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The flat-slab subduction model has been proposed to explain the complex Mesozoic–Cenozoic geotectonic record of SE China as part of the Western Pacific margin. Here we investigate the post-250 Ma thermal history of the Shaoguan-Longnan region to evaluate the time-temperature evolution of local sedimentary and magmatic rocks in the context of the flat-subduction model. Our multi-chronological approach includes zircon U-Pb geochronology, 40Ar/39Ar dating of K-feldspar and biotite, (U-Th)/He dating of zircon and apatite, and fission-track dating of apatite from basement and/or sedimentary rocks, as well as vitrinite reflectance analysis of coal seams. Zircon U-Pb dating revealed Early Silurian and Late Jurassic crystallization ages for the Fuxi (ca. 438 Ma) and Liyuan (ca. 162 Ma) granites, respectively. Syn-/pre-depositional single-grain zircon (U-Th)/He ages from Lower Jurassic sandstones record a Middle Triassic exhumational cooling, interpreted to reflect the Indosinian Orogeny, possibly caused by a flat-slab subduction event. Late Jurassic biotite 40Ar/39Ar age (ca. 156 Ma) obtained from the Late Triassic Mengdong granite, together with maximum vitrinite reflectance values of 1.7%–2.3% measured from a Lower Jurassic coal sample, document a thermal maximum in the Late Jurassic, likely related to the prior regional magmatism arising from delamination of the subducting Paleo-Pacific plate. K-feldspar 40Ar/39Ar plateau age from the Fuxi granite (ca. 125 Ma), and zircon (U-Th)/He mean ages (152–115 Ma) record a protracted cooling through the K-feldspar Ar and the zircon He partial retention zones during the Cretaceous. The Cretaceous cooling is in accord with the prediction of regional uplift and erosion in response to foundering of the flat-slab and consequent lithospheric rebound. The rapid cooling during the Paleocene–Eocene, recorded by apatite fission-track central ages (72–39 Ma) and apatite (U-Th)/He mean ages (38–33 Ma), is interpreted to reflect Cenozoic rifting in the leadup to the opening of the South China Sea.

Optimization of island microgrids should configure the module type and size in such a way that multiple objectives can be balanced. This paper presents a bioinspired optimization approach of microgrid sizing, with two salient features. First, the multiple objectives are categorized into four types: reliability, economy, renewable technology, and pollution. We present a triangular aggregation model, which is straightforward and cost effective to compute the fitness. Second, a bioinspired algorithm named Levy-Harmony is developed. We embed the Levy flight into the Harmony vector updating to enhance the global searching ability and, meantime, adopt a bias factor to avoid unnecessary exploration. The searching speed and accuracy are well balanced and improved. The real datasets are used for comparative studies, demonstrating the superiority of the proposed scheme against typical existing approaches.

Differential tectonothermal evolutionary history of the southern part of the Western Ordos Basin, the southern part of the Liupanshan Mountains, and the northwestern part of the Weibei Uplift was revealed since Late Jurassic by integrating low-temperature thermochronology of apatite fission-track, apatite (U-Th-Sm)/He and zircon (U-Th)/He along with vitrinite reflectance. Inverse modeling results suggest four cooling stages among these three regions since Late Jurassic. Uplift-cooling in the Southwestern Ordos Basin commenced simultaneously with that in the South Liupanshan Mountains in Late Jurassic at ~164–160 Ma. During Late Cretaceous, the entire southwestern region uplifted and cooled since ~118 Ma in the Southwestern Ordos Basin and in the Northwest Weibei Uplift, and since ~105 Ma in the South Liupanshan Mountains. During Early Cenozoic, the Southwestern Ordos Basin and the Northwest Weibei Uplift continued uplift-cooling, while parts of the South Liupanshan Mountains subsided. Since Miocene, a rapid uplift-cooling event of the South Liupanshan Mountains commenced at ~24 Ma, and at ~8 Ma for the Southwestern Ordos Basin and the Northwest Weibei Uplift. In general, the differential evolutionary process of the southwestern North China Plate began in Late Jurassic, continued in Cretaceous and reaching a cooling peak during Miocene with heterogeneous start-time and cooling rate of different sub-units, and mainly controlled by the regional uplift-cooling event of the Qinling-Qilian Orogen in Late Jurassic - Early Cretaceous and by the Qinghai-Tibet Plateau event since Paleocene.

Field investigation combined with detailed petrographic observation indicate that abundant oil, gas, and solid bitumen inclusions were entrapped in veins and cements of sedimentary rocks in the Dabashan foreland, which were used to reconstruct the oil and gas migration history in the context of tectonic evolution. Three stages of veins were recognized and related to the collision between the North China block and the Yangtze block during the Indosinian orogeny from Late Triassic to Early Jurassic (D1), the southwest thrusting of the Qinling erogenic belt towards the Sichuan basin during the Yanshanian orogeny from Late Jurassic to Early Cretaceous (D2), and extensional tectonics during Late Cretaceous to Paleogene (D3), respectively. The occurrences of hydrocarbon inclusions in these veins and their homogenization temperatures suggest that oil was generated in the early stage of tectonic evolution, and gas was generated later, whereas solid bitumen was the result of pyrolysis of previously accumulated hydrocarbons. Three stages of hydrocarbon fluid inclusions were also identified in cements of carbonates and sandstones of gas beds in the Dabashan foreland belt and the Dabashan foreland depression (northeastern Sichuan basin), which recorded oil/gas formation, migration, accumulation and destruction of paleo-reservoirs during the D2. Isotopic analysis of hydrocarbon fluid inclusions contained in vein minerals shows that δ13C1 of gas in fluid inclusions ranges from –17.0‰ to –30.4‰ (PDB) and δD from –107.7‰ to –156.7‰ (SMOW), which indicates that the gas captured in the veins was migrated natural gas which may be correlated with gas from the gas-fields in northern Sichuan basin. Organic geochemical comparison between bitumen and potential source rocks indicates that the Lower Cambrian black shale and the Lower Permian black limestone were the most possible source rocks of the bitumen. Combined with tectonic evolution history of the Dabashan foreland, the results of this study suggest that oil was generated from the Paleozoic source rocks in the Dabashan area under normal burial thermal conditions before Indosinian tectonics and accumulated to form paleo-reservoirs during Indosinian collision between the North China block and the Yangtz block. The paleo-reservoirs were destroyed during the Yanshanian tectonic movement when the Dabashan foreland was formed. At the same time, oil in the paleo-reservoirs in the Dabashan foreland depression was pyrolyzed to transform to dry gas and the residues became solid bitumen.

Natural bitumen is the evolutionary residue of hydrocarbon of sedimentary organic matter. Several kinds of bitumen with different occurrences, including bitumen in source rock, migration bitumen filled in fault, oil-bed bitumen and paleo-reservoir bitumen, are distributed widely in the Dabashan foreland. These kinds of bitumen represent the process of oil/gas formation, migration and accumulation in the region. Bitumen in source rock filled in fractures and stylolite and experienced deformation simultaneously together with source rock themselves. It indicated that oil/gas generation and expelling from source rock occurred under normal buried thermal conditions during prototype basin evolution stages prior to orogeny. Occurrences of bitumen in source rock indicated that paleoreservoir formation conditions existed in the Dabashan foreland. Migration bitumen being widespread in the fault revealed that the fault was the main channel for oil/gas migration, which occurred synchronously with Jurassic foreland deformation. Oil-bed bitumen was the kind of pyrolysis bitumen that distributed in solution pores of reservoir rock in the Dabashan foreland depression, the northeastern Sichuan Basin. Geochemistry of oil-bed bitumen indicated that natural gas that accumulated in the Dabashan foreland depression formed from liquid hydrocarbon by pyrolysis process. However, paleo-reservior bitumen in the Dabashan forleland was the kind of degradation bitumen that formed from liquid hydrocarbon within the paleo-reservior by oxidation, alteration and other secondary changes due to paleo-reservior damage during tectonics in the Dabashan foreland. In combination with the tectonic evolution of the Dabashan foreland, it is proposed that the oil/gas generated, migrated and accumulated to form the paleo-reservoir during the Triassic Indosinian tectonic movement. Jurassic collision orogeny, the Yanshan tectonic movement, led to intracontinental orogeny of the Dabashan area accompanied by geofluid expelling and paleo-reservoir damage in the Dabashan foreland. The present work proposed that there is liquid hydrocarbon exploration potential in the Dabashan foreland, while there are prospects for the existence of natural gas in the Dabashan foreland depression.

In this study one- (hydrocarbon liquid), two- (hydrocarbon liquid and vapor) and three- (hydrocarbon liquid and vapor, and aqueous liquid) phase fluid inclusions have been investigated in calcites occurring in veinlets in fine grained sandstones of Chang 7 source rock and Chang 8 reservoir rock. These rocks are parts of the Upper Triassic Yangchang Formation in Ordos Basin, Northern China. The hydrocarbon inclusions studied show high variance in vapor-liquid volume ratio at ambient temperature, suggesting a heterogeneous entrapment of vapor and liquid phases those existed before or during formation of the calcite. This is supported by homogenizations happened into both liquid and vapor phase. Homogenization temperatures are ranging between 70 and 120 °C. We consider that this wide range are rather resulted in heterogeneous entrapment of immiscible liquid and vapor phases than high temperature (e.g., 120 °C) formation of the hydrocarbon inclusions. Therefore, the lower range of homogenization temperatures (around 80 °C) seem to be probable for formation of the hydrocarbon inclusions studied. Fluorescent microscopic results on the hydrocarbon inclusions show bright yellow color for the oil. Fluorescence spectra indexes indicate that oil in the inclusions is quite mature, similarly to the oil extract from Chang 7 source rock. The differences in fluorescent spectra among the hydrocarbon inclusions suggest their chemical modification during evolution, which might be determined by continuous separation of vapor phase (gas condensate) from the system. On the basis of organic geochemistry of the studied samples (e.g., akin distribution of normal-alkanes and similar isoprenoid ratios), it can be concluded that the oil in the inclusions and the crude oil from the reservoir rock Chang 8 are actually derived from the Chang 7 source rock. During tectonic evolution, the hydrocarbon might suffer phase separation (boiling) forming two phases (a liquid and a vapor phase) due to intensive uplifting of Ordos Basin after the Late Cretaceous. The boiling in the accumulated hydrocarbon could result in overpressure in the source rock. This phenomenon might favor formation of fractures and migration of hydrocarbons from their source toward into sandstone reservoirs. Our study demonstrates the significance of detailed analytical investigation of hydrocarbon inclusions in correlation with their potential source rock.

The Dongsheng uranium deposit, localized in the northern Ordos Basin in northern Central China, is among the largest deposits of thistype in China. It occurs in the sandstones of the Middle Jurassic Zhiluo Formation. The crystalline rocks of the Yinshan and Daqingshanorogenic belts in the northern Ordos Basin are the source of uranium for the deposit. The Dongsheng deposit shows the main characteristicsof a sandstone uranium deposit of interstratal oxidation zone, including specific hydrothermal rock alteration. It displays distinct lithologicand mineral zoning. The sandstones of the oxidation zone are variegated and oxidized, and the sandstones of the reduction zone are gray andlight gray medium- to coarse-grained and underwent albitization, carbonatization, chloritization, epidotization, pyritization, etc. Ore-bearingsandstones occur in the transitional oxidation-reduction zone, being confined mainly to the reduction zone. Uranium minerals are predominanthigh-temperature coffinite and subordinate brannerite and uraninite. The homogenization temperature of fluid inclusion in the sandstone cementis 150–160 °C. The performed geological analysis suggests that the hydrothermal alteration of the uranium deposit is intimately related to thesynchronous Mesozoic regional magmatic events in the Ordos Basin.

The western half of the Ordos Basin lies in the north of Central China, on the western margin of the North Chinese Platform. In the southwest and south it borders the Qilian and Qinling folded systems. Their frontal northeastern flank is thrust over the Paleozoic nappe of the Ordos Basin and consists of a series of large parallel linear folds separated by thrusts. The basement of the basin is made up of deformed metamorphic rocks of tentatively Late Proterozoic age. Carbonate and terrigenous intracratonic facies accumulated on the Ordos block from Early Cambrian through Middle Ordovician. From Middle Ordovician through Middle Carboniferous, the western edge of the block was uplifted as a land as a result of Caledonian tectonic movement and underwent denudation for about 150 Myr. In the Late Paleozoic, a series of coal-bearing formations was deposited. In the Triassic, the Ordos Basin became filled with fluviolacustrine delta facies. Thrusts and folds on the southwestern margin of the basin formed in the Mesozoic and were intensified by Himalayan tectonic movements.