• Volume 96,Issue 1,2022 Table of Contents
    Select All
    Display Type: |
    • CONTENTS

      2022, 96(1):0-0.

      Abstract (190) HTML (0) PDF 1.00 M (321) Comment (0) Favorites

      Abstract:

    • SPECIAL PAPER FOR 100th ANNIVERSARY

      2022, 96(1):1-1.

      Abstract (180) HTML (0) PDF 0.00 Byte (0) Comment (0) Favorites

      Abstract:

    • The Centennial Message: Retrospect and Outlook

      2022, 96(1):1-2.

      Abstract (317) HTML (0) PDF 1.96 M (365) Comment (0) Favorites

      Abstract:

    • Hydrodynamic Links between Shallow and Deep Mineralization Systems and Implications for Deep Mineral Exploration

      2022, 96(1):1-25. DOI: 10.1111/1755-6724.14903

      Abstract (402) HTML (0) PDF 4.12 M (528) Comment (0) Favorites

      Abstract:Deep mineral exploration is increasingly important for finding new mineral resources but there are many uncertainties. Understanding the factors controlling the localization of mineralization at depth can reduce the risk in deep mineral exploration. One of the relatively poorly constrained but important factors is the hydrodynamics of mineralization. This paper reviews the principles of hydrodynamics of mineralization, especially the nature of relationships between mineralization and structures, and their applications to various types of mineralization systems in the context of hydrodynamic linkage between shallow and deep parts of the systems. Three categories of mineralization systems were examined, i.e., magmatic-hydrothermal systems, structurally controlled hydrothermal systems with uncertain fluid sources, and hydrothermal systems associated with sedimentary basins. The implications for deep mineral exploration, including potentials for new mineral resources at depth, favorable locations for mineralization, as well as uncertainties, are discussed.

    • Construction of the Continental Asia in Phanerozoic: A Review

      2022, 96(1):26-51. DOI: 10.1111/1755-6724.14867

      Abstract (300) HTML (0) PDF 55.52 M (553) Comment (0) Favorites

      Abstract:This is a review of the formation and tectonic evolution of the continental Asia in Phanerozoic. The continental Asia has formed on the bases of some pre-Cambrian cratons, such as the Siberia, India, Arabia, North China, Tarim, South China, and Indochina, through multi-stage plate convergence and collisional collages in Phanerozoic. The north-central Asia had experienced the expansion and subduction of the Paleo-Asian Ocean (PAO) in the early Paleozoic and the closure of the PAO in the late Paleozoic and early Mesozoic, forming the PAO regime and Central Asian orogenic belt (CAOB). In the core of the CAOB, the Mongol-Okhotsk Ocean (MOO) opened with limited expansion in the Early Permian and finally closed in the Late Jurassic–Early Cretaceous. The south-central Asia had experienced mainly multi-stage oceanic opening, subduction and collision evolution in the Tethys Ocean, forming the Tethys regime and Himalaya-Tibetan orogenic belt. In eastern Asia, the plate subduction and continental margin orogeny on western margin of the Pacific Ocean, forms the West Pacific regime and West Pacific orogenic belt. The PAO, Tethys, and West Pacific regimes, together with Precambrian cratons among or surrounding them, made up the major tectonic and dynamic systems of the continental Asia in Phanerozoic. Major tectonic events, such as the Early Paleozoic Qilian, Uralian, and Dunhuang orogeneses, the late Paleozoic East Junggar, Tianshan and West Junggar orogeneses, the Middle to Late Permian Ailaoshan orogeny and North-South Lhasa collision, the early Mesozoic Indochina-South China and North-South China collisions, the late Mesozoic Mongolia-Okhotsk orogeny, Lhasa-Qiangtang collision, and intra-continental Yanshanian orogeny, and the Cenozoic Indo-Asian, Arab-Asian, and West Pacific margin collisions, constrained the formation and evolution of the continental Asia. The complex dynamic systems have left large number of deformation features, such as large-scale strike-slip faults, thrust-fold systems and extensional detachments on the continental Asia. Based on past tectonics, a future supercontinent, the Ameurasia, is prospected for the development of the Asia in ca. 250 Myr.

    • ORIGINAL ARTICLES

      2022, 96(1):51-51.

      Abstract (116) HTML (0) PDF 0.00 Byte (0) Comment (0) Favorites

      Abstract:

    • Discovery of a New Middle Jurassic Dinosaur Site in Sichuan, China

      2022, 96(1):52-60. DOI: 10.1111/1755-6724.14853

      Abstract (302) HTML (0) PDF 53.11 M (820) Comment (0) Favorites

      Abstract:The Sichuan Basin, also known as the ‘Red Basin’, is famous for its abundance of Mesozoic dinosaur fossils, especially in the Zigong area during the Jurassic era; the Middle Jurassic Shunosaurus and the Late Jurassic Mamenchisaurus faunal assemblages are the most representative. The Qinglongshan dinosaur fossil site is located in Fuxing, to the northwest of Rong County, Zigong City. This new site is situated within the Middle Jurassic Xiashaximiao Formation, and geologically is roughly equivalent to the well-known Dashanpu dinosaur fossil site. More than 600 dinosaur fossils were found concentrated in the excavation area, including teeth; cervical, dorsal and caudal vertebrae; and various parts of appendicular skeletons. This fossil site is also most significant as it provides new information on non-avian dinosaur life during the poorly understood Middle Jurassic.

    • New Discovery of Oligocene Gastropod Opercula from the Yehucheng Formation in Northwestern China

      2022, 96(1):61-70. DOI: 10.1111/1755-6724.14727

      Abstract (171) HTML (0) PDF 3.29 M (251) Comment (0) Favorites

      Abstract:Fourteen species of nonmarine gastropod opercula are found to be in high abundance in the Oligocene upper member of the Yehucheng Formation, Lanzhou Basin, northwest China. They are attributed to two families, namely Bithyniidae and Assimineidae, and four genera, namely Pseudemmericia, Bithynia, Mirolaminatus and Assiminea. Among them, three species are new, and they are Bithynia paramonolithic sp. nov., B. obliquus sp. nov., and B. disregularis sp. nov. Some of these species were first discovered in Paleogene strata of the vast Northwest China and can be compared with the opercula recovered from the Paleogene deposits in East and South China. It is inferred from the paleontology and sediment associations that the climate was slightly humid and the fauna probably inhabited the fresh or brackish water of a shallow lake in the Lanzhou Basin during the late early Oligocene period.

    • Enlightenment of the Mariana Fore-arc Sedimentary Basin Evolution to the Subduction Process

      2022, 96(1):71-80. DOI: 10.1111/1755-6724.14860

      Abstract (223) HTML (0) PDF 88.58 M (421) Comment (0) Favorites

      Abstract:The Mariana subduction structure is a hot topic in ocean-ocean subduction zone research, and its subduction mechanism has attracted wide attention from experts and scholars in China and abroad. Based on the multi-channel seismic data of survey line MGL1204 in the Mariana fore-arc and DSDP ocean drilling data, this paper studies the development and evolution characteristics of the structure and strata in the Cenozoic Mariana fore-arc sedimentary basin. The Cenozoic strata are divided into six seismic sequences, with the possible era of each seismic sequence discerned, and the relationship between fault development and earthquakes analyzed. The episodic activity of the volcanic chain of the Mariana island arc is thought to control the tectonic and stratigraphic development pattern of the Cenozoic sedimentary basin in the fore-arc. Between 16°N–19°N and 146°E–151°E, the maximum thickness of the sedimentary center of the Cenozoic fore-arc sedimentary basin in Mariana is about 2360 m. Normal faults are developed in the area and some broke to the seabed, indicating that the Mariana island arc is still in the post-arc expansion stage. The application of multi-channel seismic sections in structural and stratigraphic evolution study is an important means to elucidating the Mariana subduction mechanism.

    • Final-stage Southward Subduction of the Eastern Paleo-Asian Ocean: Evidence from the Middle Permian Mafic Intrusions in the Northern Margin of the North China Craton

      2022, 96(1):81-99. DOI: 10.1111/1755-6724.14683

      Abstract (182) HTML (0) PDF 7.35 M (278) Comment (0) Favorites

      Abstract:The northern margin of the North China Craton (NCC) contains widespread Permian magmatic rocks, but the origin of these rocks remains controversial. This uncertainty hampers us from better understanding of tectonic framework and evolution of the eastern Paleo-Asian Ocean, particularly with respect to its final-stage subduction and closure time. To address these questions, this study presents petrological, zircon U-Pb geochronological, whole-rock geochemical and in situ zircon Hf isotopic data for these Permian mafic intrusions in the northern margin of the NCC. Precise zircon U-Pb dating results indicate that these mafic intrusions were emplaced in the Middle Permian (ca. 260 Ma). Geochemically, the studied mafic intrusions have high MgO and transition metals element contents, with high Mg# values, indicating a mantle origin. These mafic intrusions are characterized by enrichments in large ion lithophile elements (LILEs; e.g., Rb, Ba, and K) and light rare earth elements (LREEs), and depletions in high field strength elements (HFSEs; e.g., Nb, Ta, and Ti) and heavy rare earth elements (HREEs), indicating that they were formed in a subduction-related setting. These geochemical features, together with zircon εHf(t) values (?1.1 to +11.2), indicate that their parental magmas were derived from partial melting of heterogeneous mantle wedge metasomatized by subduction-related fluids, with the contributions of slab sediments. The studied mafic intrusions also show wide range of major and trace elements contents, and variable Mg# values, Eu and Sr anomalies, suggesting that their parental magmas had undergone variable degrees of fractional crystallization. Together with the E–W trending Permian continental arc along the northern margin of the NCC, we confirm that the generation of the Middle Permian mafic intrusions was related to southward subduction of the Paleo-Asian oceanic lithosphere beneath the NCC and the Paleo-Asian Ocean had not closed prior to the Middle Permian.

    • Upwelling of Mantle-derived Material in Southeast China: Evidence from Noble Gas Isotopes

      2022, 96(1):100-110. DOI: 10.1111/1755-6724.14686

      Abstract (183) HTML (0) PDF 3.82 M (279) Comment (0) Favorites

      Abstract:Shallow groundwater collected in Chaozhou, Huizhou, and Guangzhou allowed testing of concentrations and the isotope ratios of noble gases. Based on the calculated noble gas temperature (NGT) and the ratio of noble gas isotopes, the recharge temperature, recharge source, and residence time of groundwater can be calculated. In addition, the contribution of noble gas components from different sources to the sample components can be assessed. In the Huizhou area, according to the 1/Xe vs. Ne/Xe and NGT data, the shallow sandstone-confined water samples in the Shiba area and the unconfined water samples of the Huangshadong are in different temperature ranges, indicating that they have different recharge sources, both in time or space. The He components in the samples are calculated to obtain the content of radiogenic 4He in the crust and to simulate the groundwater ages. The noble gas isotope ratios show the addition of mantle components into the basalt aquifers and sandstone aquifers in Chaozhou and Huizhou. Except for atmospheric and crustal sources, there is a certain proportion of mantle-derived components in the shallow underground cold water in Huizhou and Chaozhou. The noble gases in the Chaozhou groundwater have an obvious mantle signature, allowing speculation that there is a deep fluid carrying mantle characteristics. This upwelling of mantle-derived material might be caused by the India-Eurasia collision or that between the Philippine Sea Plate and the Eurasian Plate.

    • Melt Pockets in Garnet Megacrysts from Cenozoic Alkali Basalts of the Shavaryn Tsaram Vicinity, Mongolia

      2022, 96(1):111-122. DOI: 10.1111/1755-6724.14768

      Abstract (138) HTML (0) PDF 13.34 M (223) Comment (0) Favorites

      Abstract:Garnet megacryst with a multiphase inclusion from intraplate alkali basalts of the Shavaryn Tsaram (Tariat, Mongolia) was the object of the study. This unusual aggregate consists of porous glass, Ti-rich biotite, orthopyroxene, spinel, clinopyroxene, olivine, and ilmenite. WinTWQ 2.32 thermodynamic simulation of this system revealed a few intervals of equilibrium. Pressure and temperature adjustment reflected in the paragenetic minerals of the melt pocket. The capture of already crystallised garnet megacryst was at P = 0.8–1 GPa and T = 1120–1160°C. Mineral crystallisation inside the melt pocket, accompanied by external inputs, occurred at P = 0.75–0.95 GPa; T = 790–1120°C. Symplectite assemblage formed in the garnet megacryst due to decomposition at (P = 0.55–0.7 GPa; T = 850–930°C). The study of the oxygen isotope content in primary garnet and biotite of the melt pocket showed that the δ18OVSMOW values are the same and correspond to that of typical mantle xenoliths. However, the chemical and microcomponent composition of the melt pocket minerals reveals a material that differs from basalts and peridotites. Thus, it has been revealed that the multiphase inclusion in the garnet megacryst formed not only on account of the garnet's substance, but also due to the entrapped material of the Earth's interior.

    • Geochemical and Boron Isotopic Evidence that Tourmaline Records Country Rock Assimilation of Leucogranites in the Himalayan Orogen

      2022, 96(1):123-134. DOI: 10.1111/1755-6724.14800

      Abstract (171) HTML (0) PDF 64.40 M (442) Comment (0) Favorites

      Abstract:Tourmaline geochemical and boron (B) isotopic compositions in two-mica granites (TMG), tourmaline-bearing leucogranites (Tou-LG), tourmalites and metapelites from the Gyirong–Malashan areas of the Himalayan orogen provide evidence for country rock assimilation during the intrusion of Himalayan leucogranite. The schorls in Gyirong leucogranitic plutons show low contents of MgO (0.238%–1.160%) and δ11B values (?12.1‰–?11.2‰), while dravites gathered in the contact zone between the leucogranitic veins and metapelites show high contents of MgO (4.815%–6.755%) and δ11B values (?10.7‰–?9.3‰). This geochemical and isotopic variation of tourmalines can also be identified in the Malashan gneiss dome. As a result, three types of tourmaline were identified in the Himalayan orogen: (1) Tou-I in the TMG and Tou-LG, which is the most common tourmaline type of schorl; (2) Tou-II (dravite and high-Mg schorl) in the Tou-LG and tourmalite at the margins of the leucogranite; and (3) Tou-III (mainly dravite, with minor high-Mg schorl) in metapelites of the High Himalayan Crystalline Sequence. The lenses and veins of Tou-LG may have experienced metasomatism and assimilation as a result of interaction with the High Himalayan Crystalline Sequence metasedimentary country rocks, which can be traced by the geochemical and isotopic characteristics of the tourmaline therein.

    • U-Pb Geochronology and Geochemistry of Stratiform Garnet from the Aqishan Pb-Zn Deposit, Eastern Tianshan, Xinjiang, NW China: Constraints on Genesis of the Deposit

      2022, 96(1):135-146. DOI: 10.1111/1755-6724.14648

      Abstract (186) HTML (0) PDF 10.30 M (512) Comment (0) Favorites

      Abstract:The Aqishan lead-zinc deposit, located in the Jueluotag metallogenic belt of eastern Tianshan, Xinjiang, Northwest China, has a stratiform occurrence in the marine volcanic tuff of the Yamansu Formation. The ore body has a typical double-layer structure, having a stratified, stratoid, lenticular upper part and a veined, stockwork-like lower part. The occurrence of the upper orebody is consistent with that of the volcanic tuff wall rock. The ore minerals are mainly chalcopyrite, pyrite, sphalerite, galena and magnetite, the altered minerals mainly being silicified, such as sericite, chlorite, epidote, garnet. The garnetized skarn, being stratiform and stratoid, is closely related to the upper part of the orebody. Geological observations show that the limestone in the ore-bearing Yamansu Formation is not marbleized and skarnized. Spatially, it is associated with the ferromanganese deposits in the marine volcanic rocks of the Yamansu Formation. These geological features reflect the likelihood that the Aqishan lead-zinc deposit is a hydrothermal exhalation sedimentary deposit. The results from the EPMA show that the garnet is mainly composed of grossular–andradite series, contents being in a range of 34.791–37.8% SiO2, 32.493–34.274% CaO, 8.454–27.275% FeO, 0.012–15.293% Al2O3, 0.351–1.413% MnO, and lower values of 0.013–1.057% TiO2. The content of SiO2 vs. CaO and FeO vs. Al2O3 has a significant positive correlation. The results of ICP-MS analysis for the garnet show that the REE pattern is oblique to right in general. The total amount of rare earth elements is relatively low, ΣREE = 71.045–826.52 ppm, which is relatively enriched for LREE and depleted for HREE. LREE/HREE = 8.66–4157.75, LaN/YbN = 23.51–984.34, with obvious positive Eu and Ce anomalies (δEu = 2.27–76.15, δCe = 0.94–1.85). This result is similar to the REE characteristics of ore-bearing rhyolite volcanic rocks, showing that the garnet was formed in an oxidizing environment and affected by clear hydrothermal activity. The U-Pb isotopic dating of garnet by fs-LA-HR-ICP-MS gives an age of 316.3 ± 4.4 Ma (MSWD = 1.4), which is consistent with the formation time of the Yamansu Formation. According to the study of deposit characteristics and geochemical characteristics, this study concludes that the Aqishan lead-zinc deposit is a hydrothermal exhalation sedimentary deposit, the garnet being caused by hydrothermal exhalative sedimentation.

    • Biostratigraphy and Sequence Stratigraphy of the Tarbur Formation (Maastrichtian) from Iranian Zagros Foreland Basin, Southwest of Iran

      2022, 96(1):147-166. DOI: 10.1111/1755-6724.14767

      Abstract (173) HTML (0) PDF 19.05 M (421) Comment (0) Favorites

      Abstract:Shallow carbonate deposits (Tarbur Formation) were formed in the Zagros foreland basin with dynamic tectonics during the Maastrichtian age. From the viewpoint of reconstruction of depositional conditions in these deposits, studies of biostratigraphy, microfacies, microtaphofacies, and sequence stratigraphy were performed in a single area at Tang-e Shabi Khoon, northwest of Zagros. Based on the identification of two assemblage zones consisting of benthic foraminifera in these strata, the formation was deposited during the middle to late Maastrichtian. The number of cycles in test size and type of coiling in Loftusia decreased from the study area toward the northwest of the Neotethys basin. The input of clastic sediments affected the distribution of Loftusia and rudists in the study area. Nine microfacies, six microtaphofacies, and one terrigenous facies (shale) were identified based on the sedimentary features. These deposits of the middle-late Maastrichtian were deposited on a homoclinal carbonate ramp. The platform can be divided into restricted and semi-restricted lagoon, shoal, and open marine environments. In the study area, the deposits of the Tarbur Formation were deposited during four third-order depositional sequences. Local fault activities affected the formation of depositional sequences in the study area.

    • Sequence Stratigraphy of the Lower Cretaceous Uraniferous Measures and Mineralization of the Sandstone-hosted Tamusu Large Uranium Deposit, North China

      2022, 96(1):167-192. DOI: 10.1111/1755-6724.14792

      Abstract (281) HTML (0) PDF 45.26 M (423) Comment (0) Favorites

      Abstract:The Bayingobi basin is the Mesozoic–Cenozoic basin in North China in which the Tamusu uranium deposit is located. The ore-target layer of the deposit is the Lower Cretaceous Bayingobi Formation, which developed as a fan delta-shallow lacustrine deposit. The distributary channel sand body of the fan delta plain and the underwater?distributary channel sand body of the fan delta front formed a favorable uranium reservoir, so the study of sequence stratigraphy is extremely important to understanding the genesis of uranium deposits. On the basis of field investigation and a large number of borehole logs, the high resolution sequence stratigraphy of the Lower Cretaceous is divided and the system tracts of different periods are established. The relationship between deposition, interlayer oxidation and uranium enrichment is discussed. The Lower Cretaceous Bayingobi Formation can be divided into two fourth-order sequences (Sq1 and Sq2). The lower member of the Bayingobi Formation is referred to as Sq1, which is composed of a falling-stage system tract (FSST) on top. On the other hand, the upper member of the Bayingobi Formation is referred to as Sq2, which is composed of a lowstand system tract (LST), transgressive system tract (TST) and highstand system tract (HST). The lowstand system tract forms a favorable stratigraphic structure (mud-sand-mud formation) with the lacustrine mudstone of the overlying transgressive system tract, that is conducive for the migration of uranium-bearing oxygen water. The organic matter and pyrite in the fan delta sand body, as well as the dark mudstone in the distributary bay, provided a reducing medium for uranium mineralization. The ore body mainly occurs in the distributary channel, underwater distributary channel or the mouth bar of the fan delta. As a result of the moderate thickness, high permeability, favorable barrier and rich reducing medium, the rich ore body mainly occurs in the underwater distributary channel and mouth bar sand body of the delta front. Based on study of the sequence stratigraphy, the model of the sequence, sedimentation and mineralization of the uranium deposit is established, which enriches uranium metallogenic theory and provides a reference for exploration of the same type of uranium deposits.

    • Provenance of the Early–Middle Devonian Shugouzi Formation in the Quruqtagh, Northeastern Xinjiang: Constraints from Sandstone Geochemistry and Heavy Mineral Analysis

      2022, 96(1):193-207. DOI: 10.1111/1755-6724.14803

      Abstract (158) HTML (0) PDF 10.22 M (393) Comment (0) Favorites

      Abstract:The Early–Middle Devonian Shugouzi Formation in the Quruqtagh block consists?mainly of clastic rocks. However, their provenance has been scarcely studied since it was named. Geochemistry of clastic rocks was commonly used to interpret the provenance. Detrital heavy mineral analyses help frame the U-Pb age from zircon grains, integrated with geochemical data from detrital tourmaline and spinels. These techniques were used to characterize components of the sediment flux and define erosion areas in the Qurugtagh block, further providing evidence about the tectonic evolution of the South Tianshan and Tarim plate. The maximum depositional age constrained by detrital zircon dating was Early–Middle Devonian. Multiple diagrams for sedimentary provenance using major and trace elements indicate that continental island arc-related felsic rocks were the major source rocks for the Shugouzi Formation. Detrital tourmalines are dravite and schorl. The results of detrital tourmaline electron probe microanalysis (EPMA) show that the source rocks are?mainly metasedimentary rocks and granitoids. The detrital chromian spinels within the sediments are characterized by high chroumium (Cr#) and varying magnesium (Mg#). The discrimination plots reveal that these spinels were sourced from island arc magmatic rocks. The laser ablation inductively-coupled plasma mass spectrometry (LA-ICP-MS) U-Pb chronology of detrital zircons suggests that the sediments were derived mainly from 414–491?Ma and 744–996?Ma magmatic rocks. Paleocurrent restoration, sandstone geochemistry, EPMA, and detrital zircon geochronology indicate that the source rocks were predominantly derived from Late Ordovician and Devonian?magmatic rocks and subordinately from recycled Neoproterozoic?magmatic rocks. Comprehensive analyses of the source areas suggest that a remnant arc still existed in the Early Devonian and the Shugouzi Formation was deposited in a passive continental margin.

    • Origin of the Neoproterozoic Baijianshan Banded Iron Formation at the Southeastern Margin of the Tarim Block in NW China: Implication for an Extremely Reducing Ocean

      2022, 96(1):208-220. DOI: 10.1111/1755-6724.14801

      Abstract (173) HTML (0) PDF 10.42 M (481) Comment (0) Favorites

      Abstract:The Neoproterozoic banded iron formations (BIFs) were closely associated with the “Snowball Earth” during the breakup of the Rodinia, thus they played an important role in our understanding of the atmospheric and oceanic oxygen levels during this period. In this contribution, the Neoproterozoic (ca. 737 Ma) Baijianshan BIF at Southeast Tarim, northwestern China was identified. Magnetite is the dominated iron-species, which occurs as the lamina interbedded with chert. The BIF contains low concentrations of trace elements, and is depleted in light rare earth elements (LREEs) based on comparison with the Post-Archean Australian Shale (PAAS). In addition, the BIF exhibits slightly positive La-Eu anomalies, negligible Ce anomalies, insignificant Y anomalies, chondritic Y/Ho ratios (23–32), and slightly chondritic initial εNd (t = 737 Ma) values (?0.45 to 1.46, averaging 0.37). All these features indicate that the precipitation of Baijianshan BIF was closely related to the submarine low-T hydrothermal fluids with little detrital contribution. Moreover, the Baijianshan BIF is characterized by the significant enrichment of heavy Fe isotopes, with δ57FeIRMM-014 values ranging from 1.78‰ to 3.05‰, revealing the partial oxidation of Fe2+ into Fe3+ during the precipitation of this BIF. Our data suggest that the formation of Baijianshan BIF was closely associated with a significantly reducing ocean, which most likely was isolated from the oxidized atmosphere by a local ice sheet. This Neoproterozoic Baijianshan ocean has the initial oxygen levels as low as, or even lower than that of Archean and Paleoproterozoic oceans.

    • Felsic Igneous Rocks in the Hua’aobaote Pb-Zn-Ag Polymetallic Orefield, Southern Great Xing’an Range: Genesis, Metallogenetic and Tectonic Significance

      2022, 96(1):221-239. DOI: 10.1111/1755-6724.14729

      Abstract (178) HTML (0) PDF 17.91 M (271) Comment (0) Favorites

      Abstract:The Hua’aobaote Pb-Zn-Ag Polymetallic orefield is situated in the southern section of the Great Xing’an Range (GXAR), which has experienced extensive magmatism. Since the Paleozoic, there are two stages of magmatism in Hua’aobaote orefield occurred in the Paleozoic and Mesozoic. The Mesozoic magmatism is of great significance for the Pb-Zn-Ag Polymetallic mineralization in Hua’aobaote orefield. In this study, new geochemical data was obtained to discuss the timing and petrogenesis of the magmatic rocks and its geodynamic and metallogenic significance. Zircon U-Pb ages reveal that the felsic igneous rocks from the Hua’aobaote orefield were formed in the Early Permian (294.8 ± 3.2 Ma) and Early Cretaceous (132.6 ± 1.4 Ma). Geochemically, the Early Permian granodiorite porphyrite is characterized by high Sr/Y (42–63) ratios and Mg# (62.24–70.74) values and low heavy rare earth element (HREE) (5.09–6.79 ppm) contents. The granodiorite porphyrite is also characterized by depleted Sr–Nd initial isotopic signatures [εNd(t) = 5.91–7.59, (87Sr/86Sr)i = 0.7029–0.7030], exhibiting adakitic characteristics. The Early Cretaceous granite porphyry and rhyolite are A-type felsic igneous rocks, and demonstrate high SiO2, Na2O + K2O and rare earth element (REE) contents, low CaO and MgO contents, low (87Sr/86Sr)i ratios (0.7044–0.7058), and positive εNd(t) values (2.57–4.65). Whole-rock Pb isotopic compositions in granodiorite porphyrite are: 206Pb/204Pb = 17.631–18.149, 207Pb/204Pb = 15.422–15.450, and 208Pb/204Pb = 37.325–37.729. The granite porphyry and rhyolite have initial 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb ratios of 18.106–19.309, 15.489–15.539, and 37.821–38.05, respectively. Sr-Nd-Pb isotopic evidence suggests that the Early Permian granodiorite porphyrite is likely to derive from slab melts and modified by peridotitic mantle wedge in the subduction tectonic setting of the Paleo-Asian Ocean. The Early Cretaceous A-type felsic igneous rocks were derived from juvenile lower crust, accompanied by limited crustal contamination and various degree of fractional crystallisation during magma emplacement. The Early Cretaceous magmatism and related mineralization were formed in a post-orogenic tectonic setting that attributed to the closure of the Mongol–Okhotsk Ocean. Pb isotopic data for the various rock units in the study area indicate that the Mesozoic magma source contributed substantial Pb, Zn, and Ag to the Hua’aobaote deposit.

    • Syn-mineralization Uplifting and Exhumation of Porphyry Systems in China: Evidence from Fluid Inclusion Data

      2022, 96(1):240-247. DOI: 10.1111/1755-6724.14781

      Abstract (153) HTML (0) PDF 19.24 M (464) Comment (0) Favorites

      Abstract:In order to understand how the metallogenic process of porphyry deposit specifically and directly respond to regional uplifting and exhumation, we compiled previous fluid inclusion data of 32 porphyry deposits in China by recalculating the fluid trapping depths and trapping depth reduction magnitude from early to late mineralization stage veins. The data reveal that the average trapping pressure ratio (Ave TPE/TPL) between early- and late-stage veins of the these deposits are 1.2–18.4, mainly in the range of 1.35–5.83, with average trapping pressure reduction (1?Ave TPL/TPE) from early- to late- stage veins are 17%–95%, and mainly in the range of 25%–83%. The fluid trapping pressure based mineralization depths most of the porphyry deposits in China had decreased from early to late vein stages by at least 450 m (900–5800 m predominant), or greater than 950 m when take the average depth reduction value, which is greater than the current gap between early- and late- stage veins of each deposit. We propose that the apparently greater mineralization depth reduction magnitude than the current elevation gaps between early and late veins are likely a consequence of syn-mineralization uplifting and exhumation process that often occurs in porphyry systems.

    • Origin of Quartz Cement in the Paleogene Sandstone Reservoir of Shahejie Formation, Bohai Bay Basin, China

      2022, 96(1):248-260. DOI: 10.1111/1755-6724.14859

      Abstract (135) HTML (0) PDF 80.45 M (262) Comment (0) Favorites

      Abstract:The precipitation of authigenic quartz plays a significant role to reduce the reservoir characteristics and enhance the stiffness of the rock. The Es1 sandstone of Shahejie Formation is acting as a significant hydrocarbon producing rock in the Nanpu Sag. Various methods like thin section petrography, cathodoluminescence (CL), scanning electron microscope (SEM, with EDS), and electron microprobe analysis has been used to reveal the origin of quartz cement as well as to evaluate the effect of quartz cement on reservoir quality. The studied sandstone is classified as immature to mature feldspathic litharenite and lithic arkose and consists of quartz, feldspar, rock fragments and micas. Petrographic studies and SEM analysis shows that the authigenic quartz is acting a significant cement that reduces the reservoir quality. Whereas clay minerals (kaolinite and mixed layer illite to smectite) are dominant in the Es1 sandstone, that can reduce the reservoir quality. SEM, CL and thin section analysis reveal that there are two stages of quartz cement in the studied samples; that are pore filling authigenic cement and quartz overgrowth cement. Fluid inclusion homogenization temperatures shows that stages of quartz cement were developed with continuous process from 70℃ to 130℃. Quartz cements were generally originated from I/S reaction, feldspar dissolution, conversion of rock fragments and pressure solution. Feldspar dissolution (K-feldspar) and kaolinite to illite reaction is an insignificant silica source for the silica cement which is internally precipitated in a close system with diffusion transporting mechanism. Overall, quartz cement significantly enhance the rock strengthen and brittleness effectively as well as it reduce the overall reservoir quality.

    • Geochemical Characterizations of Source and Depositional Environment of Hydrocarbons in the Lake Albert Rift Basin

      2022, 96(1):261-272. DOI: 10.1111/1755-6724.14862

      Abstract (141) HTML (0) PDF 4.34 M (255) Comment (0) Favorites

      Abstract:Despite the upsurge in hydrocarbon exploration in the Lake Albert Rift Basin (LARB) over the past three decades, systematic characterization of hydrocarbon compositions remains lacking, leading to uncertainties in source rock and oil generation determination. We characterized crude oil compositions and oil sand samples in the northern and southern subbasins of LARB. The relative abundance of normal and branched linear alkanes, hopanes, steranes, and aromatic hydrocarbon suggest that northern and southern hydrocarbons were deposited in anoxic to suboxic lacustrine environments and share similar biological source compositions (i.e., a mixture of plants and aquatic algae and bacteria). Relative to southern samples, northern samples show more negative δ13C values for oils, saturates and aromatics, indicating longer migration paths, and exhibit higher MPI-1, DNR-1 and 4-/1-MDBT ratios, indicating higher maturity. Between the two possible sets of source rocks (upper Miocene and Jurassic strata), the positive δ13C values of saturated hydrocarbons (average = ?20.5‰) suggest that the upper Miocene lacustrine shale is the most likely candidate. Oleanane index (<5% in our samples) does not exclude either source rock possibility, and C28/C29 regular sterane (average = 0.63) may be biased by high terrestrial inputs in a lacustrine setting. Together, our data show that northern and southern oils originate from the same source rocks but different oil kitchens. Given the similar geochemical characteristics of southern and northern oils, previous exploration successes in the northern subbasin likely suggest similar potential in the southern sector, while other elements influencing exploration success must be also evaluated.

    • Distribution of Selected Critical Elements in the Carboniferous Coal-bearing Series of the Upper Silesian and Lublin Coal Basins (Poland)

      2022, 96(1):273-292. DOI: 10.1111/1755-6724.14811

      Abstract (123) HTML (0) PDF 18.95 M (281) Comment (0) Favorites

      Abstract:The distribution of selected critical elements in the sedimentary rocks of the Carboniferous coal-bearing series within the Polish Coal Basins is presented. Critical elements such as Be, Mg, Si, P, Sc, V, Co, Y, Nb, In, Sb, La, Ce, Hf, Ta, W, Bi were analysed using inductively-coupled plasma mass spectrometry (ICP/MS). Concentrations of elements such as Sb, Bi, In and, to a slightly lesser extent, Nb, as well as Sc, show average concentrations higher than those from the upper continental crust. The average concentrations of elements like Hf, Mg, P, Y, La, and Ce are slightly lower than in the upper continental crust. Other elements, such as Be, Co, Si, Ta, W and V have average concentrations that are similar, but slightly enriched or slightly depleted, relative to the upper continental crust. The research showed enrichment of some critical elements in the analysed samples, but not high enough that extraction would be economically viable. Statistical methods, which include correlation coefficients between elements and cluster analysis, reveal a strong positive correlation between elements like Be, Bi, Nb, Sc, Ta, W and V. Very high, almost total, positive correlation is also noted between La and Ce.

    • The Biomarkers in the Mesoproterozoic Organic-rich Rocks of North China Craton: Implication for the Precursor and Preservation of Organism in the Prokaryotic Realm

      2022, 96(1):293-308. DOI: 10.1111/1755-6724.14773

      Abstract (137) HTML (0) PDF 5.60 M (225) Comment (0) Favorites

      Abstract:Mesoproterozoic marine organic-rich rocks are widely distributed in the North China Craton, include the Gaoyuzhuang (GYZ), the Hongshuizhuang (HSZ), and the Xiamaling (XML) formations. According to the Tmax value and isomerisation ratio of C31 homohopanes, the XML, HSZ, and GYZ samples were in low mature, mature and high mature stage, respectively. Biomarker distribution in extractable organic matter (EOM) of three Mesoproterozoic organic-rock samples in different maturity were analysed to reveal the organic precursor and preservation pathway of in the Mesoproterozoic Combined with gold-tube pyrolysates of three Mesoproterozoic samples, it could further illuminate the chemical composition of Mesoproterozoic kerogen, given excluding. The results indicated that the three formations were all deposited under reducing condition and their organic precursors mainly were some aquatic organisms. High content of rearranged hopanes was detected in EOM of XML and HSZ samples, whereas they were relatively low in the high mature GYZ sample. Contrast to that in EOM, the relative concentration of rearranged hopanes sharply decreased in the gold-tube pyrolysates of the XML kerogen, then slightly increased but was still significantly lower than the EOM of XML sample, which indicated that catalysis of clay minerals in the early diagenesis only changed the chemical composition of the unstable functional groups of the kerogen during the preservation. Due to the thriving heterotrophic microbes and low sink rate of particulate organic matter during the Mesoproterozoic, primary producers suffered extensive degradation during sinking process, only some resistant biopolymers lacking of lipid compounds survived from heterotrophic degradation, while heterotrophic microbes contained more proportion of organic precursors. Abundant pristane (Pr) and phytane (Ph) were only released in high mature stage because of the protection of the macromolecular structure of resistant biopolymers which prevented biomarkers from being altered by the thermal stress. The absence of 13α(n-alkyl)-tricyclic terpanes in the high matured hydrocarbon products also indicated the different precursors between different parts of Mesoproterozoic kerogen. The evolution of the biomarker composition and content of Mesoproterozoic kerogen showed some special characteristics differing from those of Phanerozoic kerogen. The total concentrations of hopanes displayed with an order of low mature stage > high mature stage > mature stage. Relative content of rearranged hopanes in the hydrocarbon generated in high mature stage was significantly lower than that in the low maturity stage. The ratios of Pr/n-C17 and Ph/n-C18 increased with thermal maturity, and the ratio of nC21-/nC22+ decreased in the high maturity stage, thus displaying another order of mature stage > high maturity stage > low maturity stage. The unique preservation pathway of Mesoproterozoic organisms was attributed to the special evolution characteristics of biomarker distributions, which should be considered in the Mesoproterozoic marine environment and biological studies.

    • Characteristics of Hydrogen-rich Coals in Southern China: Implications from Organic Geochemistry and Carbon Isotopic Compositions

      2022, 96(1):309-320. DOI: 10.1111/1755-6724.14714

      Abstract (146) HTML (0) PDF 6.99 M (210) Comment (0) Favorites

      Abstract:The organic geochemical characteristics of hydrogen-rich coal in southern China were investigated synthetically through organic geochemistry and carbon isotope analyses. The results showed that the hydrogen contents of the test samples were more than 5.0% and the H/C atomic ratios were between 0.76–1.06. Samples were found to be composed mostly of Type II-III kerogen, consistent with good hydrocarbon-generation potential. The Ro (0.54–1.10%) and Tmax (430–453°C) values imply that the hydrogen-rich coals were in low maturity to mature stages. Stable carbon isotopic ratios (δ13Corg) of the samples used varied from ?24.5‰ to ?23.4‰, the barkinite content ranging from 13.9% to 83.3%, indicating a predominantly terrestrial origin with marine influence during coal formation. Some organic geochemical parameters showed corresponding changes as the hydrogen content increased from 5.0% to 7.0%, however, the source inputs changed significantly when hydrogen content was greater than 6.0%. Terrestrial higher plants gradually become predominant within the coal-forming materials, whereas this dominant position is not apparent at lower hydrogen contents, which is attributable to the strong seawater effect during the hydrogen-rich coal formation process.

    • Middle Permian Mixed Siliciclastic-Carbonate System on the Northwestern Margin of the Indian Plate, Pakistan: Implications for Paleoclimate and Carbonate Platform Evolution

      2022, 96(1):321-336. DOI: 10.1111/1755-6724.14737

      Abstract (124) HTML (0) PDF 202.76 M (212) Comment (0) Favorites

      Abstract:A mixed siliciclastic-carbonate system that responds to changes in Permian climate and subsequent carbonate platform evolution is investigated using microscopic details of the Middle Permian Amb Formation (Fm.), in Saiyiduwali section, Khisor Range, northern Pakistan. Thin sections were made from rocks throughout the stratigraphic section of the Amb Fm. and analyzed with an emphasis on carbonate and clastic microfacies, and the latter interpreted within the existing chronostratigraphic framework. Outcrop observations reveal that the units comprise coarse-grained, channelized, ripple-marked, and burrowed sandstone and sandy, fossiliferous limestone with minor marls and shale intercalations, suggesting deposition in a subaqueous tide-dominated delta to beach barrier. Based on the determined seven microfacies coupled with outcrop observation, the Amb Fm. was deposited in a tide-influenced subaqueous delta to middle shelf environment under fluctuating sea level. The deposition of compositionally mature sandstone in the lower part of the formation suggests reworking of detritus from the rift shoulders and an adjacent source area with an ambient warm and humid climate. The stratal mixing of carbonates and compositionally mature siliciclastic units in the middle part suggest deposition under tectonic and climate-induced terrigenous and carbonate fluxes to the basin. Thus the deposition shows a perfect transition from clastic-dominated deltaic to pure carbonate platform settings as a result of warm climate and tectonics. This Middle Permian warming is confirmed by sea-level rise and the presence of a temperature-sensitive fusulinid fauna in association with photozoan-based ooids. Deposition of the Amb Fm. and establishment of a carbonate platform are envisaged to be associated with major rifting of northern Gondwana, which subsequently resulted in the development of a rift basin at the passive margin of the NW Indian Plate then in northern Pakistan.

    • Reassessment of the Distribution of Mantle CO2 in the Bohai Sea, China: The Perspective from the Source and Pathway System

      2022, 96(1):337-347. DOI: 10.1111/1755-6724.14770

      Abstract (189) HTML (0) PDF 52.36 M (477) Comment (0) Favorites

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

    • Application of 3D Static Modelling in Reservoir Characterization: A Case Study from the Qishn Formation in Sharyoof Oil Field, Masila Basin, Yemen

      2022, 96(1):348-368. DOI: 10.1111/1755-6724.14766

      Abstract (144) HTML (0) PDF 23.85 M (365) Comment (0) Favorites

      Abstract:Three-dimensional (3D) static modelling techniques are applied to the characterization of the Qishn Formation (Fm.) in the Sharyoof oil field locating within the Masila basin, southeastern Yemen. The present study was initiated by the seismic structural interpretation, followed by building a 3D structural framework, in addition to analysing well log data and from these, 3D facies and petrophysical models are constructed. In the Sharyoof oil field, the Qishn Fm. exhibits depth values within the range of 400–780 m below sea level, with a general increase towards the SSE. A set of high dip angle normal faults with a general ENE–WSW trend dissect the rocks. The strata are also folded as a main anticline with an axis that is parallel to the fault trend, formed as a result of basement uplift. According to the facies models, the Qishn Fm. comprises 43.83% limestone, 21.53% shale, 21.26% sandstone, 13.21% siltstone and 0.17% dolomite. The Qishn Carbonates Member has low porosity values making it a potential seal for the underlying reservoirs whereas the Upper Qishn Clastics S1A and C have good reservoir quality and S1B has fair reservoir quality. The Upper Qishn Clastics S2 and S3 also have fair reservoir quality, while the Lower Qishn Clastics zone has good reservoir quality. The water saturation decreases towards the west and east and increases towards north and south. The total original oil in-place (OOIP) of the Upper Qishn clastics is 106 million STB within the S1A, S1C and S2 zones. Drilling of development wells is recommended in the eastern study area, where good trapping configuration is exhibited in addition to the presence of a potential seal (Upper Qishn Carbonates Member) and reservoir (Qishn Clastics Member) with high porosity and low water saturation.

    • Evidence of Glacial Erratic Rollover Revealed by 10Be and 26Al Concentration Variations

      2022, 96(1):369-375. DOI: 10.1111/1755-6724.14685

      Abstract (160) HTML (0) PDF 41.65 M (301) Comment (0) Favorites

      Abstract:Cosmogenic nuclide exposure dating is one of the most intensively applied dating methods with which to study glacial geomorphology. Glacial erratics have been the major dating objective in many studies. Some research has proposed that glacial erratics may undergo rollover and re-transportation during the late exposure stage, which can affect the dating results. However, there is no direct evidence to confirm this possibility. In this study, we collected seven samples from a vertical section inside a glacial erratic in the paleo-Daocheng ice cap in the southeastern Tibetan Plateau, measuring their contents of the cosmogenic nuclides 10Be and 26Al. The results show that from the top to the bottom, the concentrations of 10Be were (1.21 ± 0.05) × 106, (1.00 ± 0.02) × 106, (0.88 ± 0.03) × 106, (0.77 ± 0.02) × 106, (0.75 ± 0.03) × 106, (0.95 ± 0.03) × 106 and (1.46 ± 0.04) × 106 atoms/g. The 10Be concentrations decreased from (1.21 ± 0.05) × 106 atoms/g to (0.75 ± 0.03) × 106 atoms/g and then increased to (1.46 ± 0.04) × 106 atoms/g, which is not consistent with the theoretical prediction of a gradual decrease. This phenomenon indicates that the glacial erratic may have rolled over at least once. The lower surface of the erratic could have been on top at some time in the past. Therefore, its exposure age was greater than the exposure age that was expected, based on its current orientation. This study provides numerical evidence for an erratic rollover event.

    • Spectral-based Probabilistic Seismic Hazard Analysis for Fethiye, Muğla

      2022, 96(1):376-385. DOI: 10.1111/1755-6724.14797

      Abstract (141) HTML (0) PDF 85.63 M (494) Comment (0) Favorites

      Abstract:Fethiye is an important region located in the eastern part of the Mediterranean Basin. This region which is the most active part of the south-western Anatolia extensional tectonic regime, has been effected by earthquakes, submarine landslides and tsunamis throughout the history due to the existence of the complex active plate boundary zone. The active area has been exposed to ground motion that had the potential to damage vulnerable structures. Therefore, a detailed assessment of seismic hazard is necessary for the prevention of potential damage. In this context, probabilistic seismic hazard analysis is performed by R-CRISIS-18.3 using the refined parameters computed from Seismic Hazard Harmonization for Europe (SHARE) project. Spatial distribution of spectral acceleration at T = 0.2 s and T = 1.0 s for the earthquake levels that corresponds to the average return period of 72, 475 and 2475 years is calculated. Hazard curves for the central region of Fethiye district are generated. The results are discussed and compared with the values obtained from the Revision of Turkish Seismic Hazard Map Project (UDAP-?-13-06). These local results of probabilistic seismic hazard analysis will provide the basis for the preparation of seismic risk maps as future work.

    • Indosinian Supergene Karsts in the Qaidam Basin, NW China: Evidence from Paleo-tectonics, Paleoclimates and Paleo-fluids

      2022, 96(1):386-399. DOI: 10.1111/1755-6724.14861

      Abstract (148) HTML (0) PDF 16.84 M (384) Comment (0) Favorites

      Abstract:In the Qaidam basin, Northwest China, karstic fissures and caves are developed in many places of the Lower Carboniferous Chengqianggou Fm. and Huaitoutala Fm. and the Upper Carboniferous Keluke Fm., in which are found typical karstic marks. Several suites of transgressive carbonate rocks formed during the Late Paleozoic epoch are preserved as reservoir properties in the Qaidam basin, with paleokarst-related cave-fractured diagenetic structures, which provided the basis for cave-fractured development. Carbonate and clastic samples covering or infilling caves and fractures in Carboniferous strata were collected in the eastern Qaidam basin to focus on petrological and geochemical analyses of karst and infilling materials. Based on this study of the Caledonian diagenetic sequence, and bitumen-infilled inclusion temperature and burial history, there existed a continuous atmospheric freshwater leaching process, which played a critical role in the construction of the Carboniferous supergene paleokarsts. Investigation and survey of the tectonic setting, plate paleolatitude and river development intensity also proves that there was abundant rainfall during the Indosinian period, after which the strata undergo a shallow burial process. Because Indosinian period is earlier than the key timing of hydrocarbon-generation of the Carboniferous source rocks, this kind of karst reservoir has potential significance for oil-gas resources in this area.

    • Acta Geologica Sinica (English Edition) Calls for Submission of Review Papers

      2022, 96(1):400-400.

      Abstract (170) HTML (0) PDF 315.91 K (240) Comment (0) Favorites

      Abstract:

Chief Editor:HOU Zengqian

Governing Body:China Association for Science and Technology

Organizer:Geological Society of China

start publication :1922

ISSN:ISSN 1000-9515

CN:CN 11-2001/P

  • Most Read
  • Most Cited
  • Most Downloaded
Press search
Search term
From To