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The Qiangtang Basin is one of the largest Mesozoic petroliferous basins in China that is still unexploited for the petroleum industry. The basic geological issues and synthesis of the Qiangtang Basin related to the Tethyan evolution are still poorly understood. This volume presents 20 research papers to address the tectonic settings, basin evolution, and sedimentary environments of the Qiangtang Basin, which are key factors for a better understanding of the overall petroleum system. The Qiangtang Basin holds a Precambrian base developed in response to the Paleo-Tethys Hol Xil-Jinshajiang Ocean evolution, with enhanced sedimentary basin infilling during the opening and expansion of the Neo-Tethys Bangong-Nujiang Ocean in the Mesozoic. The Paleozoic basin framework of the Qiangtang demised as the Paleo-Tethys Ocean closed at the latest Permian, while the Early-Middle Triassic foreland basin underwent a negative basin inversion during the Late Triassic. The latter initiated a new sedimentary filling cycle of the Qiangtang Basin, which was triggered by the active extensional rifting and the onset of the bimodal volcanic eruption. Recent scientific exploratory drilling (QK-1 well) found that the Qiangtang Basin is characterized by multiple source rocks, of which the upper Triassic Bagong Formation and the lower Quse Formation exhibit the most hydrocarbon generation potential. The development of high quality and quantity source rocks in the Qiangtang Basin is ensured by regional to global-scale bottom-water anoxia and high primary productivity in the eastern Tethys realm in the Late Triassic and the Early Jurassic. The main reservoirs in the Qiangtang Basin include the Middle Jurassic reef-beach facies, the Upper Triassic carbonates, and the Lower Jurassic terrestrial clastic rocks. Two very-thick caprocks of gypsum in the Lower Jurassic and gypsum mudstones in the Middle Jurassic strata are found during the scientific drilling, which is interpreted as favorable regional-scale seals for petroleum entrapment in the Qiangtang Basin. [ABSTRACT FROM AUTHOR]

• The accretionary complexes in the CAOB contain seamount fragments. • The pillow basalts in accretionary complexes show typical OIB affinity. • The stratigraphic framework of seamount was preliminarily reconstructed in Paleo-Asian Ocean. • A multiple intra-oceanic arc with seamount subduction and accretion model is proposed for the CAOB. The Central Asian Orogenic Belt (CAOB) is one of the largest and long-lived accretionary collages worldwide, and provides an ideal opportunity to address the fundamental geological processes and continental growth of accretionary orogens. However, the tectonic history of the CAOB is still controversial. Previous studies mainly focused on the process and model of accretion and subduction, but did not pay much attention to oceanic intraplate volcanoes. In this paper, we provide an overview of the salient features of twelve OIB-hosting accretionary complexes with ages from Late Neoproterozoic to Early Carboniferous in western the CAOB, and distinguish rock association of typical seamounts from accretionary complexes and shear zones, including pillow basalt, volcanic breccia, limestone, olistostromes and terrestrial clastic rocks. Combined with unique structural features of seamount, the stratigraphic framework of seamount was preliminarily reconstructed in Paleo-Asian Ocean, but the distribution and scale of seamounts is still not clear. Geochemically, volcanic rocks from seamounts are mainly alkaline basalts with litte tholeiitic basalts. The alkaline basalts are characterized by LREE enrichment and HREE depletion, and no obvious Nb, Ta and Ti negative anomalies, suggesting typical OIB affinity. The Nd, Sr and Pb isotopic features indicate that magma sources have enriched components and show fluid metasomatism. In short, this is consistent with geochemical features of Louisville, Ontong Java and Hawaiian seamounts which are related to mantle plumes, but do not contain high-Mg picrite and komatitic basalt. Based on our observations, and in combination with previous work, we present an innovative model in which the CAOB was involved multiple intra-oceanic arc with seamounts subduction and accretion, which is similar to the present-day Pacific and can better explain the tectonic evolution of the CAOB. However, further studies are needed to document the distribution, scale and mantle dynamics of seamounts in the CAOB. [ABSTRACT FROM AUTHOR]

[Display omitted] • Sedimentary provenances in the North Yellow Sea Basin changed in the Middle Jurassic – Early Cretaceous. • The change of sedimentary provenance was associated with the transition from compressive to extensional tectonic setting. • The transformation of tectonic regime was completed in the Early Cretaceous. During the Mesozoic, the Eastern North China Craton experienced a transformation from the compressive to extensional tectonic setting. The Middle Jurassic-Lower Cretaceous sedimentary rocks of the North Yellow Sea Basin in the Eastern North China Craton may contain information about possible changes of sources of sediments. Based on the detrital zircon U-Pb ages of sedimentary rocks and the statistics of detritus of clastic rocks, this paper deal with the provenances of these rocks from the Middle Jurassic-Early Cretaceous in the North Yellow Sea Basin. The Middle Jurassic detritus of clastic rocks were from the basement of the basin and the Sulu Orogenic Belt in the Jiaodong Peninsula. In the Late Jurassic, the detrital particles from the Jiaobei Uplift and Sulu Orogenic Belt increased, and the detritus of clastic rocks from the Liaodong Peninsula also flowed into the basin. In the Early Cretaceous, the detritus of clastic rocks from the Jiaodong Peninsula decreased, while detritus of clastic rocks from the Liaodong Peninsula dominated. The provenances of the Middle-Upper Jurassic sedimentary rocks in the basin were controlled by multiple directions, while the provenance of the Lower Cretaceous sedimentary rocks changed from multiple directions to single direction. Obviously, with the passage of time (from Middle Jurassic to Early Cretaceous), the spatial transformation of the provenances in the North Yellow Sea Basin was a response to the transformation of regional tectonic setting. In the Early Cretaceous, the Eastern North China Craton completed transformation from the Paleo-Asian tectonic domain to the marginal Pacific tectonic domain. [ABSTRACT FROM AUTHOR]

[Display omitted] • Late Neoproterozoic ophiolite fragments were discovered in the Irshi area. • The early Paleozoic crust of the middle Great Xing'an Range is an orogenic belt. • Neoproterozoic–early Paleozoic lateral crustal growth occurred in the eastern CAOB. The tectonic affinity of the middle segment of the Great Xing'an Range (GXR) in NE China has become one of the focus issues about the Paleozoic crustal division and tectonic evolution of the eastern segment of the Central Asian Orogenic Belt. In this paper, we identified some ophiolite fragments from the early Paleozoic strata in the Irshi area of the middle segment of the GXR, which was previously thought to be the interior of the Precambrian Xing'an block. These ophiolite fragments and the surrounding deformed clastic rocks together constitute the Irshi ophiolite mélange (IOM). Zircon U-Pb dating reveals that the ophiolites formed during 603–608 Ma, which indicates that there was an oceanic basin during the late Neoproterozoic. The geochemical composition suggests that the ophiolites were formed in a back-arc setting. The youngest group of detrital zircons in the matrix ranges from 435 Ma to 480 Ma. In addition, the IOM was covered unconformably by late Silurian and Devonian strata, and it was thus likely emplaced during the early–middle Silurian. The identification of the IOM eliminated the possibility that the middle segment of the GXR was an independent Precambrian continental block. The spatial–temporal distribution of Proterozoic–early Paleozoic ophiolite, metamorphic complexes, and magmatic and sedimentary rocks in the middle segments of the GXR indicates that the tectonic affinity of the late Neoproterozoic–early Paleozoic crust in this area is an accretionary orogenic belt. The continuous subduction of the Paleo-Asian Ocean was responsible for the formation of the orogenic belt. [ABSTRACT FROM AUTHOR]

• Early Silurian clastic rocks were deposited in a passive margin setting. • Sediments were sourced from the interior of the SCB and the Northern East Gondwana. • Xuefeng Uplift underwent rapid uplift and erosion during the Early Silurian. • Xuefeng Uplift was an intraplate basement uplift affected by the Kwangsian Orogeny. Xuefeng Uplift is located on the southeast Upper Yangtze region, west of the Cathaysia. Clastic rocks in the Early Silurian Xiaoheba Formation were deposited on northwest flank of the Xuefeng Uplift. Provenance of these clastic rocks may record the Early Silurian tectonic evolution of the Xuefeng Uplift. In this paper, we present whole-rock geochemical data and detrital zircon U–Pb ages for the Xiaoheba Formation. Geochemical signatures suggest that the Early Silurian clastic rocks were deposited in a passive margin and mainly derived from felsic igneous rocks and recycled sedimentary rocks. Two major age populations of 1000–900 Ma and 900–700 Ma, as well as four minor populations, were identified. Our data suggest that the Cathaysia, especially the Wuyi–Yunkai domains, experienced intensive uplift in the Early Silurian, resulting in numerous recycled detritus (1000–900 Ma) supplied to the study area crossed through the Xuefeng Uplift. Meanwhile, age population of 900–700 Ma suggests that the Xuefeng Uplift was an additional source for the Xiaoheba Formation, indicating the uplift had already formed in the Early Silurian. Based on aforementioned evidence and published data, we consider that the formation of Xuefeng Uplift is associated with the Early Paleozoic intraplate orogenesis. The Xuefeng Uplift may have partly uplifted above sea level in this period, but it did not obstruct sediments derived from the Cathaysia. The youngest age cluster of zircons is 436 ± 5.7 Ma, indicating the maximum deposition age of the Xiaoheba Formation and implying the initial formation time of the uplift is roughly in the Early Telychian. [ABSTRACT FROM AUTHOR]

[Display omitted] • Grenville-age terrane is identified in the Qilian orogen. • The Precambrian basement of the Qilian orogen is divided into four distinct mega-sequences. • ∼475 Ma metamorphism was related to the subduction of the Proto-Tethys Ocean. The Qilian orogen at the northeastern margin of the Tibetan Plateau records a complete history from continental breakup to oceanic basin evolution and back to continental collision during the Neoproterozoic to Paleozoic interval. The Qilian Ocean, as a branch of the Proto-Tethys Ocean, was connected to the Iapetus Ocean but is lesser known than its two more famous counterparts. This paper presents zircon U-Pb and biotite-muscovite 40Ar/39Ar isotope data from the Yemananshan Complex in the western Central Qilian belt to assess the age and provenance of late Mesoproterozoic-early Paleozoic successions in the Qilian orogen. The results indicate the Central Qilian belt is characterized by Late Mesoproterozoic-early Neoproterozoic orogenesis with magmatism from 1200 Ma to 900 Ma and clastic metasedimentary rocks deposited between 1050 and 920 Ma. Statistical analysis of detrital zircon data and auxiliary temporal information from the Qilian orogen affirms the notion that sedimentation occurred in four distinct megasequences: (1) 1950–1850 Ma, the oldest known strata, (2) 1250–920 Ma, during Grenvillian-Sveconorwegian orogenesis, (3) 840–760 Ma, the disintegration of Rodinia, and (4) 650–550 Ma, which is typical of the orogenic belts that sutured the Gondwana continental blocks. Metamorphic zircon and 40Ar/39Ar isotope data indicate early Paleozoic metamorphism at ca. 475 Ma, which overlaps with magmatic activity associated with arc-back-arc basin development in the Central Qilian belt, which was associated with subduction of the Proto-Tethys in eastern Gondwana. [ABSTRACT FROM AUTHOR]

[Display omitted] • The western Ordos Basin has excellent potential to form sandstone-type uranium deposits. • The search for uranium reservoirs should focus on the northwest of the Ordos Basin. • Regions where intermediate-acid rocks are present are ideal targets for uranium exploration. • Tracking along the provenance supply direction is an effective method for uranium exploration. The Middle Jurassic Zhiluo Formation is the main uranium-bearing sequence in the western Ordos Basin, northern China. Provenance studies of clastic rocks in the Zhiluo Formation are important to provide guidelines for uranium exploration. In this paper, we describe the sandstones from the Zhiluo Formation and report their bulk rock elemental compositions by using samples that were collected from the Lingwu area, western Ordos Basin. Our main objective is to provide constraints on the provenance of the sandstones and thus new insights into uranium exploration. The results show that the sources of the Zhiluo Formation sandstones have TTG (trondhjemite-tonalite-granodiorite) attributes and mainly consist of magmatic arc orogenic belts that were mixed with continental blocks and recycled orogenic belt materials. The paleocurrent measurements that average 144° suggest that the provenance supply direction of the sandstones is from northwest to southeast. Combined with the regional tectonic settings, it can be inferred that the sandstone provenance was mainly provided by the Xingmeng Orogenic Belt, while the Alxa Block and Helan Mountain complex rocks also contributed. Our research might provide a crucial reference for predicting the locations of potential uranium reservoirs, i.e., the search for uranium mineralization should target the northwest of the Ordos Basin, especially near regions where intermediate-acid rocks are present. This information is integrated into a predictive model in which tracking along the provenance supply directions of clastic sediments is an efficient method for conducting uranium exploration in a sedimentary basin. [ABSTRACT FROM AUTHOR]

Abstract: Geochemical studies done on the Baguio Mineral District had dominantly looked at the igneous rocks. A major gap is the scarcity of studies dealing with the sedimentary rock geochemistry for this district which this paper intends to address. The petrographic data and major and trace element compositions of the siltstones–sandstones from the lower member of the Late Oligocene to Early Miocene Zigzag Formation show that they are generally quartz-rich and have high K2O, Th and La/Sc contents. The chondrite-normalized REE pattern exhibits a negative Eu anomaly, enrichment in LREEs and flat HREEs similar to typical post-Archean shales. Taken together, the data indicate derivation of the lower member of the Zigzag Formation from intermediate to acid igneous rock sources generated in an active margin setting. A likely candidate source is the Cordon Syenite Complex/Palali Formation in the Northern Sierra Madre – Caraballo Mountains. Derivation from mafic source rocks in an oceanic island arc setting is inferred for samples of the Middle to Late Miocene Klondyke, Late Miocene to Early Pliocene Amlang and Late Pliocene Cataguintingan Formations. These samples are characterized by low K2O, Th and La/Sc but high Cr/Th values. Unroofing of the Pugo Metavolcanics and the younger plutons in the Central Cordillera provided the materials which eventually produced the Klondyke and Amlang Formations. Continuous uplift and shallowing of the basin resulted in the deposition of the Cataguintingan Formation. The petrography, geochemistry and geological features of the sedimentary rocks clearly define the change in sediment provenance from quartz-rich during the Oligocene to quartz-deficit in the Miocene. This offers additional constraints in understanding the geological evolution of the mineral district. [Copyright &y& Elsevier]

[Display omitted] • The Late Cretaceous clastics in the Shoushan Basin are divided into five microfacies. • The microfacies heterogeneity is due to the differential implication of the diagenetic factors. • These rocks are divided into some reservoir rock types to get a more accurate reservoir modelling. • The very fine massive sandstone microfacies has the best reservoir quality due to its dissolution. • The laminated siltstone and the bioturbated limestone are highly cemented by silica cement. The Late Cretaceous Upper Bahariya Member is one of the most prolific reservoir sequences in the North Western Desert of Egypt. In this paper, we describe core samples of the Upper Bahariya Member, including core photos, conventional core analysis, petrographical description, scanning electron microscope images, and XRD analysis. Samples for this study are from the reservoir sequence in four wells selected from the Shurouk Field in the Shoushan Basin to delineate the impact of the constraint mineral composition on the reservoir quality. The objective of this study is to get an accurate reservoir characterization of this reservoir by applying the rock typing technique to the studied sequence where four Lithofacies Associations (LFA1, LFA2, LFA3, and LFA4) and four corresponding Reservoir Rock Types (RRT1, RRT2, RRT3, and RRT4) were assigned. These are defined as 1) very fine massive sandstone (LFA1, RRT1), 2) laminated, cross-bedded and bioturbated sandstone (LFA2, RRT2), 3) laminated, highly argillaceous and ferruginated sandstone and siltstone (LFA3, RRT3), and 4) laminated and ferruginated siltstone and well cemented bioturbated limestone (LFA4, RRT4). Petrographically, these lithofacies were categorized into five microfacies; 1) glauconitic quartz arenite, 2) subfeldspathic arenite, 3) glauconitic sublithic arenite, 4) ferruginated subfeldspathic wackes, and 5) sandy fossiliferous packstone microfacies. Conventional core samples include bulk and grain densities (ρ b and ρ g , respectively), helium porosity (∅ He), and horizontal and vertical permeabilities (k H and k V , respectively). The application of the Dykstra-Parsons technique to the available permeability data indicates that the studied sequence is extremely heterogeneous (heterogeneity factor (V) = 0.90). Based on the available samples, the normalized porosity index (∅z), reservoir quality index (RQI), flow zone indicator (FZI), and the discrete rock type values (DRT) were estimated to determine the reservoir quality. The RRT1 samples are characterized by the best reservoir properties (av. ∅ He = 14.7%, av. k H 42.0 = md, av. RQI = 0.47 µm, av. FZI = 2.87 µm, and av. DRT = 13), whereas the lowest reservoir quality is assigned to the RRT4 samples (av. ∅ He = 18.8%, av. k H 0.30 = md, av. FZI = 0.15 µm, av. RQI = 0.04 µm, and av. DRT = 7). The low reservoir quality of the RRT4 is primarily attributed to the predominance of lower quality features (compaction effect, cementation, and presence of glauconite and authigenic minerals). Following the Improved Stratigraphic Modified Lorenz (ISML plot), the Upper Bahariya reservoir is subdivided into five Hydraulic Flow Units (HFUs) such as the HFU-2, and the HFU-4 that are considered superconductive flow units that alternate with three poorly hydraulic conductive HFUs (HFU-1, HFU-3, and HFU-5). The present integrated sedimentological and petrophysical workflow is considered a significant study of the Shoushan basin which can improve exploration activities as well as production optimization. In addition, dividing the studied clastic sequence into five microfacies association and four reservoir rock types can be extended to other equivalent subsurface Late Cretaceous clastic sedimentary rocks in the vicinity and other basins. [ABSTRACT FROM AUTHOR]