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The Qinling Orogen and intracontinental orogen mechanism
... Based on the 1:12,000,000 Geological Map of China (Ma et al. 1996). The geological history of this orogen began in the Paleoproterozoic and continued into the Mesozoic and Cenozoic (Indosinian and Yanshanian orogenies; see text for more details and Zhang et al 1995). Square indicates approximate position of study area shown in Fig. 2 are first-order subsidiary faults characterized by early compressional shearing and late extensional shearing (Fig. 2). ...
... Near the historical city of Xi'an, a geosuture is marked by the Shang-Dan (Shangnan-Danfeng) fault and defines the southern boundary of the Qinling Orogen (inset of Fig. 2). Details of the geodynamic evolution of the Qinling Orogen can be found in Zhang et al. (1995), Meng and Zhang (2000) and Ratschbacher et al. (2003). An understanding of this evolution is an essential prerequisite in order to gain insights into regional and local metallogenesis. ...
... Because Middle-Lower Triassic turbidites are common in the southern and western parts of the Qinling Orogen, and are also locally found in the eastern Qinling Orogen (Jin 1988;Yin and Nie 1996), the final stages of the continental collision between the South and North China plates would have occurred later than 230 Ma. As localized collisions might have occurred from about 250 Ma, this age may be the best estimate for the beginning of this continental collision and is in accor-dance with radiometric ages (Zhang et al. 1995;Zheng et al. 2003). During these final stages of collision, a stack of underthrust slabs formed within the Qinling Orogen (Fig. 7G). ...
In this book, we introduced the geochemical and geological characteristics, the genesis and ore-forming geodynamic backgrounds of four orogenic-type base metal deposits in the northern margin of the North China Craton.
... The north and south Ordos Basins have different tectonic histories and very distinctive sedimentation styles (Liu, 1998;Yang, 2001;Yang et al., 2005;Liao et al., 2007;Ritts et al., 2009). The evolution of the southern Ordos Basin during the early Mesozoic was controlled by two deformation beltsthe Qinling orogenic belt to the south, and the Liupanshan thrust and fold belt to the west (Mattauer et al., 1985;Peltzer et al., 1985;Zhang et al., 1995Zhang et al., , 1999Xue et al., 1996;Ratschbacher et al., 2000). ...
... The Qinling orogenic belt to the south includes the north, south, and west Qinling orogenic belts (Figs 1, 9). It experienced complex late Paleozoic to early Mesozoic arc-continent and continent-continent suturing and collision (Kröner et al., 1993;Zhou et al., 1994;Zhang et al., 1995;Bruguier et al., 1997). As a result, different source rocks, including Archean to Paleoproterozoic metamorphic rocks, and late Paleozoic and Mesozoic sedimentary and igneous rocks, have been structurally juxtaposed together (Zhou et al., 1994;Zhang et al., 1995) (Fig. 1). ...
... It experienced complex late Paleozoic to early Mesozoic arc-continent and continent-continent suturing and collision (Kröner et al., 1993;Zhou et al., 1994;Zhang et al., 1995;Bruguier et al., 1997). As a result, different source rocks, including Archean to Paleoproterozoic metamorphic rocks, and late Paleozoic and Mesozoic sedimentary and igneous rocks, have been structurally juxtaposed together (Zhou et al., 1994;Zhang et al., 1995) (Fig. 1). ...
... Based on the 1:12,000,000 Geological Map of China (Ma et al. 1996). The geological history of this orogen began in the Paleoproterozoic and continued into the Mesozoic and Cenozoic (Indosinian and Yanshanian orogenies; see text for more details and Zhang et al 1995). Square indicates approximate position of study area shown in Fig. 2 are first-order subsidiary faults characterized by early compressional shearing and late extensional shearing (Fig. 2). ...
... Near the historical city of Xi'an, a geosuture is marked by the Shang-Dan (Shangnan-Danfeng) fault and defines the southern boundary of the Qinling Orogen (inset of Fig. 2). Details of the geodynamic evolution of the Qinling Orogen can be found in Zhang et al. (1995), Meng and Zhang (2000) and Ratschbacher et al. (2003). An understanding of this evolution is an essential prerequisite in order to gain insights into regional and local metallogenesis. ...
... Because Middle-Lower Triassic turbidites are common in the southern and western parts of the Qinling Orogen, and are also locally found in the eastern Qinling Orogen (Jin 1988;Yin and Nie 1996), the final stages of the continental collision between the South and North China plates would have occurred later than 230 Ma. As localized collisions might have occurred from about 250 Ma, this age may be the best estimate for the beginning of this continental collision and is in accor-dance with radiometric ages (Zhang et al. 1995;Zheng et al. 2003). During these final stages of collision, a stack of underthrust slabs formed within the Qinling Orogen (Fig. 7G). ...
Isotope geochemistry of the Tieluping silver-lead deposit, Henan, China: A case study of orogenic silver-dominated deposits and related tectonic setting Abstract The Tieluping silver deposit, which is sited along NE-trending faults within the high-grade meta-morphic basement of the Xiong'er Terrane in the Qin-ling orogenic belt, is part of an important, recently discovered Mesozoic orogenic-type Ag-Pb belt. Ore formation includes three stages: an early barren quartz-pyrite stage (E), an intermediate polymetallic sulfide ore stage (M), and a late barren carbonate stage (L). Car-bon, sulfur and lead isotope systematics indicate that the E-stage fluids are deeply sourced; the L-stage fluids are shallow-sourced meteoric water; whereas the M-stage fluids are a mix of deep-sourced and shallow-sourced fluids. Sulfur and lead isotope data show that the ore-forming fluids must have originated from a source with elevated radiogenic lead and low d 34 S values, that differs significantly from exposed geologic units in the Xiong'er Terrane, the lower crust and the mantle. This supports the view that the carbonate-shale-chert sequences of the Guandaokou and Luanchuan Groups south of the Machaoying fault might be the favorable sources, al-though little is known about their isotopic compositions. A tectonic model that combines collisional orogeny, metallogeny and hydrothermal fluid flow is proposed to explain the formation of the Tieluping silver deposit. During the Mesozoic collision between the North China Craton and South China Block (Early-Mid Triassic Indosinian Orogeny), crustal slabs containing the carbonate-shale-chert sequences of the Guandaokou and Luanchuan Groups, locally rich in organic matter (carbonaceous shale), were thrust northwards beneath the Xiong'er Terrane along the Machaoying fault. Metamorphic devolatilisation of this underthrust slab probably provided the ore-forming fluids to develop the Ag-Pb ore belt, which includes the Tieluping silver deposit. Fluids and magmas were emplaced during extensional stages related to the Jurassic-Cretaceous Yanshanian Orogeny. Keywords Orogenic silver deposit AE Isotope geochemistry AE Xiong'er Terrane AE Qinling Orogen AE China Introduction
... Based on the 1:12,000,000 Geological Map of China (Ma et al. 1996). The geological history of this orogen began in the Paleoproterozoic and continued into the Mesozoic and Cenozoic (Indosinian and Yanshanian orogenies; see text for more details and Zhang et al 1995). Square indicates approximate position of study area shown in Fig. 2 are first-order subsidiary faults characterized by early compressional shearing and late extensional shearing (Fig. 2). ...
... Near the historical city of Xi'an, a geosuture is marked by the Shang-Dan (Shangnan-Danfeng) fault and defines the southern boundary of the Qinling Orogen (inset of Fig. 2). Details of the geodynamic evolution of the Qinling Orogen can be found in Zhang et al. (1995), Meng and Zhang (2000) and Ratschbacher et al. (2003). An understanding of this evolution is an essential prerequisite in order to gain insights into regional and local metallogenesis. ...
... Because Middle-Lower Triassic turbidites are common in the southern and western parts of the Qinling Orogen, and are also locally found in the eastern Qinling Orogen (Jin 1988;Yin and Nie 1996), the final stages of the continental collision between the South and North China plates would have occurred later than 230 Ma. As localized collisions might have occurred from about 250 Ma, this age may be the best estimate for the beginning of this continental collision and is in accor-dance with radiometric ages (Zhang et al. 1995;Zheng et al. 2003). During these final stages of collision, a stack of underthrust slabs formed within the Qinling Orogen (Fig. 7G). ...
... Based on the 1:12,000,000 Geological Map of China (Ma et al. 1996). The geological history of this orogen began in the Paleoproterozoic and continued into the Mesozoic and Cenozoic (Indosinian and Yanshanian orogenies; see text for more details and Zhang et al 1995). Square indicates approximate position of study area shown in Fig. 2 are first-order subsidiary faults characterized by early compressional shearing and late extensional shearing (Fig. 2). ...
... Near the historical city of Xi'an, a geosuture is marked by the Shang-Dan (Shangnan-Danfeng) fault and defines the southern boundary of the Qinling Orogen (inset of Fig. 2). Details of the geodynamic evolution of the Qinling Orogen can be found in Zhang et al. (1995), Meng and Zhang (2000) and Ratschbacher et al. (2003). An understanding of this evolution is an essential prerequisite in order to gain insights into regional and local metallogenesis. ...
... Because Middle-Lower Triassic turbidites are common in the southern and western parts of the Qinling Orogen, and are also locally found in the eastern Qinling Orogen (Jin 1988;Yin and Nie 1996), the final stages of the continental collision between the South and North China plates would have occurred later than 230 Ma. As localized collisions might have occurred from about 250 Ma, this age may be the best estimate for the beginning of this continental collision and is in accor-dance with radiometric ages (Zhang et al. 1995;Zheng et al. 2003). During these final stages of collision, a stack of underthrust slabs formed within the Qinling Orogen (Fig. 7G). ...
The Tieluping silver deposit, which is sited along NE-trending faults within the high-grade metamorphic basement of the Xionger Terrane in the Qinling orogenic belt, is part of an important, recently discovered Mesozoic orogenic-type Ag-Pb belt. Ore formation includes three stages: an early barren quartz-pyrite stage (E), an intermediate polymetallic sulfide ore stage (M), and a late barren carbonate stage (L). Carbon, sulfur and lead isotope systematics indicate that the E-stage fluids are deeply sourced; the L-stage fluids are shallow-sourced meteoric water; whereas the M-stage fluids are a mix of deep-sourced and shallow-sourced fluids. Sulfur and lead isotope data show that the ore-forming fluids must have originated from a source with elevated radiogenic lead and low 34S values, that differs significantly from exposed geologic units in the Xionger Terrane, the lower crust and the mantle. This supports the view that the carbonate-shale-chert sequences of the Guandaokou and Luanchuan Groups south of the Machaoying fault might be the favorable sources, although little is known about their isotopic compositions. A tectonic model that combines collisional orogeny, metallogeny and hydrothermal fluid flow is proposed to explain the formation of the Tieluping silver deposit. During the Mesozoic collision between the North China Craton and South China Block (Early-Mid Triassic Indosinian Orogeny), crustal slabs containing the carbonate-shale-chert sequences of the Guandaokou and Luanchuan Groups, locally rich in organic matter (carbonaceous shale), were thrust northwards beneath the Xionger Terrane along the Machaoying fault. Metamorphic devolatilisation of this underthrust slab probably provided the ore-forming fluids to develop the Ag-Pb ore belt, which includes the Tieluping silver deposit. Fluids and magmas were emplaced during extensional stages related to the Jurassic-Cretaceous Yanshanian Orogeny.
... Beginning in the Early to Late Triassic, the Qinling Orogenic Belt formed the southern boundary of Ordos Basin (Xie and Heller, 2013). It experienced complex arc-continent and continentcontinent suturing and collision during the Late Palaeozoic to Early Mesozoic (Kröner et al., 1993;Zhang et al., 1995;Bruguier et al., 1997). As a result, different source rocks, Archean to Paleoproterozoic metamorphic rocks, Late Palaeozoic and Mesozoic sedimentary and igneous rocks, have been structurally juxtaposed together (Zhang et al., 1995). ...
... It experienced complex arc-continent and continentcontinent suturing and collision during the Late Palaeozoic to Early Mesozoic (Kröner et al., 1993;Zhang et al., 1995;Bruguier et al., 1997). As a result, different source rocks, Archean to Paleoproterozoic metamorphic rocks, Late Palaeozoic and Mesozoic sedimentary and igneous rocks, have been structurally juxtaposed together (Zhang et al., 1995). ...
Petrographic and geochemical characteristics of the Upper Triassic sandstones in the western Ordos Basin were studied to provide insight into weathering characteristics, provenance, and tectonic implications. Petrographic features show that the sandstones are characterized by low‐medium compositional maturity and textural maturity. The CIA and CIW values reveal weak and moderate weathering history in the source area. The geochemical characteristics together with palaeocurrent data show that the northwestern sediments were mainly derived from the Alxa Block with a typical recycled nature, while the provenance of the western and southwestern sediments were mainly from the Qinling‐Qilian Orogenic Belt. The tectonic setting discrimination diagrams signify that the parent rocks of sandstones in the western and southern Ordos Basin were mainly developed from continental island arc, which is closely related to the evolution of the Qinling‐Qilian Orogenic Belt. However, the sandstones in the northwestern Ordos Basin show complex features, which may be resulted from a typical recycling process. Overall evidence from petrography, geochemistry and sedimentology, together with previous researches suggest the Kongtongshan and Helanshan areas were the southwestern and northwestern boundary of the Ordos Basin, respectively, and there was no clear boundary between the Hexi Corridor Belt and Ordos Basin, where a large, uniform sediment dispersal system developed during the Late Triassic.
... The Qinling region had long been involved in the interactions among the Gondwana, Laurasia, and Paleo-Tethyan tectonic systems starting in the Late Ordovician (Kröner et al. 1993;Zhang et al. 1995Zhang et al. , 2001Xue et al. 1996;Meng & Zhang 2000;Ratschbacher et al. 2003). From c. 450 Ma, those tectonic interactions involved collision that sutured the Yangtze Craton with the North China Craton, and closed the intervening Shang-Dan Ocean. ...
... From c. 400 Ma to c. 250 Ma, the Mian-Lue Ocean continued to open and the Shang-Dan Ocean reopened. During the Mesozoic era, the Qinling region has been involved in the interactions among the Pacific Plate, Indian Plate, and Siberian block starting in the Early Triassic (Ames et al. 1993;Li et al. 1993;Hacker et al. 1998;Zhang et al. 1995Zhang et al. , 2001Chen et al. 2004a). From c. 240 Ma to c. 140 Ma, those tectonic interactions include closing of the Mian-Lue and Shang-Dan oceans and the full-scale collision and subduction of the Yangtze continental plate beneath the southern margin of the North China Orogen. ...
The Qiyugou deposit, in the Xiong’er terrane, Qinling Orogen, is an auriferous breccia pipe developed in continental collision setting. The breccia pipe exhibits variable-sized clasts and clast mixing, which are typical of fluidized breccias. Brecciation, alteration, and gold mineralization are related to granite porphyry emplaced at c. 134 Ma. However, the relationships of the CO2-rich ore-forming fluids with the tectonic setting, structural control, granite magma evolution, and hydrothermal brecciation have not been clearly discussed. New fluid inclusion data presented in this paper indicate that the formation of the Qiyugou deposit includes: (1) an early stage defined by K-feldspar-epidote-quartz-pyrite assemblage; (2) a middle stage of quartz-polymetallic sulphides; and (3) a late stage typified by quartzcarbonate±adularia. Alteration and mineralization resulted from escape of hot (>320 °C), high-salinity (>40 wt% NaCl eq.) magmatic fluid exsolved during the final stage of crystallization of the granite porphyry. Significant pressure drop from 85–90 to 20–38 MPa resulted in breccia formation and precipitation of quartz, sulphides, and gold. A vapour phase was produced at 355–403 °C due to fluid boiling, and then was cooled and condensed under near-critical conditions to a moderately saline, warm liquid. Aqueous-carbonic inclusions were formed by trapping of heterogeneous fluids unmixed from the original H2O-CO2-NaCl fluid. Late magmatic-hydrothermal fluid mixed with meteoric fluid, and was cooled and diluted to produce lukewarm, low salinity fluid that precipitated clear quartz and calcite with little or no mineralization. Our review of the literature suggests that the brecciation and mineralization likely coincided with sinistral transtensive faulting during 140–120 Ma. Therefore, synthesis of the foregoing geochemical information with pertinent geological information from the literature lead us to propose that fluidization and seismic pumping were important in the breccia formation and associated gold mineralization at Qiyugou.
... Wang et al., 2013), and by the NE-SW-trending fault zone extending from Honghe to Hanzhong (Fig. 1a). Previous studies documented that the Yangtze Block consists of highly metamorphosed Neoarchean-Paleoproterozoic crystalline basement (i.e., continental core) similar to the granite-greenstone belt; e.g., the original Kangding Group (SBGMR, 1991), greenschist facies metamorphosed Meso-Neoproterozoic folded (or transitional) basement, and unmetamorphosed Sinian-Mesozoic clastic and carbonate rock cover (SBGMR, 1991;Zhang et al., 1995Zhang et al., , 2001Dong et al., 2011Dong et al., , 2012Peng et al., 2012). The folded basement is composed mainly of metamorphic volcanic and pyroclastic rocks (e.g., the Yanbian Group) and typical metasedimentary rocks (e.g., the Huili Group), which are considered to constitute the metamorphic basement of the western part of the Yangtze Block (SBGMR, 1991). ...
... The studied gabbros have lower SiO 2 contents (49.59-50.94 wt.%), higher Mg# values (35-45), and higher Cr (46.6-91.7 ppm), Co (36.3-46.5 ppm), and Ni (10.4-28.6 ppm) contents than do liquids produced by partial melting of any regionally available crustal rocks, i.e., granitoid liquids (e.g., Zhang et al., 1995;Kato et al., 1997;Gao et al., 1998;Rapp et al., 2003). Similarly, the studied gabbro-diorites show a higher variation in SiO 2 contents (47.67-57.62 ...
Voluminous Neoproterozoic gabbros, gabbro-diorites, and granites are exposed in the Baoxing area along the western margin of the Yangtze Block. We present here zircon U–Pb and Lu–Hf isotope data, as well as whole-rock geochemical data for these rocks, which help constrain the tectonic characteristics and evolution of the western margin of the Yangtze Block. Zircons from these rocks have high Th and U contents and Th/U ratios (> 0.2), and show striped absorption patterns, growth striations, or zoning, indicating a typical magmatic origin. Zircon U–Pb dating and Lu–Hf isotope results show that the gabbros formed at ca. 850 Ma with εHf = + 5.44 to + 11.94, and a single-stage model age (THf) of 1.04 Ga, suggesting a depleted-mantle-derived source. The gabbro-diorites formed at ca. 800 Ma with major εHf = + 3.99 to + 14.62 and THf = 0.97 Ga, and minor εHf = + 0.68 to + 5.66 and THf = 1.27 Ga, again suggesting a depleted-mantle-derived source. The granites were emplaced at ca. 770 Ma with εHf = + 2.53 to + 10.58 and THf = 1.07 Ga, indicating that they were derived from the partial melting of juvenile crust. The geochemical data show that the gabbros and gabbro-diorites are characterized by low SiO2 contents, high Mg# values and Cr, Co, and Ni contents, significant enrichment in light rare-earth elements and large-ion lithophile elements, depletion in high field strength elements (e.g., Nb, Ta, Zr, and Hf), and relatively high Nb/U, Ta/U, and Ce/Pb ratios. These data suggest that the rocks were derived from the partial melting of depleted lithospheric mantle that had been metasomatized by subduction-derived fluids or melts, and which underwent very minimal crustal contamination during magma evolution and ascent. The granites have high SiO2 and K2O, and low MgO contents, exhibit enrichment in Rb, Ba, Th, and Pb and depletion in Nb, Ta, and Ti, and have low Sr/Y and (La/Yb)N ratios and high Y and Yb contents, which together with their Hf isotopic compositions imply a juvenile crust source. Taking into account regional pre-750 Ma arc-related magmatism and the subsequent extensional setting, it is proposed that a long-lived, active continental-margin setting may have evolved along the western margin of the Yangtze Block during the Neoproterozoic, and that the coeval granitic and mafic rocks in the Baoxing area were formed by the subduction of the western Yangtze Block.
... Widespread and episodic thermal events recorded in Phanerozoic zircons of lower crust xenoliths, as synthesized in this study, generally corresponds to the Caledonian, Hercynian, Indosinian, Yanshanian, and Himalayan orogenies on the circum-craton mobile belts (Figs. 6 and 7). To the south of the NCC, the Dabie-Qinling-Qilian orogenic belts are composed of three distinct tectonostratigraphic units and underwent three main tectonic evolutionary stages (Zhang et al., 1995(Zhang et al., , 1996. The formation of the orogenic basements in Precambrian was followed by the plate tectonic evolution in Neoproterozoic-Middle Triassic with the northward subduction of the Paleotethysian Ocean and the collision of the north Qinling arc system into the NCC in the Caledonian ( Fig. 7; Liu et al., 2011). ...
... The formation of the orogenic basements in Precambrian was followed by the plate tectonic evolution in Neoproterozoic-Middle Triassic with the northward subduction of the Paleotethysian Ocean and the collision of the north Qinling arc system into the NCC in the Caledonian ( Fig. 7; Liu et al., 2011). The closure of the Paleotethysian Ocean led to continent-continent obliquely diachronous collision during late Hercynian and Indosinian (Li et al., 1993;Zhang et al., 1995Zhang et al., , 1996Meng and Zhang, 2000;Sun et al., 2002;Dong et al., 2011a, b). The final phase is marked by the Cretaceous-Cenozoic intracontinental evolutionary stage in the Yanshanian and Himalayan times. ...
A comprehensive synthesis of U–Pb geochronology and Hf isotopes of zircons from granulite/pyroxenite xenoliths entrained in Phanerozoic magmatic rocks and inherited xenocrysts from the associated lower crust rocks from various domains of the North China Craton (NCC) provides new insights into understanding the Phanerozoic evolution of the lower crust in this craton. Episodic widespread magma underplating into the ancient lower crust during Phanerozoic has been identified throughout the NCC from early Paleozoic to Cenozoic, broadly corresponding to the Caledonian, Hercynian, Indosinian, Yanshanian, and Himalayan orogenies on the circum-craton mobile belts. The early Paleozoic (410–490 Ma) ages come from xenoliths in the northern and southern margins as well as the central domain of the Eastern Block of the craton which mark the first phase of Phanerozoic magma underplating since the final cratonization of the NCC in the Paleoproterozoic. The magmatism coincided with the northward subduction of the Paleotethysian Ocean in the south and the southward subduction of the Paleoasian Ocean in the north. The subduction not only triggered magma underplating but also led to the emplacement of the diamondiferous kimberlites on the craton, marking the initiation of decratonization. The late Paleozoic event as represented by the 315 Ma garnet pyroxenite and/or lherzolite xenoliths in Hannuoba was restricted to the northern and southern margins of the craton, correlating with the arc magmatism continuous associated with the subduction of the Paleotethysian and Paleoasian Oceans and resulting in the interaction between the melts from subducted slabs and the lithospheric mantle/lower crust. The early Mesozoic event also dominantly occurred in the northern and southern margins and was related with the final closure of the Paleotethysian and Paleoasian Oceans as well as the collisional orogeny between the NCC and the Yangtze Craton. The late Mesozoic (ca. 120 Ma) was a major and widespread magmatic event which manifested throughout the NCC, associated with the geothermal overturn due to the giant south Pacific mantle plume. The Cenozoic magmatism, identified only in the dark clinopyroxenite xenoliths in the Hannuoba, was probably induced by the Himalayan movement in eastern Asia and might also have been influenced by the subduction of the Pacific Ocean to some extent. These widespread and episodic magma underplating or rejuvenation of the ancient lower crust beneath the NCC revealed by U–Pb and Hf isotope data resulted from the corresponding addition of juvenile materials from mantle to lower crust, with a mixing of the old crust with melts. The process inevitably resulted in the compositional modification of the ancient lower crust, similar to the compositional transformation from the refractory lithospheric mantle to a fertile one through the refractory peridotite — infiltrated melt reaction as revealed in the lithospheric mantle beneath the craton.
... 2.8-2.5 Ga (Kroner et al. 1988). The craton consists of a basement of Archean to Proterozoic metamorphic rocks that are overlain by Sinian metasedimentary and metavolcanic rocks immediately north of the western Qinling belt (Hsu et al. 1987;Zhang et al. 1995). These schists, quartzites, amphibolites, and marbles, in part, comprise what has been termed the Kuanping Group (Fig. 1). ...
... The leading passive margin strata of the Yangtze craton form the southern boundary of the Qinling-Dabie-Sulu orogen. The basement of the craton comprises Archean to Early Proterozoic high-grade metamorphic rocks, which historically have been Zhang et al. 1995), showing the distribution of selected gold deposits and major structures. The insert shows the location of the western Qinling belt in the Qinling-Dabie-Sulu (QDS) orogen. ...
Gold deposits of the western Qinling belt occur within the western part of the Qinling-Dabie-Sulu orogen, which is located between the Precambrian North China and Yangtze cratons and east of the Songpan-Ganzi basin. The early Paleozoic to early Mesozoic orogen can be divided into northern, central, and southern zones, separated by the Shangdan and Lixian-Shanyang thrust fault systems. The northern zone consists of an early Paleozoic arc accreted to the North China craton by ca. 450 Ma. The central zone, which contains numerous orogenic gold deposits, is dominated by clastic rocks formed in a late Paleozoic basin between the converging cratonic blocks. The southern zone is characterized by the easternmost exposure of Triassic sedimentary rocks of the Songpan-Ganzi basin. These Early to Late Triassic turbidities, in part calcareous, of the immense Songpan-Ganzi basin also border the western Qinling belt to the west. Carlin-like gold deposits are abundant (1) along a westward extension of the southern zone defined by a window of early Paleozoic clastic rocks extending into the basin, and (2) within the easternmost margin of the basinal rocks to the south of the extension, and in adjacent cover rocks of the Yangtze craton. Triassic and Early Jurassic synkinematic granitoids are widespread across the western Qinling belt, as well as in the Songpan-Ganzi basin. Orogenic lode gold deposits along brittle-ductile shear zones occur within greenschist-facies, highly-deformed, Devonian and younger clastic rocks of the central zone. Mainly coarse-grained gold, along with pyrite, pyrrhotite, arsenopyrite, and minor base metal sulfides, occur in networks of quartz veinlets, brecciated wall rock, and are disseminated in altered wall rock. Isotopic dates suggest that the deposits formed during the Late Triassic to Middle Jurassic as the leading edge of the Yangtze craton was thrust beneath rocks of the western Qinling belt. Many gold-bearing placers are distributed along the river systems that flow south from the lode-bearing central zone. Carlin-like gold deposits have only been identified during the last decade in the southern zone of the western Qinling and in the northeastern corner of the Songpan-Ganzi basin. The deposits mainly contain micron-diameter gold in arsenical pyrite; are characterized by the common occurrence of cinnabar, stibnite, realgar, and orpiment; exhibit strong silicification, carbonatization, pyritization, and decalcification dissolution textures; and are structurally controlled. The lack of reactive host lithologies may have prevented development of large (>100 tonnes of gold), stratigraphically-controlled orebodies, which are typical of the Carlin deposits in the western USA. These deposits are hosted by Triassic turbidities and shallow-water carbonates, and an early Paleozoic inlier in the Songpan-Ganzi basin that extends in an east-west belt for about 300 km. Rather than true "Carlin" deposits, these Carlin-like deposits may be some type of shallow-crustal (i.e., epithermal) hybrid with features intermediate to Nevada-style Carlin deposits and the orogenic gold deposits to the immediate north. These Carlin-like deposits also overlap in age with the early Mesozoic orogenic gold deposits and, therefore, also formed during the final stages of collision between the cratons and intermediate basin closure.
... The study area is located in the southern edge of Qin-ba Mountain Region (Fig. 1a, b) in Shaanxi Province, in which is characterized by a complicated geological environment. From the point of view in the paleotectonic framework, the area belongs to Da-ba arc-shaped fault belt between South Qinling orogen and North Yangtze platform due to historical intense tectonic activities at the center of China (Zhang et al. 1995). A series of thrust nappe faults and wrinkles extending towards direction of NW-SE have been Fig. 1 a, identified in the Da-ba fault belt, leading to the fractured rock mass constituting the Northern Da-ba mountain range. ...
A combined field hydrological monitoring and hydro-mechanical numerical investigation into the triggering mechanism in rainfall-induced shallow landslides was proposed and carried out in the Ren River catchment of central China, considering the effect of predisposing geological conditions. Based on the seasonal monitored data of shallow soils, hydrological behaviors of the slope were obtained and it facilitates the development of conceptual hydrological models. A calibrated hydrological model was then obtained by comparing the event-based results of both the monitored and simulated variation in soil water content/pore pressure. Then, this calibrated hydrological model was extended to reconstruct a seasonal hydrological regime and the corresponding triggering condition of a shallow landslide on the monitored slope in 2010. Local geomorphological and stratigraphic features of the slopes affected by shallow landslides in the Ren River catchment were considered as predi-posing factors to impact hydrological behaviors and the corresponding triggering mechanism of a shallow landslide. Additional slope cases with distinctive slope topography and stratigraphic features were reconstructed to carry out seasonal hydrological response modelling and local slope stability analysis. Results indicate that the decreasing matric suction in response to rainfall infiltration at shallow depth is the main trigger for those landslides on planar and concave slopes with relatively thick soil mantle. A stratigraphic discontinuity that the presence of a steep rock scrap leads to the pinching out of a soil layer on a convex slope, narrows the drainage channel and possibly leads to a significant accumulation of a perched water table. The infinite slope model, considering the evaluated pore pressure at different depths and local geological conditions can be effectively applied to reconstruct the shallow landslide occurrences during the rainstorm event in 2010.
... Qinling orogenic belt was formed by the collision between the North and South China blocks (Meng & Zhang, 1999;Sun et al., 2002;Zhang, Meng, & Lai, 1995;Zhang, Xiang, & Meng, 1995 (Meng & Zhang, 2000;Zhang et al., 2004;Zhang, Meng, & Lai, 1995). The Shangdan Suture resulted from Middle Palaeozoic collision of the North China Block and the South Qinling (Meng & Zhang, 1999). ...
The Sanshilipu monzogranites is located in the northern margin of the South Qinling Block, with an outcrop of about 10 km², and as an intrusion into Palaeozoic Danfeng ophiolitic mélange. The samples consist mainly of plagioclase, K‐feldspar, quartz, biotite, and minor titanite, apatite, magnetite, with contents of SiO2 (61.73–68.49%), Al2O3 (14.58–16.61%), K2O + Na2O (5.79–8.87%), MgO (1.07–2.91%), and low TiO2 (0.55–0.83%), similar to those of I‐type granite. They also show high concentrations of LREE, Pb, and Sr, slightly negative Eu, but low HREE, Nb, Ta, and Y. High Sr and Sr/Y, low Y characteristics are similar to those of adakite. High precision LA‐ICP‐MS U–Pb dating and trace element analysis of zircon in the Sanshilipu granite yielded a concordant age of 205 ± 1 Ma. This age is apparently younger than the closure age of the Mian‐Lue Ocean (242–221 Ma). We propose that the Sanshilipu monzogranites formed by magma mixing of thickened lower crust and limited mantle‐derived mafic magma during post‐collision of the South China and North China blocks.
... The South China Craton, one of the largest continental blocks in China (along with the Tarim Craton and North China Craton), has been considered to be a key element in the Rodinia supercontinent (Huang, 1977;Zhang et al., 1995Zhang et al., , 1996Zhang et al., , 2004. It is separated from the North China Craton by the Qinling-Dabie-Sulu orogeny in the north, from the Indochina block by the Ailaoshan-Song Ma suture zone in the southwest, and from the Songpan-Gantze terrane by the Longmenshan fault in the northwest, and it is bounded by the Pacific Ocean to the southeast (Fig. 2a, inset). ...
Fracture geometry in folded strata is fundamental to stress and strain analysis and outcrop reservoir analogues. The well-exposed Tian'mu anticline, which consists of interlayered micrite limestone and cherty limestone, was studied in order to reveal interlayer slip mechanisms, and stress and strain impacts of derived fractures and minor folds by using Terrestrial Laser Scanning LiDAR data. The minor folds, occurring predominantly within flexible micrite limestone layers, are closely related to interlayer slip and are largely affected by the lithology. The secondary structures were probably formed at different times during past folding processes. It is necessary to separate different joint sets and secondary folds, and to then judge their ages separately. This results in implications for joint research. More importantly, it is necessary to consider the overall strain of the primary fold, or a larger area when researching the strain variations.
... There are five provenance regions that control the detrital minerals in the Yan-Chang #7 Member ( Figure 4c): the northeast and southwest of the basin are the primary sediment source regions, and the northwest, west and south of the basin are secondary sediment source regions (e.g. Jiang, 1988;Liu, Ke, Wu, & Huang, 1997;Mattauer et al., 1985;Peltzer, Tapponnier, Zhitao, & Qin, 1985;Yan et al., 2007) (Figure 1; Zhang, Xiang, & Meng, 1995). ...
The Chang 7 Member of the Yan-Chang Formation (Yan-Chang #7 Member), which is located in the central south of the Ordos Basin (China), is assessed for its potential as a shale gas resource. The characteristics and spatial variability of mineral components in this continental shale formation play a crucial role in evaluating and characterising the shale reservoirs. We collected 64 shale core samples from 30 representative sampling sites located in the central south of the Ordos Basin using X-ray diffraction and field emission scanning electron microscopy to study the mineral compositions, vertical/planar variations of minerals, and the major controlling factors that result in such variations. Based on the relative fractions of the dominant minerals, the shale rocks can be classified into four categories: quartz-rich (type #1), illite/chlorite-rich (type #2), illite–smectite mixed-layer-rich (type #3) and feldspar-rich (type #4). In general, type #1 is mainly located in the northwest of the study area, type #4 is mainly located in the south of the study area, and types #2 and #3 are sandwiched between types #1 and #4. In the centre of the basin, the illite content increases with burial depth and the conversion from smectite to illite, which is experimentally confirmed in this study, enhances the surface porosity of shale. The major factors influencing the properties and spatial variability of the mineral components include sedimentary environment, provenance and diagenesis. Compared with marine shales in China (e.g. Longmaxi marine shales), the Yan-Chang #7 Member continental shale has a higher clay content, but lower calcite, dolomite and pyrite contents. The brittleness indexes of type #1 shale in Wuqi and its surrounding areas are marginally higher than that of Longmaxi marine shales, which makes the type #1 shale in the Wuqi and its surrounding areas slightly easier to fracture than the Longmaxi marine shales.
... All of the Late Mesozoic granitic rocks in the Qinling-Dabie Mo belt plot in the post-collisional tectonic field of a Rb versus (Y+Nb) discrimination diagram (Fig. 6) (Pearce, 1996;Pearce et al., 1984), which is consistent with the tectonic evolution of the Qinling-Dabie orogenic belt (e.g., Wu and Zheng, 2013;Zhang et al., 1995). Whole rock Sm-Nd isotope compositions of the Late Mesozoic granitic rocks, which are characterized by very low Nd (t) values varying mainly in the range of -10 to -20, suggest a crustal origin (Table S3) Mo belt have Hf (t) ranging between -10 and -30 (Table S4), which plot above the 2.0 Ga evolution line of average crust ( 176 Lu/ 177 Hf = 0.015) (Griffin et al., 2002), suggesting that the granitic rocks were mainly derived from re-melting of crustal materials with two-stage Hf model ages younger than 2.0 Ga (Fig. 8). ...
The Qinling–Dabie orogenic belt is the most important molybdenum ore belt in the world, with a proven reserve of over 9 million tons metal Mo. More than 92% of the reserves come from porphyry (-skarn) type deposits that are closely related to Late Mesozoic granite intrusions (158–101 Ma) occurring mainly along the southern margin of the North China Craton, where the majority of the continental crust was formed before 2.5 Ga with crustal Hf model ages of 2.8 to 3.2 Ga. The granite intrusions, which consist mainly of granodiorite, monzogranite, and syenogranite, intrude an Archean to Paleoproterozoic basement. The granitic rocks are metaluminous to peraluminous with C/CNK values mostly in range of 0.9–1.2, commonly alkaline rich with high-K calc-alkaline and shoshonitic features. The linear trends of major and trace elements on Harker diagrams suggest a common magma source for the granitic rocks. Abundant inherited zircons with Neoproterozoic U–Pb ages and substantial younger crustal Hf model ages (averaging 2.4 Ga and 2.0 Ga for granitic rocks with U–Pb ages older and younger than 125 Ma, respectively) demonstrate that these granitic rocks were probably derived from partial melting of the subducted northern Yangtze continental crust with Hf model age younger than 2.2 Ga. Integrating the recent progresses in geological, geochronological, and geophysical investigations of the Qinling–Dabie orogenic belt, we propose that it is the conjunction of the decoupling of the subducted plate at the easternmost part and the slab rollback and subsequent breakoff at the westernmost part of the orogenic belt that resulted in the westward shallowing continental subduction along the Manlue suture at the southern margin of the Qinling–Dabie orogenic belt. This subduction took place during westward propagating continental collision in the Late Triassic and the prolonged relative rotation of the North China Craton and Yangtze Block that lasted until the Middle Jurassic.
... Before the large-scale uplifting denudation, the reservoir temperature was above 200 o C, and hydrocarbons had completely turned into natural gas. At the late Yanshanian-early Himalayan period, owing to the subduction of paleo-Pacific plate, the Qinling orogenic belt compressed southwards and resulted in a clockwise rotation of the Sichuan Basin (Zhang et al.,1995). Thus, the NE Sichuan Basin was subjected to the intensive compression from the northwestern direction, and the great uplift of the Dongyuezhai structure caused the reversal of the highest and lowest positions and the north-south difference in height was about 600m, and a seesaw-type structural hinge was formed. ...
Taking the geology and tectonic evolution characteristics of the Sichuan Basin into account, the chemical and stable isotopic compositions of natural gas, and biomarker compounds in the reservoir bitumen in the Puguang giant gas field, are investigated to identify the genetic type of marine sour natural gas, take the gas-source correlation, and set up the gas-filling model of the Puguang giant gas field in the Sichuan Basin. The alkane gases in the field are dominated by methane, ranging from 22.06% to 99.64% with an average value of 76.52%, and the low content of heavy hydrocarbon gases are dominantly ethane and little propane. The H2S contents occur among the marine carbonate gas reservoirs, ranging from 0 to 62.17%, wherein the H2S contents in the Upper Permian Changxing Formation and Lower Triassic Feixianguan Formation range from 6.9% to 34.72% (average value=15.27%) and from 0% to 62.17% (average value= 13.4%), respectively, indicating that both are H2S-enriched reservoirs. The chemical and carbon isotopic compositions of marine natural gases show that the alkane gas in the Puguang giant gas field is dominantly oil-cracking gas at high maturity stage, and the biomarker characteristics of reservoir bitumen indicate that the major source rocks are the Upper Permian Longtan Formation sapropelic matters. Moreover, various levels of thermochemical sulfate reduction (TSR) were present in the process of oil-gas transformation, not only increasing the content of non-hydrocarbon gas components (CO2</ sub> and H2S) and decreasing the content of heavy hydrocarbon gases, but also causing the reversal of carbon isotope compositions of methane and ethane and the heavier carbon isotope of methane. The recovery of structural configurations over geological time investigates that the gas-filling history of Puguang giant gas field can be divided into three stages: formation of paleo-oil accumulation from the middle-late Indosinian period to the early Yanshanian period, thermal cracking of paleo-oil and TSR alteration from the early to the middle Yanshanian period, and adjustment of gas accumulation from the late Yanshanian to the early Himalayan period. The gypsum of the Lower Triassic Jianglingjiang Formation and the Middle Triassic Leikoupo Formation plays the most important role as effective seal to the gas preservation in different periods.
... The Qinling orogen was built up through the Middle Paleozoic collision of the North China and South Qinling Blocks along the Shangdan suture (SDS), and the Middle-Late Triassic collision of the South Qinling and South China Blocks along the Mianlue suture (MLS) (Fig. 1b) (Zhang et al., 1989). The Qinling orogen can be divided into the East and West segments by the Foping Dome (Zhang et al., 1995a(Zhang et al., , 1995b. ...
... It is not clear exactly where is the suture boundary between the Yangtze and the North China Craton, but near the historical city of Xi'an, a geosuture marked by the Shang-Dan (Shangnan-Danfeng) fault, possibly defines the southern boundary of the Qinling Orogen (inset B of Fig. 1). Details of the geodynamic evolution of the Qinling Orogen can be found in Zhang et al. (1995), Meng and Zhang (2000) and Ratschbacher et al. (2003). As mentioned above, the Qinling Orogen was built during collision processes that sutured the Yangtze Craton with the North China Craton, at about 450 Ma, when the intervening Shang Dan Ocean closed, followed by the opening of the Mian-Lue Ocean splitting the northern margin of the Yangtze Craton. ...
journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues. Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. In most cases authors are permitted to post their version of the article (e.g. in Word or Tex form) to their personal website or institutional repository. Authors requiring further information regarding Elsevier's archiving and manuscript policies are encouraged to visit: http://www.elsevier.com/copyright Author's personal copy Isotope systematics and fluid inclusion studies of the Qiyugou breccia pipe-hosted gold deposit, Qinling Orogen, Henan province, China: The Qiyugou gold deposits, Henan Province, are hosted in breccia pipes within the Xiong'er terrane (Qinling Orogen), on the southern margin of the North China Craton. In these deposits three paragenetic assemblages have been recognized: an early K-feldspar–epidote–quartz–pyrite; a middle quartz-polymetallic sulfide; and a late quartz–carbonate ± adularia. In this paper we review and interpret fluid inclusion and stable and radiogenic isotopic data of host rocks and ores. Fluid inclusions in quartz and calcite include water-rich, CO 2 -rich, and daughter crystal-bearing. The CO 2 -rich and daughter mineral-bearing fluid inclusions are common in the early-stage quartz and absent in the late-stage quartz and calcite which only contain water-rich fluid inclusions. Accordingly, the early-stage ore-fluids are magmatic in origin and characterized by high-temperature (N 350 °C), high-salinity (N 30 wt.% NaCl equiv.), and are CO 2 -rich. Fluid-boiling in the middle ore stage resulted in CO 2 -release, decreasing oxygen fugacity and rapid precipitation of ore materials. The late stage fluids, have low-temperature, low-salinity, are CO 2 -poor and lack daughter minerals. These fluids are probably sourced from meteoric water. H–O–C isotope systematics confirm that, the ore–fluid system evolved from magmatic to meteoric. The carbon and lead isotope ratios indicate that the Meso-Neoproterozoic sequence south of the Xiong'er terrane was the likely source of the ore-forming materials. The Qiyugou breccia-pipes and their associated gold ores were emplaced during an extensional regime following a transition from collision to rifting tectonics, linked to collision and subduction of the Yangtze plate beneath the North China Craton. Geochronological studies show that Mesozoic magmatism in the region occurred between the Triassic and Cretaceous. The Triassic to Jurassic magmas were mostly derived from partial melting of ancient crust, whereas the Cretaceous magmas show juvenile signatures, indicating mantle-derived components. Processes of fragmentation of lithospheric roots, crustal and lithospheric thinning, extension and rifting were probably associated with the subducting Pacific (Izanagi) plate. These crust–mantle geodynamic processes were responsible for the development of anorogenic granitic melts that interacted with the Meso-Neoproterozoic volatile-rich sedimentary successions, producing a flow of gas-rich hydrothermal fluids that resulted in the emplacement of the Qiyugou auriferous breccia pipes. We conclude that the Qiyugou gold deposits are intrusion-related explosive breccia pipe-type that evolved from hypothermal through mesothermal to epithermal.
... Before the large-scale uplifting denudation, the reservoir temperature was above 200 o C, and hydrocarbons had completely turned into natural gas. At the late Yanshanian-early Himalayan period, owing to the subduction of paleo-Pacific plate, the Qinling orogenic belt compressed southwards and resulted in a clockwise rotation of the Sichuan Basin (Zhang et al.,1995). Thus, the NE Sichuan Basin was subjected to the intensive compression from the northwestern direction, and the great uplift of the Dongyuezhai structure caused the reversal of the highest and lowest positions and the north-south difference in height was about 600m, and a seesaw-type structural hinge was formed. ...
... These data support the idea of a multiphase history for the Indosinian orogeny of Indochina (Hahn, 1984). In China, Indosinian shear movements of Middle Triassic age formed in the Qinling-Dabie orogenic belt as a result of a final oblique interaction between the Qinling plate and the Yangtze and North China blocks (Mattauer et al., 1991;Zhang et al., 1995); they have also been recognized in the Ogcheon belt of Korea (Cluzel et al., 1991). ...
Several NW-trending ductile and partly mylonitic shear zones cross the Truong Son belt of Central Vietnam, along the Song Ma and Song Ca valleys and, north of the Kontum block, from Da Nang to Aluoi and Khe Sanh. High-grade metamorphic rocks of amphibolite facies, showing a retrograde evolution and consisting of ortho- and paragneisses, metavolcanics, amphibolites, marbles and quartzites are exposed along these structures. They display a homogeneous deformation pattern characterized by a generally steeply dipping foliation and a near-horizontal to gently plunging mineral stretching lineation, indicating a strike-slip tectonic regime of deformation. Along the southernmost fault zone at least, various and consistent kinematic indicators, including SC structures, asymmetric tails of porphyroclasts, prove that the strain and metamorphism have been generated by a phase of dominantly non-coaxial deformation with a dextral sense of shear. 40Ar39Ar dating, applied on the high-grade metamorphic rocks minerals occurring along these zones, provide plateau cooling ages, closely around 245 Ma, establishing that this event took place in the lowermost Triassic as an early phase of the Indosinian orogeny. The existence of Indosinian movements in Vietnam, as they have been defined by previous authors during the early century, is now accurately confirmed and this is the first insight in the occurrence of ductile strike-slip tectonics of Indosinian age along NW-SE fault zones. Well-expressed in Central Vietnam is a Cretaceous thermal and deformational overprint, marked by epimetamorphism, which took place between 90 and 120 Ma, as attested by low-temperature degassing ages. This Cretaceous event is not found further north in the Song Ma zone where younger ages appear as a result of the influence of Cenozoic shear movements along the Red River fault which displays 20–30 Ma ages. On the northern flank of Song Ca, in the Bu Khang-Phu Hoat core complex, comparable Oligocene-Lower Miocene ages (20–35 Ma), yielded by biotite and phlogopite, reflect a strong overprinting and attest to a rapid uplift of the basement.
... On the western side, in the region of Helanshan (locality 14, Fig. 2), thick platform-margin and basinal facies were deposited. The southern margin of the platform is bounded by another major fault and suture zone (the Middle Tectonic Belt of Kunlun-Qilian-Qin Ling, Fig. 2) and here the Qin Ling foldbelt is composed of thick lower Palaeozoic basinal sediments and volcanics (Zhang et al., 1995(Zhang et al., , 1996. Subduction here was directed northwards. ...
The Cambro-Ordovician strata in North China were deposited over a very extensive craton, extending some 1500 km east-west and 1000 km north-south. The dominantly shallow-water carbonate succession reaches up to 2000 m in thickness and two megasequences (transgressive-regressive cycles) can be distinguished: Lower Cambrian through Lower Ordovician strata, and Middle through Upper Ordovician strata, separated by a major palaeokarst. The first megasequence consists of nine sequences which are generally 50-150 m in thickness. The Lower Cambrian sediments consist of phosphorites and phosphatic sandstones, deposited during the flooding of the craton. Carbonates, mudrocks and evaporites were deposited in the Early Cambrian under an arid climate, laying the foundation for the subsequent long period of shallow-water carbonate deposition which lasted some 70 m.y. The Middle and lower Upper Cambrian sequences consist predominantly of mudrocks and storm deposits (‘tempestites’) in the lower part and oolitic grainstones and tidal-flat lime mudstones in the upper part; these represent outer-mid and mid-inner-ramp depositional systems, respectively, of the transgressive and highstand systems tracts. These sequences have strong similarities with the ‘Grand Cycles’ in the Cambro-Ordovician successions of North America. In the Upper Cambrian, there is a distinctive unit of glauconitic purple-red mudstone several metres thick which is interpreted as the deposits of the maximum flooding of the first megasequence. In the Upper Cambrian, there was a phase of tilting of the North China Carbonate Platform to the north, and storm deposits, especially intraclastic conglomerates and hummocky cross-stratified grainstones-packstones, were very common at this time. Also common in upper Middle and lower Upper Cambrian strata are stromatolitic-thrombolitic bioherms, several metres in diameter. The upper Upper Cambrian through Lower Ordovician strata are dominantly fine-grained limestones and dolomites deposited in shallow-subtidal and inter- to supra-tidal environments on a low-energy epeiric-sea platform. This part of the succession is the regressive part of the first megasequence, so that overall the platform shows an evolution from platform initiation to platform foundation, to a ramp-depositional system and then an extensive epeiric platform. On a small scale, the succession is composed of metre-scale shallowing-upward cycles (parasequences) arranged into cycle sets of 10–30 m thick. The Middle-Upper Ordovician megasequence consists mostly of shallow-water carbonates with several thick evaporite units. Minor palaeokarsts and palaeosoils separate the sequences, which are composed of metre-scale cycles. Regional uplift affected the North China Platform in the Ordovician and sedimentation did not resume until the Carboniferous. There is a good correlation of the two transgressive-regressive megasequences described here with the global 2nd-order relative sea-level curve for the Cambro-Ordovician.
... These data support the idea of a multiphase history for the Indosinian orogeny of Indochina (Hahn, 1984). In China, Indosinian shear movements of Middle Triassic age formed in the Qinling-Dabie orogenic belt as a result of a final oblique interaction between the Qinling plate and the Yangtze and North China blocks (Mattauer et al., 1991;Zhang et al., 1995); they have also been recognized in the Ogcheon belt of Korea (Cluzel et al., 1991). ...
New structural field data at various scale and 40Ar–39Ar geochronological results, from the basement rocks in the Truong Son belt and Kontum Massif of Vietnam, confirm that ductile deformation and high-temperature metamorphism were caused by the Early Triassic event of the Indosinian Orogeny in the range of 250–240 Ma. A compilation of isotopic data obtained in other countries along the Sibumasu–Indochina boundary broadly indicates same interval of ages. This tectonothermal event is interpreted as the result of a synchronous oblique collision of Indochina with both Sibumasu and South China, inducing dextral and sinistral shearing along E–W to NW–SE and N–S fault zones, respectively. The collision along Song Ma follows the northwards subduction of Indochina beneath South China and the subsequent development of the Song Da zone which in turn was affected by the Late Triassic Indosinian phase of shortening. Within the Indochina plate, internal collisions occurred coevally in the Early Triassic, as along the Poko suture, at the western border of the Kontum Massif.
To reveal the influence mechanism of volcano on lacustrine organic matter enrichment, this paper, taking the Yanchang Formation in the Ordos Basin as an example, systematically analyzed the geochemical characteristics of source rocks, and found that black shale was affected by climate event caused by volcano. However, organic matter enrichment is not synchronous with volcanic eruption in time, but has “hysteresis” effect. The evidence of volcanic activity mainly includes two aspects: one is large amount of volcanic ash in black shale, and the other is negative shift of organic carbon isotope. The volcanic ash was airborne, which came from the southern Qinling Orogenic Belt. Because the volcano eruption occurred on land, the negative shift of organic carbon isotope reached −2‰. The climate event caused by volcano has three effects on organic matter enrichment in black shale: first, it brought nutrients for the growth of organisms and released a large amount of greenhouse gases such as CO 2 to accelerate photosynthesis and promote the growth of organisms; second, a large amount of toxic gases such as SO 2 and H 2 S were released and O 2 was consumed and diluted in the air, forming a severe anoxic environment and accelerating the preservation of organic matter; third, it caused extremely hot weather, resulting in long-time surface runoff and other climate events, increasing input of terrestrial organic matter, and forming light components of hydrocarbons.
The main purpose of this three-part review Is to summarise and evaluate geological and palaeomagnetic constraints on the former location and dispersal of continental fragments that are believed to have formed part of the northern margin of Greater Australia, sometime during the Phanerozoic. The emphasis is on identification of fragments that were adjacent to Australia's northwestern margin and on their
dispersal in relation to its Phanerozoic evolution. The search for such former fragments has been wide, and geographically covers the whole of Asia east of the Urals and terranes In the North American Cordillera.
The review is presented In three parts: (i) a regional, in part historical, overview of hypotheses on the fragmentation of Greater Australia/eastern Gondwana and subsequent accretion of disrupted terranes to the Siberian and North American cratons (this Record 1996/51); ii) computation of available Phanerozoic palaeomagnetic constraints for the main dispersive Gondwanan fragments - Australia and India, the main accretionary craton - Siberia, and all terranes of suspected Gondwanan origin in Asia east of the Urals and in the North American Cordillera. These data are interpreted in terms of palaeolatitudinal evoIutions, times of fragmentations, and palinspastic reconstructions, culminating into
an integrated Interpretation of the palaeomagnetic findings in terms of regional evolution of Australia's North West Shelf, as known from available literature and established so far from AGSO's North West Shelf project (Record 1996/52 • Klootwijk 1996a); and iii) documentation of all available relevant palaeomagnetic results (Record 1996/53 - Klootwijk 1996b).
The Qinling orogen was formed as a result of the collision between the North and South China blocks. The Qinling orogen represents the location at which the southern and northern parts of the Chinese mainland collided, and it’s also the intersection of the Central China orogen and the north-south tectonic belt. There is evidence of strong deformation in this orogen, and it has had a long and complex geological history. We investigated the structure of the Moho in the southern Qinling orogen using large dynamite shot imaging techniques. By integrating the analysis of the single-shot and the move-out corrections profile, we determined the structure of the Moho beneath the northern Dabashan thrust belt and the southern Qinling orogen, including the mantle suture beneath Fenghuang mountain. The Moho is divided into two parts by the mantle suture zone beneath Fenghuang mountain: (1) from Ziyang to Hanyin, the north-dipping Moho is at about 45–55 km depth and the depth increases rapidly; and (2) from Hanyin to Ningshan, the south-dipping Moho is at about 40–45 km depth and shallows slowly. The mantle suture is located beneath Fenghuang mountain, and the Moho overlaps at this location: the shallower Moho is connected to the northern part of China, and the deeper Moho is connected to the southern part. This may indicate that the lithosphere in the Sichuan basin subducts to the Qinling block and that the subduction frontier reaches at least as far as Fenghuang mountain.
A study was made of the principal features of the tectonics and evolution of the Mongolian-Okhotsk and Qinling fold-thrust systems, clamped between the Aldan-Stanovoi and North China and South China (Yangtze) geoblocks, respectively. A repeated intermittence of tension and strike-slip processes is established in them. The stability of the Boreal biogeographical province in the Middle and Late Paleozoic is emphasized and the terrain model for the Mongolian-Okhotsk system is put in doubt.
Based on research on petrology, mineralogy, petrochemistry, geochemistry, and REE for albite carbonate brecciaite, geological and geochemical characteristic of albite carbonate brecciaites from Ertaizi copper-gold deposits in the Qinling orogen have been discussed in the paper. From Late Devonian epoch to Carboniferous period, under tectonic formation of regional penetration of Mantle feather, hydrothermal fluids in depth upward alone pre-existing tectonic feeder and poured into Ertaizi hydrothermal subbasin on the sea bed, so hydrothermal sedimentary rocks were formed and were controlled by synsedimentary faults and strata. These rocks which were main parts of gold source layer with gold mineralization consist of quartz barite carbonate breccia, carbonate breccia, poly-component breccia, albite, albite carbonate rock. In Yanshanian movement, in the intersections of NE trending fault, NW trending fault and EW trending fault, pre-existing hydrothermal brecciaite were superimposed by hydrothermal fluids which derived from regional penetration of Mantle feather, so albite carbonate breccia in barrel-shaped were formed. Copper-gold deposits hosted in Ertaizi albite carbonate breccia in the Qinling orogen was formed by the same hydrothermal fluid.
The South China Fold Belt, Qinling-Dabie-Sulu, Qilian and Hinggan orogens are reviewed in this chapter. The South China Fold Belt is the coastal part of the Cathaysia Block, which was directly influenced by subduction-related calc-alkaline magmatism in the Jurassic-Cretaceous. During this time mineral deposits of Sn, W, Mo, Pb-Zn, Cu, Sb, hydrothermal vein-type, porphyry Cu-Au, skarns, and precious metal epithermal were formed. The Zhilingtou and Huangshan epithermal deposits are reviewed, followed by Au-Cu high-sulphidation epithermal mineralisation in the Zijinshan mining district (Fujian Province) and the polymetallic Ag-rich and low-sulphidation veins and/or stockworks of the Coastal Volcanic Belt. Chinkuashih is the youngest (1 Ma) epithermal system in the northern tip of Taiwan and part of the western extension of the active Ryukyu volcanic arc.
The west-northwest-trending Qinling fold belt in central China lies in Sichuan, Gansu,
and Shaanxi Provinces. It is a long-lived mobile belt between the Huabei (North China) and
Yangtze Precambrian cratons. The 750–km-long and about 200–km-wide fold belt contains
several groups of epigenetic, stratabound, and tectonized sedimentary rock-hosted Au deposits
that are hosted in deformed and folded late Paleozoic to early Mesozoic sedimentary and
volcanoclastic rocks. The eastern parts of the Qinling fold belt contain Carlin-type and
syndeformational sedimentary rock-hosted Au deposits, and the west parts of the belt contain
mainly Carlin-type deposits in north Sichuan and south Gansu Provinces. In addition a cluster of
deposits are present along the Luhuo-Daofu fault zone to the west of these deposits.
Sedimentary rocks in the Qinling fold belt are folded in east-west-oriented fold zones that
contain low-grade metamorphic rocks, which are composed of calcareous sandstone, chert,
siltstone, interbedded micritic limestone, carbonaceous and calcareous slate, and local mafic
volcanic units. Widespread magmatic activity in the Qinling fold belt resulted in emplacement
of Paleozoic and Mesozoic geochemically intermediate composition stocks and plutons. Igneous
rocks are not consistently spatially associated with most of the sedimentary rock-hosted Au
deposits, although some deposits are hosted in dikes or in contact metamorphic zones and some
of the deposits may have genetic associations with the intrusive rocks.
Geochemical elements anomalous in the deposits are Au, Hg, Sb, and Ag, with less
consistently high concentrations of Tl, U, and W. Mercury and Sb deposits are widely
distributed in Devonian and Carboniferous strata and Au is associated with some of these
deposits. Ages of the deposits are poorly constrained and may be any time within the
Phanerozoic. Alteration and mineralogy of the gangue minerals and ores in most Carlin-type Au
deposits in the Qinling fold belt include illite and quartz, local carbonation, decarbonatization,
and many typical sulfide assemblages such as pyrite, arsenical pyrite, As sulfide mineral and
stibnite. Realgar and orpiment are abundant in many of the deposits, particularly in the West
Qinling fold belt. Some minerals and elements not normally common to Carlin-type sedimentary
rock-hosted A deposits locally are present in some deposits in the Qinling fold belt, such as
scheelite, U, Ti, and PGE minerals.
The crustal structure of the Tibetan Plateau records the dynamic processes of several terranes that underwent disaggregation, aggregation, and amalgamation. The dynamic evolution of continental crusts is best understood from these three processes. However, the detailed geochemical province division of the Tibetan Plateau and the palaeo-tectonic affinity or evolution of terranes remains unclear. In this paper, the acid-insoluble fraction of fine-grained river sediments from catchments in the whole Tibetan Plateau was measured for lead isotopes and trace elements. This study aims to reveal lead isotopic characteristics, to delineate different lead isotope geochemical provinces, and to trace and uncover the tectonic affinities of various terranes in the Tibetan Plateau. Results show that by weak acid chemical treatment, the characteristics of the Pb isotopes of fine-grained river sediments can be utilized to represent and discriminate geochemical provinces. The characteristics of Pb isotopes enable the identification of different geochemical provinces and the palaeo-affinity of various tectonic units. Constrained by tectonic evolution, the Tibetan Plateau tectonic units can be divided into the following five Pb isotope geochemical provinces: 1) Qilian Terrane; 2) Northern Tibetan Plateau geochemical province, including Eastern Kunlun-Qaidam, Songpan-Ganzi and Eastern Qiangtang Terrane; 3) Northern Lhasa Terrane; 4) Southern Lhasa Terrane, and 5) Himalaya Terrane. In relation to the controversy concerning the palaeo-affinity of the Qilian and Songpan–Ganzi Terranes, the Pb isotopic compositions of fine-grained river sediments suggest that they were much more likely separated from the Yangtze Craton than from the North China Craton. The characteristics of Pb isotopes and trace elements of the Eastern Kunlun–Qaidam and Eastern Qiangtang Terrane show some similarities with the Songpan–Ganzi Terrane, which indicate that they also possibly originated from the disaggregation of the Yangtze Craton. The various partial melting and contamination of the old Himalaya continental crust from radiogenic Pb isotopes and Tethys mantle materials with low radiogenic Pb isotopes caused different Pb isotopes and trace elemental associations in the Southern and Northern Lhasa Terranes. These factors also led to the evolution of the two different geochemical provinces.
The North China Craton (NCC) is composed of the Eastern and Western Blocks amalgamated along the Central Orogenic Belt (Trans-North China Orogen, TNCO). Geological, geochemical, geochronological and geophysical studies have confirmed that the lithosphere beneath the Eastern Block has undergone significant destruction and modification during the Mesozoic, whereas the Western Block preserves the Archean lithosphere. The mech-anisms and crustal response to the lithospheric disruption remain unclear. Here we construct a lithosphere-scale transect across the Western and Eastern Blocks and the intervening TNCO at the southern margin of the NCC. We interpret the lithosphere thickness, crustal P-wave velocity, density and thermal structure, and also seismic activity. Our results show that: (1) crustal thinning is consistent with lithospheric thinning from west to east of this transect; (2) the seismogenic structure is distinctly different among the Western Block, the TNCO and the Eastern Block; (3) a marked increase in crustal density and average P-wave velocity exists at the contacts between the Western Block and TNCO, and the TNCO and Eastern Block, as well as beneath the Tanlu fault at the eastern margin of the Eastern Block; and (4) a positive correlation is displayed between increasing P-wave velocity (density, temperature) and the occurrence of Mesozoic basalts and high-Mg andesites. Under the tectonic background of the amalgamation pattern between the Eastern and Western Blocks within the NCC, we attribute the lateral variation of crustal geophysical features to the lateral variation of crustal composition or the interaction of mantle flow from the eastward escape from Tibetan collision, and the westward mantle flow beneath the eastern NCC, without excluding the west–east variation of crustal response to lithospheric disruption.
The northwestern part of the Jiaodong Peninsula, or the Zhao-Ye Gold Belt, contains the largest lode-gold deposits in China, which are spatially related to several suites of intrusive granitoids. Previous attempts to provide constraints on the timing of gold mineralization and its tectonic setting, through studies of the granitoids, have led to conflicting data, dependant on the isotopic methodology used, and resultant genetic and tectonic models for their setting are equivocal.SHRIMP U–Pb studies of complexly zoned zircons of the Linglong, Luanjiahe and Guojialing granitoid suites suggest that the Jiaodong Peninsula is underlain by Precambrian basement with components up to 3.4 Ga old. Inherited zircons of early Mesozoic age indicate that this basement was reworked at 250–200 Ma, probably during a collisional orogeny involving the North China Craton and South China Craton. The Linglong, Luanjiahe and Guojialing suites were derived from this early Mesozoic basement between 165 and 125 Ma, and were probably emplaced as post-collisional granitoids, the latest intrusions (at 125 Ma) coinciding broadly with superplume activity or a major plume breakout event in the Palaeo-Pacific Plate.Importantly, if lode-gold mineralization is essentially a single event, as indicated by similar hosting structures and deposit characteristics, it can be dated between about 126 Ma, the age of the youngest granitoid cut by gold-bearing quartz veins, and 120 Ma, the age of one of a swarm of post-mineralization feldspar-porphyry dykes. Thus, as in most other metallogenic provinces which host so-called mesothermal lode-gold deposits, gold mineralization was late in the orogenic cycle, probably late- or post-accretion, and closely followed the emplacement of the latest major plutonic phase in the development of a series of anomalously voluminous granitoid batholiths.
The Songshugou ultramafic massif is located to the north of the Shang‐Dan fault, the Palaeozoic suture between the North and South China blocks. It is the largest Apline‐type ultramafic body in the Qinling orogenic belt of central China, consisting mainly of dunite with a small amount of harzburgite and minor pyroxenite. We present new LA‐ICP‐MS U−Pb dating and trace element results for zircon from two garnet amphibolite samples in the contact metamorphic zone surrounding the massif. One was sampled ∼1 m from the massif, the other ∼5 m away. The studied zircon grains are small, anhedral, and display typical metamorphic characteristics of low Th/U values (
China contains three major Precambrian blocks, the North China, South China and Tarim cratons, separated and sutured by Phanerozoic orogenic belts. The North China Craton (NCC) contains rocks as old as 3.8 Ga, but is dominated by Neoarchean igneous rocks that were formed during two magmatic events at 2.8–2.7 Ga and 2.55–2.50 Ga. The 2.8–2.7 Ga magmatic pulse is considered as a major phase of juvenile crustal growth in the craton, though exposure of these rocks is limited. The 2.55–2.50 Ga rocks make up ∼80% of Archean basement in the NCC, but their rock associations, structural patterns, and metamorphic age and P–T paths in the eastern and western parts (Eastern and Western blocks) are different from those in the central part (Trans-North China Orogen). In the Eastern and Western blocks, the end-Neoarchean rocks are exposed as gneissic domes and dominated by tonalitic–trondhjemitic–granodioritic (TTG) gneisses and mafic to komatiitic rocks that were metamorphosed at ∼2.5 Ga, along anticlockwise P–T paths involving isobaric cooling, that is interpreted to reflect underplating of mantle-derived magmas. In the Trans-North China Orogen, the end-Neoarchean rocks occur as linear structural belts and are composed of arc-related granitoids and volcanic rocks that formed in a supra-subduction zone setting and were metamorphosed at ∼1.85 Ga along a clockwise P–T paths involving isothermal decompression in a continent–continent collisional setting. Although magmatic arc models can explain the origin of the 2.55–2.50 Ga TTG rocks in the Eastern and Western blocks, a mantle plume model is favored because it best explains many other features, including the formation of komatiitic rocks. The 2.55–2.50 Ga rocks and associated Paleoproterozoic rocks in the Trans-North China Orogen exhibit the same structural and metamorphic characteristics that typify continental margin arcs and collisional belts. Spatially, Paleoproterozoic rocks in the NCC are related to collisional assembly of the disparate parts of the Eastern and Western blocks including a ∼1.95 Ga collisional event that led to amalgamation of the Yinshan and Ordos blocks to form the Western Block, which then collided with the Eastern Block to form the Trans-North China Orogen at ∼1.85 Ga. Following the final assembly at ∼1.85 Ga, the interior of the NCC underwent on-going extension, leading to widespread emplacement of 1.80–1.75 Ga mafic dyke swarms, 1.75–1.68 Ga anorthosite–mangerite–granite–rapakivi suites, and deposition of Mesoproterozoic and Neoproterozoic strata. Meanwhile, a large Paleo-Mesoproterozoic volcanic belt (Xiong’er Group) developed on the southern margin of the NCC, and is variously interpreted as an intracontinental rift zone or an Andean-type continental margin arc. In the late Mesoproterozoic, the northern margin of the NCC underwent rifting (Zhaertai-Bayan Obo rift zone), coincident with breakup of the Columbia (Nuna) supercontinent.
Abstract Researches were made of different continental-margin and intraplate basin systems in the Qinling microplate in terms of hydrothermal deposition, geodynamics of basin formation, hydrothermal sedimentary rock facies, syntectonics in the basins, and the styles of ore accumulation in the basins.
The Yindongzi-Daxigou strata-bound barite-siderite, silver-polymetallic deposits discovered in the Qinling orogen are hosted
within flysch facies in a deep-water fault-controlled basin on the passive northern margin of the Qinling microplate. The
orebodies occur in a series of hydrothermal depositional rocks. Mineralization zoning is characterized by Fe-Ba←Ba-Cu← Pb-Ag→Cu-Ag→Pb→Au.
This is obviously a gradational transition mineralization from ventproximal mineralization to more distal mineralization.
In this gradational transition between Chefanggou and Yindongzi, vent-proximal mineralization consists of silver-polymetallic
orebodies (Pb-Ag), which is the center of hydrothermal mineralization. The Chefanggou Ba-Cu ore district in the west and the
Yindongzi Cu-Ag ore district in the east represent vent lateral mineralization. Distal mineralization in the west is represented
by the Daxigou Fe-Ba ore district while distal mineralization in the east is represented by the Pb ore district. Thick massive,
laminated barren albite chert and jasperite, sometimes with minor silver-ploymetallic mineralization of commercial importance,
and pyritization in rocks feature more distal mineralization. Geochemical anomalies of Au-As associations are found in ankerite
phyllite and muddy sandstone. Actually, Au deposits are dominantly controlled by the late brittle-ductile shear zone.
Three end-member granite emplacement mechanisms, host-rock ductile shortening (HRDS), host-rock rigid displacement (HRRD) and magmatic absorption (MA), are identified in this study of the Huichizi pluton. The internal fabrics are mainly flattening types (ν=0.4–0.9) and strain is high (Es=1.0–0.6) near the boundaries and low (Es=0.7–0.30) toward the central parts of the pluton. In the 1.5-km-wide contact aureole, extension (ε) is measured in syn-emplacement deformed veins and the calculated average shortening normal to the sides and tips of the pluton are 1.14 km and 0.74 km, respectively. From this we conclude that the HRDS produced only about 20% space for the present volume of the pluton; the regional HRRD, derived from the uplift by about 8 km of the Qinling group in a flower structure, contributed 19∼32% space. MS, including stoping and material transfer processes, yielded another 37% space. Of this, stoping contributed a minimum of 1% space, estimated from the surface area of 2.8 km2 covered by xenoliths. Transfer processes provided about 36% of the needed space, deduced from the average 64/36 ratio of hybridization of mantle-derived to crustal- (Qinling group) derived magma. The three mechanisms may act nearly simultaneously as a multiple emplacement mechanism; this situation may apply to many other plutons as well.
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