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High‐pressure hydrogen direct injection technology can enable an internal combustion engine to attain high thermal efficiency and discharge clean emissions; hence, the advantages provided by hydrogen jet impingement are crucial. This paper presents an experimental investigation of the high‐pressure hydrogen direct injection from a single‐hole cylindrical injector. A test rig with a spring set was designed based on the impulse conservation law to test important high‐pressure hydrogen jet impingement parameters, such as jet impingement force and impulse. The results show that the hydrogen gas jet exhibits a two‐zone behavior. In Zone I (near‐field dynamic region), the jet impulse is not conservative, and the jet characteristic parameters (jet impingement force and impulse) fluctuate—first decreasing and then increasing. In Zone II, the jet impulse is conservative. This two‐zone jet feature is induced by shockwaves because a high‐pressure hydrogen jet with a high nozzle pressure ratio reaches its sonic speed at the nozzle outlet. The Mach disk height is the inflection point of these two zones. Moreover, the hydrogen injection pressure has a considerable influence on the gas jet. As the injection pressure increases, the hydrogen jet impingement force and impulse increase. Both jet parameters have a linearly increasing relationship with injection pressure. [ABSTRACT FROM AUTHOR]

The coupling of Eulerian and Lagrangian methods in the Eulerian–Lagrangian Spray Atomization (ELSA) approach is critical. This study proposes an equation for the primary breakup particle diameter D of a diesel fuel spray and adopts it as a key transition criterion for coupling. A three-dimensional diesel spray is modeled by the large-eddy simulation (LES) approach. This improved ELSA simulation was conducted using various transition criteria for particle diameter Dcr. The results show that fuel spray experiences two stages: stage I, when a liquid column appears without a dispersed phase, and stage II, when primary breakup occurs with many discrete particles. Although Dcr has little influence on the macro-spray characteristics, such as top penetration distance S and spray cone angle θ, it has significant effects on discrete particles, such as their number, average diameter, distribution and location, and spray cone area. Dcr should be determined on the basis of actual operating conditions. [ABSTRACT FROM AUTHOR]

Zircons from two high-pressure granulite samples from the Yushugou ophiolitic terrane, southern Tianshan have been investigated by cathodoluminescence, LA- ICPMS and ion microp robe (SHRIMP) for their internal textures, trace elemental compositions and in situ dating. The weighted mean ages of these two samples are 392±7 and 390± 11 Ma, respectively, representing the granulite-facies metamorphic age of the ophiolitic terrane, and indicating that the southern Tianshan ocean initiated its northward subduction since the early Devonian. [ABSTRACT FROM AUTHOR]

Presents a study that examined the geochemistry of basic dykes in the Wudang block of south Qinling, China and discussed their tectonic significance. Regional geology; Geochemistry of the basic dykes; Origin and tectonic implications.

Presents a study that focused on the strontium, neodymium, lead and oxygen isotopes of basic dyke swarms in the Wudang Block and basic volcanics of the Yaolinghe Group in China. General geology; Sample and analysis; Isotope geochemistry of the elements.

The chemistry of the basic volcanic rocks at the south margin of the Qinling orogenic belt (SMQOB) suggests that they were formed in an intraplate tectonic setting. The REE distribution patterns show these rocks are strongly enriched in LREE with high ΣREE, and their trace elements geochemistry is similar to that of continental flood basalt. All the above evidence suggests that the Caledonian basic volcanic rocks in the SMQOB were tholeiitic basalts formed in an intraplate spreading-initial rift tectonic setting. The characteristics of regional geology and geochemistry indicate that there was an intraplate spreading-rift tectonic setting between the South Qinling block and the Yangtze block in the Caledonian epoch. The dynamic spreading in this district began in the Early Caledonian and then the intraplate spreading-initial rifts were formed in the late Caledonian. As a result of spreading of the Tethys and geodynamic processes in deep mantle, the Mianlue-Huashan oceanic basin was formed between the Qinling block and the Yangtze block in Devonian, and the Qinling microplate was separated from the northern part of the Yangtze plate. [ABSTRACT FROM AUTHOR]

Focuses on the geological significance of the basic dyke swarms in the Wudang block in China. Geochemical characterization by continental tholeiites; Samarium-neodymium age; Presence of an ancient continental block in the Proterozoic.

Because few well-preserved hydrothermal chimneys have been found in terrestrial sedimentary rocks, research on paleo-thermal vents in geological history is relatively sparse. In this study, we present our original discovery of "hydrothermal chimneys" from the Chang 7 source rocks of the Triassic Yanchang Formation in the Ordos Basin, China, and provide the best evidence for deciphering hydrothermal activity preserved in the geological record (i.e., sedimentary rocks). Three possible chimney samples (i.e., samples 1551.6, 1551.6–2 and 1574.4) were collected for this study; they were interbedded with mudstones and oil shales, indicative of a deep-lake sedimentary environment. All three samples consist mainly of anhydrite, pyrite, and dolomite with the formation of mineral zoning across the walls of these structures, suggesting a sulfate-dominated stage and a carbonate-sulfide replacement stage. Moreover, their in situ geochemistry is characterized by high Eu, U, Th, Sr, Mn and U/Th ratios, which are typical indicators of hydrothermal vents. In addition, their S isotopes range from 7.89% to 10.88%, near the values of magma sulfur, implying a possible magmatic trigger for these hydrothermal vents. All this evidence shows that the Triassic sedimentary rocks of the Ordos Basin probably contain hydrothermal chimneys. Comparing ancient hydrothermal chimneys to modern hydrothermal chimneys, we should note the important implications of ancient chimneys; their formation mechanism may have been related to oil production, and they are possible indicators for future oil investigations. Further, they have great significance for studying the hydrothermal properties of primary dolomite. [ABSTRACT FROM AUTHOR]

Lithotypes, organic matter, and paleoenvironment characteristics are essential attributes in organic-rich lacustrine mudstone. Understanding the covariant relationship among them is significant not only for revealing the main controlling factors of organic matter accumulation but also for optimization of the favourable interval of unconventional petroleum resources. Herein, we present a systematic petrological and geochemical analysis of 24 samples collected from the Chang7 3 submember in the Triassic Yanchang Formation. Base on the texture, bedding, and composition of mudstone, the collected samples can be further divided into four lithotypes (Lithotype1 to Lithotype 4). Toc and rock pyrolysis data indicate that those four lithotypes mainly contain a high content of type I and II 1 kerogen, good to excellent hydrocarbon generation potential, and are at the low mature to mature stage. Paleoenvironmental parameters, represented by paleosalinity (Sr/Ba, B/Ga), sediment provenance (Al 2 O 3 /TiO 2 and Th/Sc–Zr/Sc), paleoclimate (C-value, Sr/Cu), paleoproductivity (P/Al, P/Ti, Ni/Al, Ni/Ti, Cu/Al, and Cu/Ti), bottom-water redox conditions (V/Cr, V/(V + Ni), and U EF -Mo EF), and sedimentation rate ((La/Yb) N), indicate that the four lithotypes were all deposited in freshwater environments and sourced from felsic volcanic rocks but different in the paleoclimate, paleoproductivity, bottom-water redox conditions, and sedimentation rate. According to the ratios of C-value, B/Ga, Al 2 O 3 /TiO 2 , P/Ti V/Cr and (La/Yb) N with TOC, The degree of organic matter accumulation is positively correlated with the humidity of the paleoclimate, paleoproductivity, and reducibility of bottom water but negatively related to the sedimentation rate. Comparing the differences between the organic matter characteristics and paleoenvironment of the four lithotypes, we conclude that Lithotype1 is the most favourable target lithotype for developing unconventional oil resources. • Four lithotypes are identified in the Chang7 3 organic-rich lacustrine mudstone. • A relationship among lithotypes, OM abundance, and palaeoenvironment is established. • Four main controlling factors for OM accumulation are revealed. • The most favourable hydrocarbon generation lithotype is selected. [ABSTRACT FROM AUTHOR]

To investigate primary breakup close to an injector, this paper presents both experimental and numerical research on high-pressure common-rail diesel injection. We propose a new method named SD-ELSA model to realize automatically identifying droplet features for high-pressure diesel spray based on the classic ELSA (Eulerian Lagrangian Spray Atomization) model; this method is suitable for varied injection operation conditions. The SD-ELSA first identifies the liquid bulk due to breakup of the continuous phase in near field, and then converts the Eulerian liquid bulk into Lagrangian particles to complete the calculation of the total spray atomization. The SD-ELSA model adopts two key criteria, i.e., the sphericity (S) and the particle diameter (D); the qualified liquid mass is transformed into Lagrangian particle, realizing the coupling of the Eulerian–Lagrangian model. The SD-ELSA model illustrates the total diesel spray atomization process from the breakup liquid column to the droplets. [ABSTRACT FROM AUTHOR]

The Permian mafic dykes of Santanghu Basin offer an opportunity to study the nature of mantle source and tectonic setting of the basin, as well as to provide the theoretical basis for structural transformation of East Junggar region. In this study, zircon U–Pb geochronology, mineral composition analysis, whole‐rock elemental, and Sr‐Nd isotopic geochemistry were conducted to explore the origin and evolution of the primitive magma. LA‐ICPMS zircon U–Pb dating yields ages at 269 Ma. The elemental geochemistry results suggest enrichments in Ba, Pb, and Sr but depletions in Nb, Ta, Zr, and Hf, which indicate that the magma source was influenced by fluid metasomatism. All samples show moderate initial Sr‐Nd isotope results ((87Sr/86Sr)I = 0.704299 to 0.704490 and εNd(t) = +6.16 to +6.83) and have high Sm/Yb ratios, which suggest that the diabases were derived from partial melting of 5%–7% spinel‐garnet Iherzolite lithospheric mantle. Combined with petrological, geochronological data, and the regional tectonic background, it is interpreted that the diabases from Santanghu Basin originated from lithospheric mantle metasomatized by subduction fluids under the background of intracontinental extension. [ABSTRACT FROM AUTHOR]

The Ordos Basin is a large depression-type lake basin in the late Triassic. Here, we present a study on Yufenites, which were found in the BWZ (BaWangZhuang) section, TNH (TangNiHe) section and Well Z11 in the Tongchuan area on the southern margin of the basin and in the lower shale layer of Chang 7 member in Triassic Yanchang Formation. Yufenites are slightly flattened spindle-shaped fossils, pointed and thin, with obvious spiral patterns on the surface. The spiral starts from the thin part and turns from right to left, and the pitch changes from narrow to wide. The Yufenites contains animal and plant residues that have not been completely digested, and a large number of mineral aggregates that formed around phosphorus-containing dolomite as a growth base. Yufenites had a high viscosity and strength when discharged. Due to the action of microorganisms, the diagenesis of Yufenites occurs earlier and faster than that of the surrounding rocks. Based on this description, we believe that this Yufenites is from a large carnivorous fish. In the Late Triassic, humid and hot climatic conditions, low water kinetic energy, desalinated water, high productivity, magmatic-hydrothermal activity and other factors played an important role in the preservation of Yufenites. [ABSTRACT FROM AUTHOR]

The Sulu Orogen preserves the Neoproterozoic tectonic-magmatic events, corresponding to the breaking up of the Rodinia supercontinent. The ages and petrogenesis of meta-igneous rocks in the Liansandao area in the northern Sulu Orogen are not well-constrained. This study reports zircon U-Pb ages and Hf isotopes of these rocks from the Liansandao area. Three meta-igneous rock samples give similar weighted mean 206Pb/238U ages of 744±11, 767±12, and 762±15 Ma, respectively, indicating the Neoproterozoic crystallization ages. These rocks formed coevally with the Wulian and Yangkou intrusions that located along the Yantai-Qingdao-Wulian fault zone. The Neoproterozoic ages indicate that the meta-igneous rocks from the Liansandao area have affinity to the Yangtze Block. The three samples have εHf(t)Hf(t) values of -7.2–-10.5, -6.0–-17.5, and -6.8–-12.0, respectively. These negative εHf(t) values indicate a primarily crustal source. However, the widely various εHf(t) values that are higher than the continental crust, suggesting magma mixing between mantle-derived materials and the continental crust or source heterogeneity. Combined with the Hf model ages and geochemical characteristics, the monzodiorite (sample LSD-2) is most likely to be mantle-derived magma then interacted with ancient continental crust, and the granitic protolith (samples LSD-1 and LSD-3) in the Liansandao area might derive from the re-melting of a Paleoproterozoic continental crust at ~750 Ma, resulting from the upwelling and underplating of mantle-derived magma formed in an extensional setting due to the break- up of the Rodinia supercontinent. [ABSTRACT FROM AUTHOR]

The article focuses on findings of a study on geochemical characteristics and geological significance of picritic rocks in Permian Tiaohu Formation from Santanghu Basin, Xinjiang of China. Topics include magmatic activity of Permian in Santanghu Basin; characteristics of picritic rocks, such as SiO2 amount of picritic rocks; and voluminous postcollisional granitoids and Armantai and Karamaili suture zone formation age.

The cycling of various isomorphs of authigenic silica minerals is a complex and long-term process. A special type of composite quartz (Qc) grains in tuffaceous shale of Permian Lucaogou Formation in the sediment-starved volcanically and hydrothermally active intracontinental lacustrine Santanghu rift basin (NW China) is studied in detail to demonstrate such processes. Samples from one well in the central basin were subject to petrographic, elemental chemical, and fluid inclusion analyses. About 200 Qc-bearing laminae are 0.1-2 mm and mainly 1 mm thick and intercalated within tuffaceous shale laminae. The Qc grains occur as framework grains and are dispersed in igneous feldspar-dominated matrix, suggesting episodic accumulation. The Qc grains are bedding-parallel, uniform in size (100 s µm), elongate, and radial in crystal pattern, suggesting a biogenic origin. Qc grains are composed of a core of anhedral microcrystalline quartz and an outer part of subhedral mega-quartz grains, whose edges are composed of small euhedral quartz crystals, indicating multiple episodic processes of recrystallization and overgrowth. Abundance of Al and Ti in quartz crystals and estimated temperature from fluid inclusions in Qc grains indicate that processes are related to hydrothermal fluids. Finally, the Qc grains are interpreted as original silica precipitation in microorganism (algae?) cysts, which were reworked by bottom currents and altered by hydrothermal fluids to recrystalize and overgrow during penecontemporaneous shallow burial. It is postulated that episodic volcanic and hydrothermal activities had changed lake water chemistry, temperature, and nutrient supply, resulting in variations in microorganic productivities and silica cycling. The transformation of authigenic silica from amorphous to well crystallized had occurred in a short time span during shallow burial. [ABSTRACT FROM AUTHOR]

The Maoniushan Formation in the northern part of the North Qaidam Orogen (NQO), NW China, contains key information on a Paleozoic change in tectonic setting of the NQO from compression to extension. Here, new zircon U–Pb, petrological, and sedimentological data for the lower molasse sequence of the Maoniushan Formation are used to constrain the timing of this tectonic transition. Detrital zircons yield U–Pb ages of 3.3–0.4 Ga with major populations at 0.53–0.4, 1.0–0.56, 2.5–1.0, and 3.3–2.5 Ga. The maximum depositional age of the Maoniushan Formation is well constrained by a youngest detrital zircon age of ∼409 Ma. Comparing these dates with geochronological data for the region indicates that Proterozoic–Paleozoic zircons were derived mainly from the NQO as well as the Oulongbuluk and Qaidam blocks, whereas Archean zircons were probably derived from the Oulongbuluk Block and the Tarim Craton. The ∼924, ∼463, and ∼439 Ma tectonothermal events recorded in this region indicate that the NQO was involved in the early Neoproterozoic assembly of Rodinia and early Paleozoic microcontinental convergence. A regional angular unconformity between Devonian and pre-Devonian strata within the NQO suggests a period of strong mountain building between the Oulongbuluk and Qaidam blocks during the Silurian, whereas an Early Devonian post-orogenic molasse, evidence of extensional collapse, and Middle to Late Devonian bimodal volcanic rocks and Carboniferous marine carbonate rocks clearly reflect long-lived tectonic extension. Based on these results and the regional geology, we suggest that the Devonian volcano-sedimentary rocks within the NQO were formed in a post-orogenic extensional setting similar to that of the East Kunlun Orogen, indicating that a major tectonic transition from compression to extension in these two orogens probably commenced in the Early Devonian. [ABSTRACT FROM AUTHOR]

Shales in the middle Permian Lucaogou Formation in the intracontinental Santanghu rift basin have been considered as “typical” organic-rich profundal shales for decades. Our study of well cores using petrographic microscope and scanning electron microscopy suggests an otherwise complex hydrovolcanic and hydrothermal origin. This paper describes characteristics of a particular type of the shales, composed of fine-grained detrital minerals and lithic grains. Some of them are orthopyroxene, calcite, peralkaline feldspars, and analcime that are interpreted as derived from peralkaline-alkaline carbonatite, pyroxenite, analcime phonolite, and andesite, whereas others are quartz, dolomite, ankerite, serpentine, and calcite that were precipitated from syndepositional or penecontemporary hydrothermal fluids. Grain size ranges from 0.001 to 2 mm, mostly 0.01–0.1 mm. Well-developed laminae are mostly 0.5–3 mm thick and alternate with tuffaceous dolomicrite. The rocks are interpreted as sublacustrine hydrovolcanic deposits, which had been altered by syndepositional hydrothermal fluids. The interpretation is substantiated by abundant cone-shaped stratigraphic buildups on seismic sections in the basin. This study shows an ancient example of volcanic-hydrothermal deposits in a rift basin. [ABSTRACT FROM AUTHOR]

Tuffs, produced by explosive volcanic eruptions, are widely deposited throughout the Precambrian to Cenozoic stratigraphic record. Due to rapid compaction and erosion, preservation and identification of tuffs in distal environments are challenging. However, in deep lacustrine environments, tuffs may be found well-preserved as interlayers in the organic-rich mudstone. This in turn provides valuable insights into the origin, transport, and diagenesis of volcanic material. In this study, we performed an integrated sedimentological, mineralogical, and geochemical analysis of seven tuff samples collected from the lower part of the Chang7 member of the Maquan section to infer on their provenance, transport mechanisms and post-depositional alterations. Immobile element ratios, tectonic discrimination diagrams, trace element distribution patterns, and negative whole-rock εNd(t) reveal an intermediate to felsic continental arc source of the studied tuff. Supported frameworks and ash aggregates in the tuff are in favor of the transport from pyroclastic density currents and ash plumes during multiple volcanic eruptions with various degrees of eruption volume and water content. Tuff diagenesis is characterized by dissolution of plagioclase, illitization of smectite, cementation of carbonate minerals, and presence of buddingtonite. Relatively ordered illite-smectite and low vitrinite reflectance from the adjacent organic-rich mudstone indicate diagenetic evolution of studied tuff have reached mesogenetic stage. • The tuffs of Chang7 member originated from felsic magmas at continental-arc setting. • The tuffs were transported by pyroclastic density current and ash plumes with various eruption volume and water content. • The tuffs have evolved to mesogenetic stage. [ABSTRACT FROM AUTHOR]

Santanghu area in northeastern Xinjiang region of Northwest China is an important component of the Central Asian Orogenic Belt (CAOB), in which the dynamic mechanism of Permian magmatism is controversial. In Santanghu area is exposed a thick succession of the Middle Permian basalts, including a small amount of picritic basalts and andesites, known as the Tiaohu Formation. The picritic basalts contain cumulate olivine, and have whole-rock Mg up to 0.68-0.77; the basalts exhibit porphyritic or doleritic textures, and have relatively low Mg of 0.41-0.54, typical of evolved magmas. The mafic-ultramafic rocks of the Tiaohu Formation are slightly enriched in Light Rare Earth Elements (LREEs), and exhibit negative Nb and Ti anomalies. They also have high TiO content, and Nb/Y and Zr/Yb ratios greater than those of island arc volcanic rocks. Relatively low initial Sr isotopic ratios and high positive ɛ( t) and ɛ( t) values argue against contamination by ancient continental crust, and suggest formation of the Tiaohu Formation by partial melting of relatively refractory depleted lithospheric mantle that underwent metasomatism and extraction by fluid from the subducted slab. In addition, up to 38% olivine in picritic basalts indicates high-degree partial melting of lithospheric mantle, and the underlying Lucaogou Formation contains fragments of ultra-alkaline magmatic rocks that originated in the deep mantle. These observations imply wide-spread underplating in Santanghu area, which may have been associated with a mantle plume. [ABSTRACT FROM AUTHOR]

The coupling relationship between volcanic-hydrothermal activities and hydrocarbon generation has been a common understanding in recent years. However, there is a lack of theoretical and practical guidance in the application hydrocarbon production. The fine-grained sedimentary rocks of the middle Permian Lucaogou Formation in the Jimsar Sag in the Junggar Basin, NW China, are critical source rocks and have been simplify regarded as a mudrocks for target for tight oil exploration. Recently studies show that rocks were deposited in an intracontinental lacustrine environment with multiple volcanic-hydrothermal activities. Their complex micro-scale lithological characteristics restrict the understanding and further exploration and development of tight oil. Hence, this study focuses on the detailed lithological and their organic geochemical characteristics of the Lucaogou Formation using microscopic thin-section observation, scanning electron microscopy, X-ray diffraction, Rock-Eval, saturated hydrocarbon chromatography and mass spectrometry. The following key conclusions were obtained. First, the massive mudrocks are sub-divided into lithofacies for hydrocarbon generation, including tuffaceous shale, calcareous shale and dolomitic shale, and, microinterval reservoirs, including dolostone and sedimentary tuff. Second, the origins of organic matter in Lucaogou Formation were mainly plankton, bacteria with minor of land plants. The depositional environment is high salinity and anoxic conditions. Materials derived from volcanic-hydrothermal activities, lacustrine precipitation, and terrestrial transportation mixed with various proportions to form this formation. Third, a mixture of carbonate minerals, felsic minerals and clay minerals is the best source rock, and the higher the mixture, the better. This research not only provides insight into the influence of volcanic-hydrothermal activities on lithology and organic matter enrichment, but also providing a potential scheme for the tight oil exploration and development in similar rifted geological settings. • A mixture lithology of carbonate minerals, felsic minerals and clay minerals is the best source rock. • The better the mixture of carbonate minerals, feldspar minerals and clay minerals, the better the quality of hydrocarbon source rock. • Volcanic-hydrothermal activities are favorable to the enrichment and preservation of organic matter. • The Lucaogou formation was formed in a high salinity and anoxic condition, and the biological source was mainly plankton. [ABSTRACT FROM AUTHOR]

Highlights: [•] The Liupanshan area experienced multistage deformation process since the Cenozoic. [•] Initial sinistral strike-slip shear occurred in 57–61Ma in the Liupanshan area. [•] The Indian and Eurasian collision should be earlier than 57–61Ma. [Copyright &y& Elsevier]

The Santanghu area is located on the northeastern margin of the Junggar Basin, northern Xinjiang, Northwest China. The Carboniferous volcanic rocks in this area are widely distributed in Kaokesaiergaishan, Santanghu, Daheishan and Naomaohu districts, which are located to the north of the Kalameili Fault. These rocks, sourced from a cognate magma, consist of basic, intermediate, and acidic lavas, and pyroclastic rock. The basic volcanic rocks are enriched with large-ion lithophile elements (LILE), but are relatively depleted in high field strength elements (HFSE), and have an obvious negative Nb-Ta-Ti anomaly. They were most probably derived from a depleted mantle source, and during their ascent, these magmas were not contaminated by the crustal material as they underwent magma crystallization differentiation. Based on the Carboniferous volcanic assemblage and geochemical data, it is apparent that the early Carboniferous volcanism occurred in a subduction-related tectonic setting. New LA-ICP-MS zircon U-Pb analyses constrain the age of the andesite within the volcanic rocks as the early Carboniferous (328.9-331.3 Ma). Combined with the regional geological record, comprehensive analysis of the isotope geochronological data indicates that the subduction of the Junggar Ocean predates the early Carboniferous, and that the Santanghu island arc magmatism was induced by the subduction of the Junggar Ocean in the Carboniferous. [ABSTRACT FROM AUTHOR]

The Permian Lucaogou Formation is an important hydrocarbon source rock in the Junggar, Turpan, and Santanghu basins in Xinjiang, NW China. For the first time, dolostones associated with mantle-originated exhalative hydrothermal fluid flows are discovered in Yuejingou section in the Santanghu Basin area. They include dolomicrite, doloarenite, and a small amount of dolorudite, and are finely (0.05-0.15 cm thick) interlaminated with lime micrite and dolomicritic analcime laminites. Alkali feldspar and analcime grains are common in doloarenite and are interpreted as having been derived from analcime phonolites and peralkaline magmatic rocks. These magmatic fragments were brought up from subsurface by hydrothermal fluid flow and had experienced exhalative brecciation, transport, and deposition on the lake floor. The matrix consists dominantly of dolomite and ankerite smaller than 0.01 mm. The dolostones can be subdivided into four types on the basis of mineral composition and content. The detrital analcime and alkaline feldspar grains and tuff lithics are interpreted as intraclasts, which were deposited in an under-filled starved lake basin. The δ values of dolostones are −5‰ to −21.1‰, and −11.9‰ on average; the Sr/Sr ratios of dolostones are 0.70457 to 0.706194, and 0.705005 on average. These values, in combination with evidence of multi-episodes of peralkaline extrusion, suggest a mantle origin of the hydrothermal fluids, which may have promoted primary dolomite formation. The fluid from the upper mantle caused serpentinization of ultramafic rocks that intruded into the lower crust to obtain Mg and Fe, and injected the ions into the lake water as the Mg and Fe sources for dolomite and ankerite. Hydrothermal fluids associated with peralkaline magmatic rocks also provided Ca, Mg, Fe, and CO. Explosive breccias formed and dolostones were convoluted near the vent of hydrothermal fluid exhalation, whereas laminated dolostones formed farther away from the vent. The dolostones are primary dolomite deposition in an intracontinental rift basin and associated with mantle-originated hydrothermal fluids. They provide an insight into the origin of dolomite formation in the geologic history and clues to understand the sedimentary environments and tectonic conditions in northern Xinjiang during the late Paleozoic. [ABSTRACT FROM AUTHOR]

Abstract: A preliminary Early–Late Permian mid-latitude continental climatic record in NW China was interpreted mainly from sedimentary climate indicators and type and stacking pattern of depositional systems and cycles in a 1178-m fluvial–lacustrine section. Depositional systems analysis delineated five types of primary fluvial and lacustrine depositional cycles, which were grouped into three (high, intermediate, and low) orders. Semi-arid, subhumid, and humid climate types in terms of relative precipitation/evaporation ratio were interpreted and climate variability was identified at sub-cycle and high, intermediate, and low-order cycle scales. Early Kungurian climate fluctuated between subhumid to humid and middle–late Kungurian climate shifted gradually from subhumid/semi-arid to semi-arid. Roadian climate fluctuated widely from humid to semi-arid with strong precipitation seasonality at sub-cycle and high-order cycle scales. Wordian climate was dominantly humid with short subhumid intervals and ended with a peak semi-arid condition. Capitanian climate was mainly subhumid to humid, as the start of a long interval of dominantly humid, strongly wet–dry conditions into the Wuchiapingian time. The late Kungurian–Wordian semi-arid condition is incompatible with modern mid-latitude east-coast humid climate, suggesting different mechanisms operating in Pangea and Panthalassa. The highly variable Roadian–Wordian climate may have started terrestrial mass extinction that climaxed at the end of Permian. [Copyright &y& Elsevier]

Reports the zircon ion microprobe (SHRIMP) dating results for Songshugou garnet pyroxenite and Fushui gabbro. Suggestion that the Fushui gabbro-diorite complex body possesses characters of Alaska-type island-arc mafic-ultramafic plutonic complex which is an important component of the island-arc magmatic belt; Kinds of rocks that constructed the Early Paleozoic tectonic pattern of plate subduction and collision; Implications for the understanding of the tectonic evolution of the Qinling Orogenic Belt.

The Chang 7 oil shales of the Triassic Yanchang Formation in the southern margin of the Ordos Basin has been a concern of researchers because of the extensive development of lacustrine hydrothermal sedimentary rocks in it. Here, we studied the petrological and mineralogical characteristics of hydrothermal sedimentary rocks through ordinary thin sections, scanning electron microscope and electron probe observations, and evidences about hydrothermal activity were identified from the oil shales. On this basis, we further complete their geochemical analysis. The results show that the Cs, U, Th, Pb, and Mn of the Chang 7 oil shale have significant positive anomalies and that the Eu and Ta elements have negative anomalies. The TOC value of Chang 7 oil shale ranges from 0.18 wt% to 18.15 wt%, with an average value of 3.85 wt%. The average value of the Chang7-3 section is 5.33 wt%, the average value of the Chang7-2 section is 2.15 wt%, and the average value of the Chang7-1 is 3.05 wt%. In addition, the hydrothermal index of Chang 7 source rock shows: The correlation coefficient between the hydrothermal index and the TOC content is as high as −0.86 and 0.85. There is the most hydrothermal input in Chang7-3 deposition period, it was somewhat weakened in the Chang 7-2 deposition period, and it was enhanced in the Chang 7-1 deposition period. Hydrothermal deposition is involved in the hydrocarbon generation of oil shales. The greater the hydrothermal input intensity is, the greater the TOC content of the oil shale is. [Display omitted] • A variety of hydrothermal minerals and mineral combinations have been identified from black shale. • The influence of hydrothermal activity on Chang 7 oil shale was studied from the perspective of element geochemistry. • Longitudinal analysis of the relationship between drilling fluid input and organic matter abundance. [ABSTRACT FROM AUTHOR]

Lacustrine organic-rich shale (LORS) developed in the Chang 7–3 section of the Triassic Yanchang Formation in the Ordos Basin. LORS has been proven to be a source of crude oil and tight oil, as well as a source and reservoir for shale oil in the basin. A total of 35 LORS samples were collected from Well Z233 and analysed by mineralogy and element geochemistry to reveal the characteristics and controlling factors of LORS. The following results were obtained: ① In the oil shale, the organic matter is composed of type I and type II kerogen, with a predominance of type II. The organic matter is mature and reaches high levels of abundance. ②Through further analysis. The values of w(U)/w(Th), w(V)/w(Cr), w(Ni)/w(Co), the size and morphology of pyrite, indicates that the lake water of the LORS deposition period in the study area is anoxic or suboxic state. the TOC of the samples was found to have significant positive correlations with the w(Mo) and w(Ba bio) contents. Paleoproductivity can be inferred to be the key factor controlling organic matter enrichment in the LORS. ③Volcanic and hydrothermal activities promote the development of LORS, provide nutrients needed by organisms, promote the growth of organisms, and improve paleoproductivity. Hydrothermal activity leads to the formation of an anoxic environment at the bottom of the lake, and tuff will cover the sediments, which promotes LORS preservation. This study reveals in detail paleoproductivity is the main factor in the formation of LORS during the evolution of the basin. Volcanic and hydrothermal activities promoted the increase of paleoproductivity, and finally the oil shale layers with the richest organic matter have been formed. And thereby deepens our theoretical understanding of organic matter enrichment. • The organic matter types of oil shale are type I and type II, with type II being the main type. • The redox and paleoproductivity conditions for the development of Chang 7 LORS were analyzed. • It is believed that paleoproductivity is the key factor controlling the accumulation of organic matter in the study area. • The influence of volcanic and hydrothermal activity on LORS is analyzed. [ABSTRACT FROM AUTHOR]