prominently retarded the nucleation and growth rate of α -HH and decreased its aspect ratio due to the formation of syngenite on the side faces. While further increase of KCl concentration accelerated the nucleation and growth rate and decreased the crystal sizes. In the presence of 0.04 M KCl, the prepared α -HH presented a hexagonal prism shape with a length / width of 257.69–579.71 μm / 13.13–36.61 μm, and its dry comprehensive strength had reached 38.1 MPa that was comparable to those prepared in commercial, chloride and nitrate system. Altogether, the foreign ion-free glycerol-water solution contributed to transforming natural fibrous gypsum to α -HH with high purity and high mechanical strength. • Transformation of natural fibrous gypsum to α -HH in glycerol-water solution. • Regulation of KCl on phase-transition kinetics, morphology and mechanical strength. • Hexagonal prism shape α -HH with high aspect ratio presents high mechanical strength. • α -HH paste with high mechanical strength has a compact microstructure. [ABSTRACT FROM AUTHOR]

The identification of formation fluid properties of igneous rock reservoirs plays a vital role in the igneous rock oil/gas exploration and development. Due to the complex lithology, low porosity, low permeability and strong heterogeneity of igneous rock reservoirs, conventional geophysical logging evaluation methods are not as accurate as sandstone reservoirs in response to different fluid properties of igneous rock reservoirs. It is difficult to identify the fluid type of the formation. In order to solve this problem, with the rapid development of array acoustic logging technology, this paper proposes a new method for analyzing the time–frequency characteristics of full wave train data based on the large amount of information contained in the array acoustic wave train, hoping to more accurately identify the fluid properties of igneous rock reservoirs. This paper introduces the time slice and frequency slice of Choi–Williams distribution with different IMF components obtained by EMD method and analyzes the characteristics of time slice and frequency slice of reservoirs with different fluid properties, in order to be used for identification of formation fluid types. The results show that the time slices and frequency slices of different IMF components have significantly different characteristics for different formation fluid properties of igneous rocks. This new method can provide geophysical and geological researchers with some new information to more accurately identify the properties of formation fluids. [ABSTRACT FROM AUTHOR]

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This study attempts to augment geology and potential hydrocarbon play system database not only in the Maamba Coalfield basin of southern Zambia but in other similar continental non-marine Karoo rift basins in the region as well. Geological analyses were conducted through extensive outcrops and exposures and subsurface boreholes. Six (6) major lithofacies (diamictites, conglomerates, sandstones, siltstones, coal and mudstones) represents Lower Karoo Group sequence. Four (4) mudstone core samples were prepared for thin section petrography. In addition, six (6) samples of sandstones obtained from outcrops, exposures and cores were impregnated with blue epoxy before thin sectioning in order to facilitate easy recognition of porosity. Quantification of framework grain composition and porosity was achieved by point counting a total of 300 points per thin section. The identification of diagenetic constituents and pore types was made possible by the use of scanning electron microscopy (SEM). Rock-Eval pyrolysis analyses utilised 35 core samples of mudstones and coal. According to results of the analyses, three (3) deposition settings which include; alluvial, fluvial-lacustrine and lacustrine setting are envisaged. . Fluvial-lacustrine deposits are host to mudstones and coal source rocks and sandstone reservoir rocks. Mudstones and coal source rocks gave the total organic carbon (TOC) that is well above the recommended thresholds of 0.5 wt % and 2.5 wt % of gas and oil generation respectively. The hydrogen index (HI) values are mostly below 200 mg HC/g TOC, indicating fair quantities of type III kerogen. The thermal maturity readings measured by temperature T max range from 440 to 485 °C in agreement with calculated vitrinite reflectance (Ro calc ) range of 0.76–1.57% indicating mature to post mature stages. This maturation is attributed to the burial temperatures and near-surface heat flows by faults. Production Index (PI) values are less than 0.1 suggesting some hydrocarbon expulsion possibly gases and gas condensates. Sandstones are moderate to poor sorted sublitharenites. Total porosity in sandstones range between 0 and 6.3%, averaging 2.5%, and is mainly secondary porosity resulting from dissolution of labile minerals and fracture. Deposition and diagenetic related controls influenced much of the reservoir quality in sandstones. Lacustrine mudstones are the potential seal rocks. The major Structural traps are faults (e.g. normal and reverse faults) and the stratigraphic traps are sandstones. In this study, our area of focus is in the north and central part of Maamba Coalfield Basin where coal mining and exploration activities are currently taking place. The southernmost part of the basin is under developed such that the hydrocarbon play system potential is still unknown. However, recent coal exploration drilling has revealed the presence of source rocks at depth overlain by extensive overburden seal rocks. Based on the play concept analysis, it is possible to find more encouraging results from this area. [ABSTRACT FROM AUTHOR]

The Mesozoic rift basins of northeast China are characterized by a significant proportion of basalt due to the progressive emplacement of basalt lava flows. The objective of this study was to construct vesicle distribution models of the basalt lava flow units, including conceptual geological models and thickness models, to understand the architecture of the basalt and the gas reservoir distribution. The conceptual geological models were constructed based on the characteristics of outcropping basalt lava flows, with supplemental seismic data used to extrapolate the lateral extents of large-scale basalt lava flows. The thickness models were constructed using data on the thicknesses of basalt lava flow units and vesicle zones. These data were obtained from 27 units in outcrop and 204 units interpreted from well logs in the basin. The conceptual geological models revealed that the shapes of the basalt lava flow units change from braided to tabular with increasing thickness and that their inner structures can be divided into three vesicle zones: the top vesicle zone, the massive core zone, and the base vesicle zone. The thickness models revealed that trends in the thickness of the top vesicle zone relative to the thickness of the basalt lava flow unit can be expressed using a piecewise function that can be separated into a linear function and a logarithmic function. Similarly, trends in the thickness of the massive core zone and the base vesicle zone relative to the basalt lava flow unit thickness can be expressed by a piecewise linear function. Vesicle distribution models provide an effective means of determining the proportion and distribution of vesicle zones in basalt with limited borehole data. We also constructed a reservoir model based on our vesicle distribution models, and this model revealed that suitable petroleum reservoirs are primarily located in the thinner braided lava flows. [ABSTRACT FROM AUTHOR]

There are numerous controversies surrounding the tectonic properties and evolution of the Proto‐South China Sea (PSCS). By combining data from previously published works with our geological and paleontological observations of the South China Sea (SCS), we propose that the PSCS should be analyzed within two separate contexts: its paleogeographic location and the history of its oceanic crust. With respect to its paleogeographic location, the tectonic properties of the PSCS vary widely from the Triassic to the mid‐Late Cretaceous. In the Triassic, the Paleo‐Tethys and the Paleo‐Pacific Oceans were the major causes of tectonic changes in the SCS, while the PCSC may have been a remnant sea residing upon Tethys or Paleo‐Pacific oceanic crust. In the Jurassic, the Meso‐Tethys and the Paleo‐Pacific oceans joined, creating a PSCS back‐arc basin consisting of Meso‐Tethys and/or Paleo‐Pacific oceanic crust. From the Early Cretaceous to the mid‐Late Cretaceous, the Paleo‐Pacific Ocean was the main tectonic body affecting the SCS; the PSCS may have been a marginal sea or a back‐arc basin with Paleo‐Pacific oceanic crust. With respect to its oceanic crust, due to the subduction and retreat of the Paleo‐Pacific plate in Southeast Asia at the end of the Late Cretaceous, the SCS probably produced new oceanic crust, which allowed the PSCS to formally emerge. At this time, the PSCS was most likely a combination of a new marginal sea and a remnant sea; its oceanic crust, which eventually subducted and became extinct, consisted of both new oceanic crust and remnant oceanic crust from the Paleo‐Pacific Ocean. In the present day, the remnant PSCS oceanic crust is located in the southwestern Nansha Trough. [ABSTRACT FROM AUTHOR]

• Triassic paleobiogeography of PSCS was constrained by both Pacific and Tethys oceans. • Triassic PSCS subjected to tectonic overprints of Pacific and Tethyan tectonic regimes. • Early–Middle Jurassic paleobiogeography of PSCS was controlled by the Pacific Ocean. • Late Jurassic–Cretaceous PSCS was in a semi-closed environment. • Jurassic–Cretaceous PSCS was part of the Paleo-Pacific slab. The Proto-South China Sea (PSCS) represents the lithosphere that formerly occupied the region southeast of South China where the present-day South China Sea is located. The subduction and demise of the PSCS have attracted wide attention, whereas the pre-subduction history (particular the Mesozoic) of the region remains relatively neglected. In this paper, the radiolarian paleobiogeography of the region is analyzed to identify the paleobiogeographic affinity and paleo-connectivity of the PSCS with the Pacific and Tethys oceans during the Mesozoic. Then the continent–ocean configuration and tectonic evolution of the PSCS and adjacent areas are discussed through the integration of paleobiogeographical results and associated paleomagnetic, stratigraphic, and petrologic data. The main conclusions are as follows: (1) During the Triassic, the PSCS was situated in the transition zone between the Pacific and Tethys oceans, and its paleobiogeography was influenced by both oceans. The PSCS was characterized by complex tectonic overprinting by the Pacific and Tethyan tectonic regimes. (2) In the Early–Middle Jurassic, the PSCS was well connected to the Pacific Ocean but poorly connected to the Tethys Ocean, consistent with the paleobiogeography of the PSCS being mainly constrained by the Pacific Ocean. The PSCS was part of the Paleo-Pacific slab. (3) During the Late Jurassic–Cretaceous, the PSCS was in a semi-closed environment. The Late Jurassic–early Late Cretaceous PSCS was part of a west-facing Andean-type subduction zone, and the late Late Cretaceous PSCS was situated in an extensional tectonic setting. [ABSTRACT FROM AUTHOR]

The Late Jurassic-Early Cretaceous Wandashan accretionary complex (AC) in NE China is a key region for constraining the subduction and accretion of the Palaeo-Pacific Ocean; however, the protoliths and structure of the region remain poorly understood, resulting in debates regarding crustal growth mechanisms and subduction-related accretionary processes in Northeast China. In this contribution, we integrate detailed field observations, ocean plate stratigraphy (OPS) reconstruction, and associated geological data to determine the structure and tectonic evolution of the Wandashan AC. The Wandashan AC formed through the progressive incorporation of OPS units along an oceanic trench. The observed OPS comprises, in ascending order, Permian basalt and limestone, Middle Triassic-Early Jurassic chert, Middle Jurassic siliceous shale and mudstone, and Late Jurassic-Early Cretaceous turbidite. Numerous NNE-SSW-striking thrust faults have segmented the OPS into a series of bedding-parallel tectonic slices that were successively thrust over the Jiamusi massif along a basal thrust (the Yuejinshan Fault), producing a large-scale imbricate thrust system. The Wandashan AC underwent oceanward accretion via multiple deformational processes. The OPS units were detached and rearranged along or within a decollement through offscraping, underplating, thrusting, and duplexing. The units were then emplaced over the Jiamusi massif along the basal thrust. The timing of accretion and thrusting is constrained to the latest Middle Jurassic to earliest Early Cretaceous (ca. 167-131 Ma). Reconstructed accretion-related structural lines within the Wandashan AC trend dominantly NE-SW, close to the direction of Jurassic extension at the eastern Asian continental margin. Large-scale left-lateral strike-slip movement on the Dunmi Fault during the late Early Cretaceous resulted in the folding of structural lines within the Wandashan AC, producing their present-day westward-convex orientation. [ABSTRACT FROM AUTHOR]

The Kungurian period in the late Palaeozoic was characterized by a climatic transition from icehouse to greenhouse conditions, during which organisms flourished. Thick carbonate rocks developed in shallow water in most of the low-latitude palaeogeographic areas of the globe in this period. The sedimentary environments have long been considered steady and unidirectional. However, studying the Xuyong section in South China and comparing it with other regions may change this view. In this study, we obtained the lithological and geochemical data for slope facies carbonate rocks, including eight sedimentary microfacies from MF1 to MF8. The results showed transgressions in the Xuyong section characterized by an increase in palaeosalinity, a decrease in seawater temperature, and an increase in reduction. By comparing 13 sections from the same low palaeolatitude, we found that there may be four changes in the carbon isotope and strontium isotope chemical strata. These changes might provide support for a potential global palaeoenvironment event, the Kungurian Carbon Isotopic Excursion. Moreover, although the geochemical characteristics in different regions include good comparability, nonetheless seawater circulation and the palaeoclimate were found to be the main factors influencing the carbon cycle after excluding the influence of tectonic factors and volcanic eruptions. Additionally, we inferred that although thick carbonate rocks were produced in different low-latitude oceans, these carbonate rocks did not necessarily form in the same environment. During periods of tectonic stability, the influence of palaeoclimatic conditions on sedimentary environments cannot be ignored. [ABSTRACT FROM AUTHOR]

Acidic lava flows comprise a large proportion of the total volcanic succession in the rift basins of northeast China. The objective of this study was to explore the vesicle distribution in the acidic lava flows in those basins. Two representative areas with acidic lava flow outcrops in NE China were selected for study. These lava flows share similar magma sources and chemistries. The types and inner structures of the acidic lava flows were determined in detail by measuring the shape of the flows (thickness and lateral extent) and the vertical sequences in the outcrops and shallow coring well Y1D1 in the two outcrop areas. Furthermore, the interpretation of deep borehole data and 3D seismic data from the Changling Graben of the Songliao Basin provided additional thickness and geometry data as a robust complement to the outcrop data. This study revealed that the shapes of the acidic lava flows transition from dome to tabular to braided with decreasing size. Furthermore, the vertical sequences can be classified into three zones: the upper vesicle zone, the massive core zone and the basal zone. The borehole thickness data indicate a trend in the maximum proportions occupied by the upper vesicle zone: thick flows have a relatively low proportion occupied by upper vesicle zones, whereas thin flows display a wide range in the proportion represented by upper vesicle zones. Therefore, braided acidic lava flows are more likely to have a high proportion of upper vesicle zones. Upper vesicle zones usually have high porosity and permeability and represent the primary effective gas reservoir system. The greatest lateral extents of gas reservoirs are usually in the tabular acidic lava flows, but the largest proportions occupied by gas reservoirs are usually in stacked braided lava flows. This study can help us to better understand the distribution of volcanic petroleum reservoirs in acidic lava successions where hydrocarbons are encountered but borehole data are limited. Furthermore, this study is useful for interpreting acidic lava flows in logs and seismic data from basins. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Highlights from the article: The International Continental Scientific Drilling Project of the Songliao Basin includes the SK-1 boreholes (the SK-1 south borehole and the SK-1 north borehole) and SK-2 boreholes (the SK-2 east borehole and the SK-2 west borehole). Of these nine zircon samples, the isotopic ages of seven zircons showed the weighted average SP 206 sp Pb/ SP 238 sp U age of 242.4 ± 2.1 Ma (MSWD = 0.06, n = 7). In the 6,373.9 m interval, eighteen zircon samples from the andesite displayed concordant ages, which showed a weighted average of SP 206 sp Pb/ SP 238 sp U age 242.6 ± 1.5 Ma (MSWD = 1.02, n = 18) (Fig. 1d).

Research on the distribution of mantle CO2 should involve comprehensive analysis from CO2 source to accumulation. The crust‐mantle pathway system is the key controlling factor of the distribution of mantle CO2, but has received little attention. The pathway system and controlling factors of CO2 distribution in the Bohai Sea are analyzed using data on fault styles and information on the mantle and lithosphere. The relation between volcanic rocks and the distribution of mantle CO2 is reassessed using age data for CO2 accumulations. The distribution of mantle CO2 is controlled by uplift of the asthenosphere and upper mantle, magma conduits in the mantle and fault systems in the crust. Uplifted regions of the asthenosphere are accumulation areas for CO2. The area with uplift of the Moho exhibits accumulation of mantle CO2 at depth. CO2 was mainly derived from vertical migration through the upper mantle and lower crust. The fault style in the upper crust controls the distance of horizontal migration and the locations of CO2 concentrations. The distribution of mantle CO2 and volcanic rocks are not the same, but both probably followed the same pathways sometimes. Mantle CO2 in the Bohai Sea is concentrated in the Bozhong sag and the surrounding area, particularly in a trap that formed before 5.1 Ma and is connected to crustal faults (the Bozhang faults) and lithospheric faults (the Tanlu faults). [ABSTRACT FROM AUTHOR]

The ecogroup classification based on the growth-form of plants (Eco-Plant model) is widely used for extant, Cenozoic, Mesozoic, and Paleozoic paleoenvironmental reconstructions. However, for most Mesozoic dispersed sporomorphs, the application of the Eco-Plant model is limited because either their assignment to a specific ecogroup remains uncertain or the botanical affinities to plant taxa are unclear. By comparing the unique outline and structure/sculpture of the wall of dispersed sporomorph to the sporomorph wall of modern plants and fossil plants, 861 dispersed Mesozoic sporomorph genera of Bryophytes, Pteridophytes, and Gymnosperms are reviewed. Finally, 474 of them can be linked to their closest parent plants and Eco-Plant model at family or order level. Based on the demands of the parent plants to different humidity conditions, the Eco-Plant model separates between hydrophytes, hygrophytes, mesophytes, xerophytes, and euryphytes. Additionally, due to different temperature demands a separation in megathermic, mesothermic, microthermic, and eurythermic plants is possible. In the Mesozoic, both spore-producing and pollen-producing plants are adapted to different kinds of humidity. The concept to use the spore/pollen ratio to reflect the hygrophytes/xerophytes ratio is therefore questionable. The presented ecogroups for dispersed Mesozoic sporomorphs now allow identifying at least relative plant, paleoenvironmental and paleoclimate changes in Mesozoic sedimentary records. • Linking Mesozoic dispersed sporomorphs to their possible parent plants. • Linking Mesozoic dispersed sporomorphs to humidity and temperature. • Providing a useful method to use Mesozoic dispersed sporomorphs for paleoenvironmental reconstruction. [ABSTRACT FROM AUTHOR]

While Archean buried hill fractured reservoirs have been found for the first time in the BZ19‐6 Block of the Bozhong Sag in the Bohai Bay Basin, the mechanisms driving their creation and evolution are not well known for low degree of exploration. Using core data, image logs, and our knowledge of the regional geology, we characterized the features and explored the formation mechanisms of these fractures. Our core samples captured two types of fractures: high‐angle shear fractures and low‐ to moderate‐angle tensile fractures. Based on the cross‐cutting relationships, four distinct sets of fractures formed at different stages and related to different tectonic events. The first fracture set (Set I) is high‐angle shear fractures having an E‐W orientation, partially filled by calcite, and was formed by transpressive processes in the Early Yanshanian. The second fracture set (Set II) is characterized by moderate angles, partially filled by asphalt and calcite with variable orientations and a more mesh‐like appearance, formed in an extensional environment in the middle Yanshanian. During transpressive activities in the Late Yanshanian, the high‐angle shear fractures of the third fracture set (Set III) formed with NW‐SE orientations and partially filled by asphalt. The fourth fracture set (Set IV), which occurred in the Early Himalayan, involves high‐angle shear fractures that is oriented in the NE‐SW direction and only part of them are filled by clay minerals. Macroscopic fracture features, orientations, and distribution patterns can significantly alter the nature of a reservoir; the fractures in Set I (E‐W‐oriented) and III (NW‐SE‐oriented) are typically the widest (excluded fills), and they tend to have the greatest impact on the overall reservoir permeability. [ABSTRACT FROM AUTHOR]

Based on the volume magnetic susceptibility and specific gravity measurements and mineral and lithologic identification results for 540 samples, the rock type, density, and magnetic susceptibility of rocks from northern Borneo were analyzed, and the applicability of gravity and magnetic data to the lithologic identification of the Mesozoic strata in the southern South China Sea was assessed accordingly. The results show that there are 3 types and 25 subtypes of rocks in northern Borneo, mainly intermediate‐mafic igneous rocks and exogenous clastic sedimentary rocks, with small amounts of endogenous sedimentary rocks, felsic igneous rocks, and metamorphic rocks. The rocks that are very strongly–strongly magnetic and have high–medium densities are mostly igneous rocks, tuffaceous sandstones, and their metamorphic equivalents. The rocks that are weakly magnetic‐non‐magnetic and have medium–very low densities are mostly conglomerates, sandstones, siltstones, mudstones, and coal. The rocks that are weakly magnetic‐diamagnetic and have high‐medium densities are mostly limestones and siliceous rocks. The Cenozoic rocks are characterized by low densities and medium susceptibilities; the Mesozoic rocks are characterized by medium densities and medium–high susceptibilities; and the pre‐Mesozoic rocks are characterized by high densities and low magnetism. Based on these results and the distribution characteristics of the various rock types, it was found that the pre‐Mesozoic rocks produce weak regional gravity anomalies; the Mesozoic sedimentary rocks produce negative regional gravity anomalies; whereas the Mesozoic igneous rocks produce positive regional gravity anomalies; and the Cenozoic igneous rocks produce positive regional gravity anomalies. The regional high magnetic anomalies in the southern part of the South China Sea originate from the Mesozoic mafic igneous rocks and their metamorphic equivalents; and the regional medium magnetic anomalies may be produced by the felsic igneous rocks and their metamorphic equivalents. Accordingly, the identification of the Mesozoic lithology in the southern South China Sea shows that the Mesozoic sedimentary rocks are distributed over a large area of the southern South China Sea. Thus, it is concluded that the Mesozoic strata in this area have the potential for oil and gas exploration. [ABSTRACT FROM AUTHOR]

A gas field consisting of volcanic reservoir rocks was discovered in the block‐T units of the Xihu Sag, East China Sea Basin. The lithology of the volcanic rocks is dominated by tuff and reworked tuff. The lithofacies are dominated by base surge deposits of explosive facies. As the architecture model of volcanic facies is still uncertain, it has restricted the exploration and development of mineral resources in this area. Using core and cuttings data, the lithology, lithofacies, geochemistry as well as grain size characteristics of volcanic rocks were analyzed. Based on these analyses, the volcanic rocks in the well section are divided into three eruptive stages. The transport direction of each volcanic eruption is analyzed using crystal fragment size analysis. The facies architecture of the block‐T units was established based on the reconstruction results of paleo‐geomorphology. The results show that the drilling reveals proximal facies (PF) and distal facies (DF) of the volcanic edifices. However, the crater‐near crater facies (CNCF) are not revealed. Compared with the reservoirs of the Songliao Basin, it is shown that the volcanic rocks in the Xihu Sag have good exploration potential; a favorable target area is the CNCF near the contemporaneous fault. [ABSTRACT FROM AUTHOR]

Highlights • B isotope data implied the formation of Changbaishan geothermal system is related to multiple vapor-liquid separation process. • The chemistry of springs is mainly controlled by the magmatic volatile input other than fluid-rock interaction. • New formation magma further encourages the phase segregation process. Abstract The goal of this study is to analyze fluid geochemistry, boron isotope and gas data to reassess the formation and evolution processes of the Changbaishan volcanic geothermal system (Jilin, China). Due to the presence of hot fumaroles (with temperatures of higher than 100 °C) and sinters, we believe that phase separation is occurring underground, which is also indicated by the characteristics of the B and gas data. Based on their hydrochemical data and B/Cl ratios, the thermal water samples in this area can be divided into three groups: 1) group 1 is steam-heated/condensate water (group 1-1: JJ, JLQ; group 1-2: SBDG, XRQ); 2) group 2 is karst water (CR3 and LSD); and 3) group 3 is residual water (CR1 and CR2). The preliminary discrimination of samples using B and gas data implies that group 1-1 around the crater is controlled by a second phase separation process, which is induced by the input of hot magmatic material; group 1-2 in the basin area is controlled by the transformation of clay minerals, and the XRQ water sample shows contamination by sewage; group 2 represents karst water that has leached metamorphic rock and been directly heated by the input of hot magmatic volatiles; and group 3 is the result of one seawater phase separation process. The mixing and fluid-rock interaction models based on the mass balance of boron concentration and isotope imply that the phase separation and input of magmatic volatiles are more important than fluid-rock interactions in the formation of the Changbaishan geothermal system, and the first phase separation process in the deep carbonate reservoir occurred in a late stage, with approximately 75%–87.5% of water becoming vapor. Additionally, the Rayleigh distillation of B isotope implies that new magma is being generated below this area, with the low B concentrations and high boron isotopic values of its gases implying that the mixed component may be derived from the subducted Pacific plate (e.g., marine sediment). The addition of "excess heat" due to the continued subduction of the Pacific plate has further encouraged the phase separation process, and the subduction process has also accelerated the transition of the hydrothermal system into a non-hydrothermal system. [ABSTRACT FROM AUTHOR]

We discuss the types, capacity, formation mechanisms, and main controlling factors of oil and gas reservoir spaces in Early Cretaceous acidic volcanic rocks of the Hailar Basin, NE China, where asphalt-bearing volcanic rocks are exposed at the surface. We have made systematic observations and analyses on macroscopic (outcrop) and microscopic (optical microscope, SEM, and fluorescence analyzer) scales. Acidic volcanic reservoirs contain reservoir spaces comprising primary and secondary porosity, which are dependent on primary and secondary processes during their formation. Primary porosity typically accounts for a large contribution to enhanced reservoir quality. More importantly, it is a prerequisite for migration, alteration, and filling by inorganic fluids and petroleum, which provides a foundation for the development of secondary porosity. The development of secondary porosity, especially alteration-related pores, can significantly modify the petrophysical characteristics of a rock. In addition to the processes of porosity formation, the quality of volcanic reservoirs is influenced by factors such as lithology, lithofacies, and tectonism. Lithological differences result in variations in the type and intensity of pore development. Pyromeride and glassy lava commonly exhibit high reservoir capacities. The porosity of different lithofacies typically follows the order of conduit facies > extrusive facies > effusive facies > explosive facies. Tectonism is necessary for the formation of reservoir spaces and for the migration, permeation, and accumulation of oil and gas. Reservoir quality is often positively correlated with the size and density of tectonic fractures. [ABSTRACT FROM AUTHOR]

The Cenozoic volcanostratigraphy in the Changbaishan area had complex building processes. Twenty-two eruption periods have been determined from the Wangtian'e, Touxi, and Changbaishan volcanoes. The complex volcanostratigraphy of the Changbaishan area can be divided into four types of filling patterns from bottom to top. They are lava flows filling in valleys (LFFV), lava flows filling in platform (LFFP), lava flows formed the cone (LFFC), and pyroclastic Flow filling in crater or valleys (PFFC/V). LFFV has been divided into four layers and terminates as a lateral overlap. The topography of LFFV, which is controlled by the landform, is lens shaped with a wide flat top and narrow bottom. LFFP has been divided into three layers and terminates as a lateral downlap. The topography of LFFP is sheet and tabular shaped with a narrow top and wide bottom. It has large width to thickness ratio. It was built by multiple eruptive centers distributed along the fissure. The topography of LFFC, which is located above the LFFP, has a hummocky shape with a narrow sloping top and a wide flat bottom. It terminates as a later downlap or backstepping. It has large width to thickness ratio. It was built by a single eruptive center. The topography of PFFC/V, which located above the LFFC, LFFP, or valley, has the shape of fan and terminates as a lateral downlap or overlap. It has a small width to thickness ratio and was built by a single eruptive center. The filling pattern is controlled by temperature, SiO2 content, volatile content, magma volume, and the paleolandform. In the short term, the eruptive production of the Changbaishan area is comenditic ash or pumice of a Plinian type eruption. The eruptive volume in future should be smaller than that of the Baguamiao period, and the filling pattern should be PFFC/V, which may cause huge damage to adjacent areas. [ABSTRACT FROM AUTHOR]

Today, NE China is highly affected by cold and dry winter monsoon winds, causing long and severe winters with monthly mean temperatures below − 10 °C. Yet, the Neogene paleoclimatic history of this region is not well understood due to the lack of precisely dated paleontological localities. Herein, we present several Ar–Ar basalt ages round a plant-bearing diatomite sequence of Badaogou, Changbai Mountains (Jilin Province; NE China — border to N-Korea), which allow us to revise its age from Miocene to ~ 2.5 Ma. A paleoenvironmental reconstruction based on fossil leaves, pollen and diatoms suggests deciduous forests rich in Acer , Quercus , Tilia , Ulmus and Zelkova mixed with conifers such as Tsuga , Picea and Abies within an already established mountain region close by. These forests were growing around a nutrient rich freshwater system with a pH > 7 in a presumably deep basin indicated by the strong dominance of planktonic diatoms Stephanodiscus minutulus and Pliocaenicus changbaiensis . The presence of tree taxa known from southern China today, such as Sassafras , Nyssa , Liquidambar , Podocarpus and Cedrus , leads to significantly warmer temperature estimates by the Coexistence Approach (mean annual temperature 11.5–15.7 °C, coldest month mean temperature − 0.3–9.6 °C, warmest month mean temperature 23.0–27.8 °C). Rainfall values aren't as precise, but suggest a mean annual precipitation of 843–1577 mm with monthly extremes of 109–220 mm (wettest), 17–41 mm (driest) and 73–175 mm (warmest). Although records in Eastern and Northern Asia as well as Central China report a cooling and drying after the onset of the Northern Hemisphere glaciation, the paleovegetation in NE China was not yet or hardly affected by the intensification of the winter monsoon. This emphasizes the importance of accurately dated records to improve large-scale paleoclimatic reconstruction as well as our understanding of the complexity of climate change. [ABSTRACT FROM AUTHOR]

Abstract: Cretaceous climate data of the long-lived Cretaceous Songliao Basin (SB) in eastern Asia is correlated and compared with the Western Interior Seaway (WIS) on the northern American plate, in order to understand better the dynamics of the Earth's past ‘greenhouse’ climates. Nearly continuous Late Cretaceous terrestrial deposition in the Songliao Basin is represented by two cores totaling 2431m in length. The Turonian–Maastrichtian age of the section is based on integrated stratigraphy, and is comparable in age with Upper Cretaceous strata in the WIS. Being consistent with global trends, the dynamic Late Cretaceous climates of both the SB and WIS gradually cooled from the warmest Albian–Cenomanian time to the end of the Maastrichtian with several intervening warm periods as did the global climate. However regional differences existed, the Songliao Basin climate was humid to semi-humid, warm temperate–subtropical and the Western Interior Seaway was in the humid, warm temperate zone and experienced only moderate climatic changes. The shifts of oxygen isotope data in the Songliao Basin were frequent and abrupt, whereas WIS records more gradual change affected mainly by fresh-water runoff mixing with southern Tethyan and northern Arctic waters. Sedimentary cycles of eccentricity, obliquity and precession bands are recorded in both the SB and WIS basins. The sedimentary cycles in the WIS and SB are interpreted to be related to variations of the wet/dry runoff cycles, which indicate that orbital forcing played an important role in global climate change in Late Cretaceous. The most favorable condition for organic carbon burial in both the SB and WIS basin was bottom water anoxia regardless of the cause of the anoxia. But the organic carbon burial rate was usually much higher in the Songliao Lake than in the WI epeiric sea suggesting that giant lakes may serve as important sinks of atmospheric CO2. In both basins organic-rich deposits formed during a rise in water level and incursion of saline waters. The integration of paleoclimate data from Cretaceous marine deposits and terrestrial sedimentary record will promote our understanding of the Cretaceous ‘greenhouse’ climate change and may provide insights for a future greenhouse world. [Copyright &y& Elsevier]

Abstract: The Songliao Basin is the largest Cretaceous oil and gas-producing lacustrine basin in China, with its greatest aerial extent in the middle Cretaceous. A coring program (SK1) has to date yielded 2485.89m of continuous core (96.46% recovery) and provides significant material for Cretaceous research. The sequence of the core consists mainly of lacustrine sandstone, dark grey mudstone, shale and oil-shale. The Upper Cretaceous stratigraphic section has been subdivided into the Quantou, Qingshankou, Yaojia, Nenjiang, Sifangtai and Mingshui formations in ascending order. Late Cretaceous microfossils are diverse and abundant. A detailed biostratigraphic study has subdivided the sequence into high precision biozones: 21 ostracode assemblages, 10 phytoplankton assemblages, 7 palynological zones and 4 charophyta assemblages, respectively. In addition, marine foraminifera were first discovered from the basin. Three 206Pb/238U ages and one 40Ar/39Ar age were analysed. Ten local magnetozones have been recognised in the SK1 (North), and two magnetozones have been indicated in the SK1 (South). Based on biostratigraphy, high-resolution magnetostratigraphy and SIMS U–Pb zircon analyses, the SK1 stratigraphy is correlated with Upper Cretaceous stages in the International Geologic Time Scale. The upper part of the Quantou Formation is the lower Turonian; the Qingshankou Formation is the upper Turonian–lower Coniacian; the Yaojia Formation is from the upper Coniacian to middle Santonian; the Nenjiang Formation is the upper Santonian to middle Campanian; the Sifangtai Formation is limited to the upper Campanian; and the Mingshui Formation is the uppermost Campanian to Maastrichtian. It is likely that the upper part of the Mingshui Formation belongs to the Paleocene, and the K/Pg boundary is within the Member 2 of the Mingshui Formation around the depth of 328m by new micropalaeontologic and magnetostratigraphic data. [Copyright &y& Elsevier]

Abstract: As a paradigm of greenhouse climate in Earth's history, the Cretaceous provides significant rock records of global climate changes under conditions of greenhouse climate. The Songliao Basin, among the longest duration (85–90m.y.) of continental sedimentary basins, provides an excellent opportunity to recover a nearly complete Cretaceous terrestrial sedimentary record. Extensive lake deposits, ten-kilometers deep and covering an area of 260,000km2 of the Songliao Basin, provide unique, detailed records that can be tied to the global stratigraphic time scale, thereby improving our understanding of the continental paleoclimate and ecological system. The two coreholes at SKIs and SKIn sites were drilled into this basin and completed with a total length of 2485.89m of recovered core that spanned the complete middle-to-Upper Cretaceous strata in the basin. The unique geological setting of long-term continuous subsidence within the largest Cretaceous landmass in the world — makes the Cretaceous Songliao Basin of northeastern China an ideal place to study Cretaceous climate change on the continent. This paper reviews the literature on the paleogeography and paleoclimate of the northern East Asia and the Songliao Basin during the Cretaceous. Based on the climatologically sensitive deposits, oxygen isotope studies, and paleontology, the climate during the Cretaceous in the Songliao Basin was temperate and humid with relatively abundant rainfall. During the period, significant changes – four cooling, three warming, and three semiarid events – are generally consistent with the oxygen isotope data from East Asia, and the four cooling events, in Berriasian–Valanginian, Aptian–Albian, early Santonian, and Campanian–Maastrichtian, may be related to potential glaciations in Cretaceous. [Copyright &y& Elsevier]

Terrestrial deposits of the Triassic-Jurassic transition are well developed in the Junggar Basin, located in the Haojiagou Valley of Urumqi, Xinjiang Uygur Autonomous Region of Northwest China. This paper describes the palynology of a 10 m thick lignite bed from the Upper Triassic Haojiagou Formation (Rhaetian) with the aim of reconstructing the palaeovegetation and palaeoenvironment of a peat-forming wetland near the Triassic-Jurassic boundary. The palynoflora contains both Eurasian and Gondwanan elements, and is dominated by the spores and pollen of Bennettitales, Corystospermales, Ginkgoales, and Gleicheniales. At the Triassic/Jurassic boundary (Hettangian), the palynoflora significantly changes as Cyatheales spores become the dominant elements. We analyze assemblages in terms of an Eco-Plant model, which assigns the parent plants of the palynomorphs into five groups based on humidity and four groups based on temperature, and uses multivariate statistical analyses to infer palaeoclimate and palaeoenvironmental conditions. Results suggest that the palaeoclimate of the Rhaetian was generally wet and subtropical with short seasonal drought periods. Our analysis shows that an Eco-Plant model may be a useful tool to reveal past vegetation patterns and climate changes, applicable to other Mesozoic assemblages. • Palynomorph study based on scanning electron microscope and light microscope. • Using Eco-Plant model to reconstruct Mesozoic humidity and temperature. • Palaeoenvironmental reconstruction near the Triassic-Jurassic boundary. • High-resolution Mesozoic palynomorph study • The Upper Triassic terrestrial Haojiagou Formation. [ABSTRACT FROM AUTHOR]

In the Cretaceous Songliao Basin, northeastern China, boreholes have recovered detailed geologic data from sub-basins that developed during the early rifting of the basin. Among these, the Lower Cretaceous Shahezi Formation (K 1 s) in the Songshen 4 (SS4) Well is represented by an 836-m-thick succession of fluvial-alluvial deposits, with coals distributed throughout the upper part of the formation. Gamma-ray (GR) logging data are quantitatively related to grain size-defined litho-facies that recur throughout the succession, with high GR values in mudstones and low GR values in sandstones. Cyclostratigraphic analysis of the GR log reveals depositional cycling at frequencies that are consistent with those of the Earth's astronomical parameters. The results also indicate that occurrence of coal beds occur every ~100 kyr, when development of vegetation at the depositional site was promoted by humid climate. We propose a model of astronomically forced hydroclimate change to explain the cycling of depositional environments between fluvial and alluvial conditions. The model describes a principally fluvial environment that episodically experienced, at one extreme, advancing alluvial conditions involving a drop in base level, lake recession and increased aridity (conglomerates and coarse sands), and at the other extreme, an advancing lakeshore with a rise in base level and increased humidity (fine sands, silts, muds and coal). A floating astronomical time scale was established by calibrating long orbital eccentricity (405-kyr) cycles interpreted along the GR series. The results indicate that the duration of the K 1 s is 11.14 Myr (27.5405-kyr long orbital eccentricity cycles), corresponding to an average sedimentation rate of 6.55 cm/kyr. The recognition of astronomical forcing in this early Cretaceous fluvial-alluvial-dominated depositional setting offers a new framework for interpreting the sedimentary cyclicity and dynamics of early rift basins and for developing time scales. • A cyclostratigraphy research is conducted on the Lower Cretaceous Shahezi Formation in Songliao Basin. • Cyclic alluvial-fluvial synrift deposition is recorded in the Shahezi Formation. • Gamma-ray logging data are linked to nine litho-facies and paleoclimate cycles. • Strong orbital eccentricity-paced paleoenvironmental changes are revealed. • An ~11.14 Myr astrochronology is established for the Shahezi Formation. [ABSTRACT FROM AUTHOR]