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摘要:Two new fossil subgenera and two new fossil species of the genus Tipula Linnaeus, 1758, Tipula (Succinica) berendti subgen. and sp. n. and Tipula (Gedanica) adamowiczi subgen. and sp. n., are described from Baltic amber and compared with other species of Tipula known from the Eocene. The two new subgenera and species described herein are an excellent bridge between recent specimens and those preserved in sedimentary rocks, and thus enrich knowledge on the evolution of the family.

摘要:Two Upper Devonian to Lower Carboniferous sections, namely the Bulongguoer and Haer (Gennaren area) in the Junggar Basin, Central Asian Orogenic Belt, in northwestern China were examined with regard to ichnology and palynology. The deposits of the Hongguleleng Formation and Namu Member of the Heishantou Formation, respectively, are mostly unbioturbated or poorly bioturbated, with poorly diversified trace fossils, which indicate unfavourable conditions for the burrowing benthic community during the Late Devonian and Early Carboniferous. The main factor governing the growth of the bioturbating population was the rapid sedimentation of fine-grained, volcanic material documented as tempestites, which buried the benthic fauna. In the Bulongguoer section, the presence of miospores Teichertospora torquata and Grandispora gracilis enabled identification of the broad Teichertospora torquata–Grandispora gracilis Miospore Zone from the transitional Frasnian/Famennian interval. More accurate identification of palynostratigraphical levels (DE and CZ Miospore zones) is only tentative. On the basis of palynofacies analysis, samples from the lower Bulongguoer section indicate deposition in more proximal conditions, whereas samples from the top of the section indicate deposition in a more distal environment. In the Haer section, only a general biostratigraphic indication for the Tournaisian was possible, owing to poor preservation of organic matter.

摘要:It is unclear whether the South China blocks have an affinity with continental Gondwana due to a lack of direct Pan-African magmatic and metamorphic features. In this study, we conducted U-Pb geochronological and Lu-Hf isotopic analyses for detrital zircons from a sandstone of the Chang’an Formation of the Nanhua Group in the Longsheng region of northern Guangxi, with the aim of constraining the timing of sedimentation and information as to its source, as well as seeking evidence for Pan-African events in the South China blocks. The results show that the ages of detrital zircons peaked at 654.7 ± 6.2 Ma, 773.2 ± 4.1 Ma and 821.9 ± 6.5 Ma, with some at 920–870 Ma; the youngest age indicates the existence of the Pan-African thermal event. The εHf(t) and TDM2 values demonstrate that the study area has experienced three stages of crustal growth at 3.0–2.4 Ga, 2.1–1.5 Ga and 1.3–0.9 Ga. With intensively distributed Neoproterozoic mafic-ultramafic and granitic plutons emplaced at 830–810 Ma along the southwestern section of the Jiangnan Orogenic Belt and positive εHf(t) values from a large group of zircon grains, it is proposed that the sediments of the Chang’an Formation (of Nanhua Group) were largely sourced from the southeastern margin of the Yangtze block. Comparison with the zircon age spectra of the Cathaysian block shows that about 79% of the Pan-African aged detrital zircon grains that have TDM2 = 1352–1031 Ma and εHf(t) = 3.68–8.79, were sourced from the recycled Grenvillian crust of the Cathaysian block, suggesting that the Cathaysian block had a close connection with Gondwana.

摘要:The vorticity analysis technique was applied to measure the different lithological units, such as schist, metagranite and metavolcano-sedimentary rocks, which are present in the Halaban region. This work aims to interpret the relationship between the different lithologies and the tectonic setting, in order to elucidate the nature of kinematic analysis in the Halaban region. The kinematic analyses were applied to feldspar porphyroclasts, quartz and hornblende for twenty-six samples. The kinematic vorticity number (Wm) for deformed rocks in the study area ranged from ~0.6 to 0.9. The direction of the long axes for finite strain data (X axes) revealed a WNW trend with shallow dipping. The direction of the short axes for finite strain data (Z axes) were represented by vertical with associated horizontal foliation. The results of the kinematic vorticity and strain analyses are characterized by simple shear with different degrees of deformation in the Halaban region. Furthermore, our finite strain data shows no significant volume change during deformation. The subhorizontal foliation was synchronized with thrusting and deformation. Furthermore, throughout the overlying nappes, the same attitudes of tectonic contacts are observable, the nappes in the orogens being formed from simple shear deformation.

摘要:Magmatic microgranular enclaves (MMEs) are widely developed in the Shaocunwu granodiorite at the northeast margin of the eastern Jiangnan orogenic belt. Field geology showed that the MMEs occur as irregular ellipsoids near the edge of the intrusion, and consist of diorite, dominantly composed of amphibole, biotite, and plagioclase grains, with minor acicular apatite. Zircon U-Pb dating showed the ages of the host granodiorites and MMEs are 145.9 ± 1.1 Ma and 145.6 ± 2.5 Ma, respectively, indicating both originated during coeval late Jurassic magmatism. Whole-rock geochemical results show that the host granodiorite and MMEs have similar rare earth and trace element partition curves in spider grams, and similar 87Sr/86Sr, and 147Nd /144Nd isotope ratios, and their zircon 177Hf/176Hf isotopic ratios are similar. Geochemical studies indicate that both the host granodiorite and MMEs formed by mixing of coeval magma. Zircon Ti thermometers and oxygen fugacity of the host granodiorite and the MMEs show high oxygen fugacity, similar to that of W-Cu (Mo) mineralized granitoids in the eastern Jiangnan orogenic belt. A similar magma mixing process was probably one of the mechanisms that generated the W-Cu (Mo) fertile melts.

摘要:The Pamir Plateau can be divided into three secondary tectonic units from north to south: the North, the Middle and the South Pamir Blocks. The North Pamir Block belonged to the southern margin of Tarim-Karakum, thermochronological study of the Pamir structural intersection indicates that accretion of the Middle Pamir Block to the Eurasian Continental Margin and its subduction and collision with the North Pamir Block occurred in the Middle–Late Jurassic. Due to the Neo-Tethys closure in the Early Cretaceous, the South Pamir Block began to collide with the accretion (the Middle Pamir Block) of the Eurasian Continental Margin. Affected by the collision and continuous convergence between the Indian Plate and the Eurasian Plate since the Cenozoic, Pamir is in a multi-stage differential uplift process. During 56.1–48.5 Ma, North Pamir took the lead in uplifting, that is, the first rapid uplift in the Pamir region began there. The continuous compression and contraction of the Indian and Eurasian plates during 22.0–15.1 Ma forced the Pamir tectonic syntaxis to begin its overall uplift, i.e. Pamir began to enter the second rapid uplift stage in the Early Oligocene, which lasted until the Middle Miocene. During 14.6–8.5Ma, South Pamir was in a rapid uplift stage, while North Pamir was in a relatively stable state, showing asymmetry of tectonic deformation in the Pamir region in space. Since 6.5 Ma, Pamir began to rapidly uplift again.

摘要:During the Late Paleozoic, West Junggar (Xinjiang, NW China) experienced a shift in tectonic setting from compression to extension. Ha’erjiao is an important area for investigating collisional structures, post–collisional structures, and magmatic activities. Based on the petrological and geochemical characteristics of pyroclastic and other volcanic rocks in the Permian Kalagang Formation from the borehole ZKH1205 in the Jimunai Basin, the main types of source rock for the pyroclastic rocks deposited in the basin are identified and their implications for the Early Permian tectonic setting examined. The abundance of basalt and andesite lithic fragments in the pyroclastic rocks, together with the REE characteristics and the contents of transition and high field strength elements show that the source rocks were chiefly intermediate–basic volcanic rocks. High ICV values, low CIA values, low Rb/Sr ratios, low Th/U ratios and the mineralogical features suggest weak chemical weathering of the source rocks; the geochemical patterns of the pyroclastic rocks might not only have been impacted by crustal contamination but also might be related to the nature of the magma from the source area. The geochemical properties of the pyroclastic rocks distinguish them from arc-related ones, and such samples plot in the within-plate basalt (WPB) field in some diagrams. This is consistent with the formation background of the Early Permian volcanic rocks in this region.

摘要:This article presents the thermal transitions of a tobermorite-bearing sample when heated from 30°C up to 1200°C, both in vacuum and in static air, including tobermorite transforming to wollastonite, aragonite to calcite and calcite to lime. Characteristics obtained by in situ high temperature X-ray diffraction, field emission scanning electron microscopy and scanning transmission electron microscopy analyses jointly indicate that the investigated tobermorite is anomalous. The variations along the a, b, c axes and the volume changes of tobermorite with increasing temperature are described, and its thermal shrinkage coefficients therefore determined. The comparison between the refined structures at 30°C and 800°C demonstrates that the shrinkage degree (Δa/a0) along the a axis is higher than those (Δb/b0, Δc/c0) along the b and c axes. The wollastonite is formed in two ways: Tobermorite converting to wollastonite and lime reacting with quartz to form wollastonite.

摘要:Paleozoic rocks in the Wadi El Sahu area are affected by many major faults in different directions. A reverse fault trending NE-SW is exposed for about 300 m of its length as it cuts through the Abu Hamata and Adedia formations on the south side of Wadi El Sahu. A secondary ascending hydrothermal solution carrying heavy metals and radioactive minerals passed through the fault plain and the surrounding fractures, forming mineralized and radioactive zone. The mineralized zone thickness ranges from 60 cm to 200 cm along the fault plain. These rocks were analyzed radiometrically using a portable gamma-ray spectrometer, chemically by employing ICP-ES and ICP-MS, as well as mineralogically by both binocular and Environmental Scanning Electron microscope. Gold content was also determined by fire assay. REE and U contents reached up to 2682 and 1216 ppm, respectively. Mineralogical investigations indicated the presence of uraninite, torbernite, autunite, sklodowskite, kasolite as uranium minerals, thorite as a thorium mineral, monazite, allanite and xenotime as REE-bearing minerals, zircon and columbite as accessory minerals, gold and nickel as precious and base metals, in addition to cassiterite, chalcopyrite, chalcocite and chrysocolla. High REE and U contents are attributed to the circulation of epigenetic U and REE-bearing hydrothermal solutions along the fault plain and its surrounding fractures. Hydrothermal alteration processes could then be confirmed by the presence of the M-type tetrad effect in the REE-patterns of the ferruginous sandstone. The non-chondritic ratio of Nb/Ta, Zr/Hf and Y/Ho in the studied sandstone may be attributed to the tetrad effect. The Ce and Eu anomaly with unusual REE-patterns was represented by the presence of conjugated M-W tetrad effects, indicating either the dual effect of hydrothermal solutions or groundwater with seawater. The results clarify that the tetrad-effects could be used as evidence for the environment of deposition and as an indication for gold mineralization.

摘要:The Aghbolaq skarn deposit is located in the Urumieh-Golpayegan plutonic belt, NW Iran. The garnetite skarn (stage I) has been intensely cross-cut by the magnetite-garnet skarn (stage II) which were, in turn, cut and offset by the ore-hosting quartz veins/veinlets (stage III). The predominance of andradite (Adr82.5–89.1) and its high Fe3+/Al ratio (up to 1685) apparently supports the high fO2, salinity and prevalence of magmatic/hydrothermal fluids involved, rather than meteoric waters, during the magnetite-garnet skarn formation. Two major groups of fluid inclusions, namely aqueous (LV, LVS) and aqueous–carbonic (LVC, LLCVC), were recognized in garnet and quartz veins that, especially in growth zones and along intra-granular trails, better display fluid inclusion assemblages (FIAs) than those in clusters. The prograde magnetite-garnet skarn was formed by the metasomatic fluid at relatively high Th (209–374℃), under a lithostatic pressure of ~200 bars. The retrograde mineralized quartz veins were formed at temperatures ranging from 124℃ to 256℃, by dilute and less saline (2.57–11.93 wt% NaCl eq.) hydrothermal fluids under a hydrostatic pressure of ~80 bars. The fluid evolution of the Aghbolaq skarn began with an earlier simple cooling of metasomatic fluid during the prograde stage, followed by the later influx of low salinity meteoric fluids during the retrograde stage.

摘要:High-temperature geothermal water has abundant lithium (Li) resources, and research on the development and utilization of geothermal-type lithium resources around the world are increasing. The Qinghai–Tibetan Plateau contains huge geothermal resources; especially, Li-rich geothermal resources in southern Xizang, southwestern China, are widely developed. The Li-rich geothermal spots in Xizang are mainly distributed on both sides and to the south of the Yarlung Zangbo suture zone. Such resources are often found in the intensely active high-temperature Li-rich geothermal fields and, compared with other Li-rich geothermal fields around the world, the Li-rich geothermal fluid in the Xizang Plateau, southern Xizang is characterized by good quality: the highest reported Li concentration is up to 239 mg/L; the Mg/Li ratio is extremely low and ranges from 0.03 to 1.48 for most of the Li-rich geothermal fluid; the Li/TDS value is relatively high and ranges from 0.25–1.14% compared to Zhabuye Li-rich salt lake (0.19%) and Salar de Uyuni (Bolivia) (0.08–0.31%). Continuous discharge has been stable for at least several decades, and some of them reach industrial grades of salt lake brine (32.74 mg/L). In addition, elements such as boron (B), caesium (Cs), and rubidium (Rb) are rich and can be comprehensively utilized. Based on still-incomplete statistics, there are at least 16 large-scale Li-rich hot springs with lithium concentration of 20 mg/L or more. The total discharge of lithium metal is about 4300 tons per year, equivalent to 25,686 tons of lithium carbonate. Drilling data has shown that the depth is promising and there is a lack of volcanism (non-volcanic geothermal system). With a background of the partial-melting lower crust caused by the collision of the Indo-Asia continent and based on a comprehensive analysis of the tectonic background of southern Xizang and previous geological, geophysical, and geothermal research, deep molten magma seems to provide a stable heat source for the high-temperature Li-rich geothermal field. The Li-rich parent geothermal fluid rushes to the surface to form hot springs along the extensively developed tectonic fault zones in southern Xizang; some of the Li-rich fluid flows in to form Li-rich salt lakes. However, most of the Li-rich geothermal fluid is remitted to seasonal rivers and has not been effectively exploited, resulting in great waste. With the continuous advance of lithium extraction technologies in Li-rich geothermal fluid, the lithium resource in geothermal water is promising as a new geothermal type of mineral deposit, which can be effectively exploited. This is the first study to undertake a longitudinal analysis on the characteristics, distribution and scale, origin and utilization prospects of Li-rich geothermal resources in southern Xizang, research that will contribute to a deeper understanding of Li-rich geothermal resources in the area and attract attention to these resources in China.

摘要:The hydrogeochemical characteristics of geothermal fluids can reveal the genesis of geothermal systems and act as important references for developing and using geothermal resources. This study presents hydrogeochemical processes and thermal cycle mechanisms of typical geothermal fields in Western Sichuan. Based on the geological conditions in Western Sichuan, 29 hot springs in three geothermal fields in the Batang and Litang areas were selected for hydrochemical and isotopic (δD and δ18O) analyses. Furthermore, the temperature of the thermal reservoir was calculated and the upflow cooling process of the hot springs was analyzed. Most of the subterranean hot waters in Batang and Litang are of the HCO3-Na hydrochemical type. The ion variation in Batang is primarily affected by water-rock interactions. There is a strong positive correlation between Na+, B?, and Cl? in Litang, suggesting that they have the same material source. The Na+ and metaboric acid content is relatively high, which indicates that the groundwater runoff in both areas is relatively long-lasting, with reduced flow velocity; moreover, the metasilicic acid content is relatively high, which supports this conclusion. Both hydrogen and oxygen isotopes plot near the atmospheric precipitation line, indicating that groundwater recharge is functionally obtained from precipitation. The calculated thermal storage temperatures in Batang and Litang were 88–199°C and 96–154°C, respectively. The proportion of cold water mixing in Batang was 64%–67%, while that in Litang was 60%–68%. According to the calculated results, the initial thermal cycle depth of the Batang area (4540–4780 m) was greater than that of the Litang area (3150–3960 m). The enthalpy of the deep parental geothermal fluid in Batang was 1550 J/g with a Cl? concentration of 37 mg/L, while that in Litang was 2100 J/g with a Cl? concentration of 48 mg/L.

摘要:Carbonate concretions are conspicuous in organic-rich shales and are generally related to decomposition of organic matter. The black shales from the Chang 7 Member of the Upper Triassic Yanchang Formation of the southern Ordos Basin host abundant carbonate concretions, which provide a unique record of depositional and early diagenetic conditions of the paleo-lake sediments. However, little attention has been given to the genesis and growth processes of the concretions in these lacustrine petroleum source rocks. New petrographic observations and geochemical analysis show that the concretions are composed of calcite, phosphate fossil fragments, K-NH4-feldspar, quartz, bitumen, and minor Fe-dolomite. Phosphate minerals, mainly carbonate fluorapatite (CFA), show pervasive replacement by calcite, most of which contains phosphorus, ranging in concentration from 0.26 to 2.35 wt%. This suggests that the phosphate minerals are the precursors for concretion growth. Positive δ13C (+5.6 to +12.4 ‰ V-PDB) signatures and the absence of pyrite indicate that microbial methanogenesis was the dominant driver for concretion growth, rather than bacterial sulfate reduction. Quartz, bitumen, and Fe-dolomite are the last cements that occurred, at deep burial depths and high temperatures. The formation of phosphate minerals might have been induced by upwelling of phosphate-enriched deep water in the Late Triassic paleo-lake, which promoted phytoplankton blooms and further enrichment of organic matter. Extremely slow sedimentation rates of fine-grained detrital minerals, relative to dead organism accumulation, led to the high permeabilities of the organic-rich sediments and rapid concretion growth during shallow burial. The close association of phosphate-bearing carbonate concretions and organic-rich shales reflects that upwelling played a critical role in the formation of the high-quality petroleum source rocks in the Triassic paleo-Ordos lake.

摘要:Based on comprehensive analyses of occurrence, petrological observation, pore structure and geochemistry, the different reservoir characteristics and reservoir evolutionary pathways between different oolitic shoal reservoir types of the Feixianguan Formation on the west side of the Kaijiang-Liangping Trough have been studied. There exist three stages of high-energy slope break belts in the Feixianguan period, the corresponding three stages of oolitic shoals gradually migrating in the direction of the trough. Three types of oolitic shoal reservoirs, namely, residual-oolitic dolomite, mold-oolitic dolomite and sparry oolitic limestone, were formed during sedimentary-diagenetic evolution, the pore types being intergranular dissolved pore, mold pore (or intragranular dissolved pore) and residual intergranular pore, respectively. The petrology, physical properties and pore structure of the different types of oolitic shoal reservoirs are quite different. Residual-oolitic dolomite reservoirs have the best quality, while sparry oolitic limestone reservoirs have the poorest. Combined with analyses of trace elements, rare earth elements and carbon-oxygen isotopes, it is suggested that the formation of residual-oolitic dolomite reservoirs is jointly controlled by penesaline seawater seepage-reflux dolomitization and hydrothermal dolomitization. Mold-pore oolitic dolomite reservoirs are controlled by penesaline seawater seepage-reflux dolomitization and meteoric water solution. The burial dissolution of organic acid not only further improves the reservoir qualities of previously formed oolitic dolomite reservoirs, but also preserves residual intergranular pores in the sparry oolitic limestone reservoirs.

摘要:The Shahejie Formation is a fundamental rock unit for hydrocarbon exploration and production in the Nanpu Sag, Bohai Bay Basin. Methodology including thin sectioning, core observations, fluorescence, scanning electron microscopy, cathodoluminescence, fluid inclusion, laser scanning confocal microscopy and geochemical analysis (C, O isotopes) were all utilized to investigate the reservoir characteristics and origin of the Es? Sandstone. Thin section study showed that the reservoir rock consisted of feldspathic litharenite and lithic arkose. The reservoir pores are categorized as intergranular pores, fracture pores, dissolution pores and intergranular cement dissolution pores. The studied sandstone had good porosity (0.05%–35%) and permeability (0.006–7000 mD). The Es? reservoir is classified as a fractured reservoir, a primary intergranular pore-associated reservoir and a dissolution reservoir. Deposition, diagenesis and tectogenesis are the main factors that played important roles in the development of the reservoir. Sedimentation is the foundation and assumption for reservoir development, but the effective reservoir is primarily controlled by primary pores, fractures, lithofacies, tectonic elements and dissolution pores. Moreover, compaction, fracture filling and cementation were the primary sources of reservoir densification. The reservoir was progressively formed through the influence of different geological and diagenetic events. The present study provides significant information and references for hydrocarbon exploration and development in the Nanpu Sag.

摘要:With the implementation of the production tests in permafrost and offshore regions in Canada, US, Japan, and China, the study of natural gas hydrate has progressed into the stage of technology development for industrial exploitation. The depressurization method is considered as a better strategy to produce gas from hydrate reservoirs based on production tests and laboratory experiments. Multi-well production is proposed to improve gas production efficiency, to meet the requirement for industrial production. For evaluating the applicability of multi-well production to hydrate exploitation, a 2D model is established, with numerical simulations of the performance of the multi-well pattern carried out. To understand the dissociation behavior of gas hydrate, the pressure and temperature distributions in the hydrate reservoir are specified, and the change in permeability of reservoir sediments is investigated. The results obtained indicate that multi-well production can improve the well connectivity, accelerate hydrate dissociation, enhance gas production rate and reduce water production as compared with single-well production.

摘要:This study aimed to show anisotropic poroelasticity evolution in ultra-low permeability reservoirs under pore pressure, confining pressure, and temperature. Several groups of experiments examining Biot’s coefficient under different conditions were carried out. Results showed that Biot’s coefficient decreased with increased pore pressure, and the variation trend is linear, but the decreasing rate is variable between materials. Biot’s coefficient increased with increased confining pressure; the variation trend is linear, but the increasing rate varies by material as well. Generally, Biot’s coefficient remains stable with increased temperature. Lithology, clay mineral content, particle arrangement, and pore arrangement showed impacts on Biot’s coefficient. For strong hydrophilic clay minerals, expansion in water could result in a strong surface adsorption reaction, which could result in an increased fluid bulk modulus and higher Biot’s coefficient. For skeleton minerals with strong lipophilicity, such as quartz and feldspar, increased oil saturation will also result in an adsorption reaction, leading to increased fluid bulk modulus and a higher Biot’s coefficient. The study’s conclusions provide evidence of poroelasticity evolution of ultra-low permeability and help the enhancing oil recovery (EOR) process.

摘要:Development of sulfuric acid speleogenetic mineral deposits within cavernous middle Eocene beds of the Pyramids plateau is linked to hydrocarbon gas seepages. The work carried out field observations, binocular, polarizing, scanning and transmitted electron microscopy investigation, X-ray diffraction and X-ray fluorescence analyses. The morphological and petrographic features and chemical composition of the studied mineral deposits reveal a hypogene sulfuric acid speleogenesis. A model comprised of the following stages can be used to explain the presence of these features. (1) Ascent of hydrogen sulfide (H2S) gas associated with hydrocarbon seepages from the Cretaceous reservoirs under reducing conditions followed by oxidation to sulfuric acid (H2SO4), (2) descent of carbonic acid (H2CO3)-rich solution generated from surface sources, (3) reaction of H2SO4 and H2CO3 with the calcareous and argillaceous host rocks, (4) formation of H2SO4 speleogenetic by-products represented by natroalunite, aluminium-phosphate-sulfate, hydrated halloysite and Fe/Mn oxides within the replacive gypsum, and (5) subsequent stresses due to the formation of nearby stratiform cavities gave rise to the development of fractures/veinlets filled with displacive fibrous satinspar gypsum. The study sets the paleokarst features of the Giza Pyramids plateau within a hypogene sulfuric acid karst system developed by the action of groundwater containing H2S, H2SO4 and H2CO3.

摘要:This research investigated anthropogenic inputs and chemical weathering in the upper reaches of the Datong River Basin, a tributary of the upper Yellow River, NW China. Multiple approaches were applied to data from 52 water and 12 soil samples from the Muli, Jiangcang, and Mole basins to estimate the chemical component concentrations and to analyze hydrochemical characteristics, distribution patterns, and origins in this coal mining-affected river basin. Coal mining has enhanced the weathering of the lithosphere in the study region. The total dissolved solids in the river range from 145.4 to 701.9 mg/L, which is higher than the global average for rivers. Ion concentration spatial distributions increase around mining areas. River geochemistry is mainly controlled by coal mining activity, carbonate weathering, and silicate weathering, with variances of 33.4%, 26.2%, and 21.3%, respectively. Ca2+, Mg2+, and HCO3? are mainly due to the dissolution of carbonate minerals (calcite > dolomite); Si and K+ are mainly from potassium (sodium) feldspar weathering; and Na+ and SO42? mainly from coal mine production. A conceptual model of the river water ion origins from the study area is presented and management implications for improving the adverse effects of coal mining are proposed. These results provide an important standard reference for water resource and environmental management in the study region.

摘要:The Upper Shihezi sedimentary rocks in the Linxing region has been estimated with a significant volume of tight sandstone gas. However, lateral distribution of the present-day stress magnitude is poorly understood, which limits further gas production. Hence, a one-dimensional mechanical earth model and a three-dimensional heterogeneous geomechanical model are built to address this issue. The results indicate that the strike-slip stress regime is dominant in the Upper Shihezi Formation. Relatively low stresses are mainly located around wells L-60, L-22, L-40, L-90, etc, and stress distributions exhibit the similarity in the Members H2 and H4. The differential stresses are relatively low in the Upper Shihezi Formation, suggesting that complex hydraulic fracture networks may be produced. Natural fractures in the Upper Shihezi Formation contribute little to the overall gas production in the Linxing region. In addition, the minimum principal stress gradient increases with Young’s modulus, suggesting that the stiffer rocks commonly convey higher stress magnitudes. There is a strong interplay between stress distribution and heterogeneity in rock mechanics. Overall, the relative error between the predicted and measured results is less than 10%, implying that the predicted stress distribution is reliable and can be used for subsequent analysis in the Linxing region.

摘要:The P-wave velocity structure in the shallow crust is investigated in and around the Sulu-Dabie region by using seismic reflection data for deep soundings in 48 survey profiles and from rock velocity determinations. The observed velocity distributions show obvious heterogeneities in this region. The low velocity anomalies are observed mainly in the west of the Dabie region and the East Sea regions. The high velocity anomalies emerge in the shallow crust of the Sulu and Dabie orogeny. These high-velocity anomalies can be attributed to the ultra-high pressure metamorphosed (UHPM) rock formed by exhumation motion of mantle materials during the orogeny. The high-velocity anomalies in the different shallow layers beneath the Sulu region are located to the northeast of the Tan-Lu fault. The high-velocity anomalies beneath the Dabie region are located southwest of the Tan-Lu fault. Such a distribution pattern of velocity anomaly zones may reveal historical motion of a left-lateral strike-slip for the Tan-Lu fault, which differs from the result of a right-lateral strike-slip motion regime known from modern seismology, indicating a more complex tectonic motion along the Tan-Lu fault.

摘要:The salinity of the salt lake is an important factor to evaluate whether it contains some mineral resources or not, the fault buried in the salt lake could control the abundance of the salinity. Therefore, it is of great geological importance to identify the fault buried in the salt lake. Taking the Gasikule Salt Lake in China for example, the paper established a new method to identify the fault buried in the salt lake based on the multi-source remote sensing data including Landsat TM, SPOT-5 and ASTER data. It includes the acquisition and selection of the multi-source remote sensing data, data preprocessing, lake waterfront extraction, spectrum extraction of brine with different salinity, salinity index construction, salinity separation, analysis of the abnormal salinity and identification of the fault buried in salt lake, temperature inversion of brine and the fault verification. As a result, the study identified an important fault buried in the east of the Gasikule Salt Lake that controls the highest salinity abnormal. Because the level of the salinity is positively correlated to the mineral abundance, the result provides the important reference to identify the water body rich in mineral resources in the salt lake.

摘要:Trapped ancient microorganisms in halite fluid inclusions are of special interest to the understanding of biology and ecology in salt lake systems. With the integration of petrologic, microthermometric, and Raman spectroscopic analyses, this study utilizes fluid inclusions from Chaka Salt Lake, eastern Qaidam Basin, NW China, to assess the possibility of microorganism-trapping by fluid inclusions. Here, we report that the solid phase of some primary fluid inclusions contains carotenoids, which is interpreted as evidence of Dunaliella algae, and that the coexisting liquid phase comprises SO42?. The homogenization temperatures of single-phase primary fluid inclusions indicate that the precipitation temperature of the Holocene halite in Chaka Salt Lake ranges from 13.5°C to 36.4°C. This suggests that fluid inclusions in halite are a good medium for trapping and preserving ancient microorganisms and organic matter in salt lakes, and that Raman spectroscopy has good potential to identify halophilic archaea.

摘要:Based on the requirement of the new technology for producing potassium sulfate and N-Mg compound fertilizer, boussingaultite, by the reaction of the mineral shoenite from Kunteyi Salt Lake, Qinghai province, and the industrial by-product ammonium sulfate, the solubilities of the quaternary system (NH4)2SO4-MgSO4-K2SO4-H2O at 25.0oC in the isothermal evaporation and crystallization process were measured using the isothermal evaporation method, and the corresponding phase diagrams were plotted. According to the diagram, this system contains six saturation points and six solid phase fields of crystallization, which correspond to (K1-m,(NH4)m)2SO4, (NH4)2SO4·MgSO4·6H2O, K2SO4·MgSO4·6H2O, MgSO4·6H2O, (K1-n,(NH4)n)2SO4·MgSO4·6H2O and MgSO4·7H2O, respectively. By analyzing and calculating the isothermal evaporation and dissolution phase diagram of this quaternary system at 25.0oC, K2SO4 and (NH4)2SO4·MgSO4·6H2O can be separated via K2SO4·MgSO4·6H2O and (NH4)2SO4 as raw materials. Theoretical calculations about the proposed process were carried out and verified by experiment, which indicated that the yield of potassium sulfate was improved and the magnesium resources were fully utilized.

摘要:The methods of deriving FeO and TiO2 contents from the Clementine spacecraft data were discussed, and an approach was developed to derive the content from the measurements using the Moon Mineralogy Mapper (M3) instrument on Chandrayaan-1. The density of lunar bedrock was then modeled on the basis of the derived FeO and TiO2 abundances. The FeO and TiO2 abundances derived from the M3 data were compared with the previous results of the Clementine data and were in good agreement. The FeO abundance data also agreed well with the Lunar Prospector data, which were used as an independent source. The previous Clementine and newly M3 derived abundances were compared with the laboratory measured FeO and TiO2 contents in the Apollo and Luna returned samples. The Clementine derived FeO content was systematically 1%–2% lower than the laboratory measurements in all the returned samples. The M3 derived content agreed well with the returned Apollo samples and was within ±2.8% of the laboratory measurements. The Clementine derived TiO2 abundance was systematically 0.1%–4% higher than the laboratory measurements of the returned samples. The M3 derived TiO2 agreed well (±0.6%) with the laboratory measurements of the returned samples, except for samples with high TiO2 content. However, these results should be carefully interpreted because the error range requires verification. No error analysis was provided with the previous Clementine derived contents.

摘要:Intrusion-related gold deposits (IRGDs) occur in the Eastern Desert (ED) of Egypt within magmatic districts that are exploited for tungsten and tin mineralization. IRGDs and intrusion-related rare metal deposits (IRRMDs) are almost invariably linked with the late to post collisional Younger Granites (YGs) that have three successive phases (I, II and III). At ~635–630 Ma, the ED underwent a transition in deformation style from compressional to extensional and a switch from subduction with crustal thickening to delamination with crustal thinning. This transition was concurrent with the emplacement of a short magmatic pulse (~635–630 Ma) that represents a transition between orogenic gold deposits and IRGDs. K-rich calc alkaline granites (phase I and II of the YGs) hosting IRGDs like the Hangalia deposit were emplaced during the time span 630–610 Ma. Alkaline magmatism began at 610 Ma, coexisting with the K-rich calc-alkaline magmatism over the 610–590 Ma time span, where the Fawakhir (598 ± 3 Ma) and Um Had (596 ± 2 Ma) granites that host the IRGDs were emplaced. In time, the alkaline magmatism became more alkaline giving rise to phase III of the YGs that hosts IRRMDs. A distinct metallogenic epoch comprising both IRGDs and IRRMDs, was undergoing extreme growth at ~600 Ma.

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