Geochronology of early Mesozoic diabase units in southwestern China: metallogenic and tectonic implications

2018 ◽  
Vol 156 (07) ◽  
pp. 1141-1156 ◽  
Author(s):  
LIANG QIU ◽  
WEN-XIN YANG ◽  
DAN-PING YAN ◽  
MICHAEL L. WELLS ◽  
JUN-TING QIU ◽  
...  
Keyword(s):  
Oxygen Fugacity ◽  
South China ◽  
Hydrothermal Systems ◽  
Early Jurassic ◽  
Detrital Zircons ◽  
South China Block ◽  
Mafic Magmatism ◽  
Clastic Rocks ◽  
Basement Rocks ◽  
Wide Range

AbstractTwo phases of diabase-sill-forming magmatism are recorded within the Badu anticline where magmas were emplaced into upper Palaeozoic carbonates and clastic rocks of the Youjiang fold-and-thrust belt in the SW South China Block, China. Zircons from these diabase units yield weighted mean U–Pb ages of 249.2±2.0 Ma and 187.1±3.3 Ma, and magmatic oxygen fugacity values from ‒20 to ‒6 (average of ‒12, equating to FMQ +5) and ‒20 to ‒10 (average of ‒15, equating to FMQ +2), respectively. These data indicate that the sills were emplaced during Early Triassic and Early Jurassic times. The discovery of c. 250 Ma mafic magmatism in this area was probably related to post-flood-basalt extension associated with the Emeishan mantle plume or rollback of the subducting Palaeo-Tethys slab. The c. 190 Ma diabase sills indicate that the southwestern South China Block records Early Jurassic mafic magmatism and lithospheric extension that was likely associated with a transition from post-collisional to within-plate tectonic regimes. The emplacement of diabase intrusions at depth may have driven hydrothermal systems, enabling the mobilization of elements from sedimentary rocks and causing the formation of a giant epigenetic metallogenic domain. The results indicate that high-oxygen-fugacity materials within basement rocks caused crustal contamination of the magmas, contributing to the wide range of oxygen fugacity conditions recorded by the Au-bearing Badu diabase. In addition, data from inherited xenocrystic zircons within the Badu diabase and detrital zircons from basement rocks suggest that the Neoproterozoic Jiangshao suture extends to the south of the Badu anticline.

scholarly journals New detrital zircon U–Pb insights on the palaeogeographic origin of the central Sanandaj–Sirjan zone, Iran

2021 ◽  
pp. 1-22
Author(s):  
Farzaneh Shakerardakani ◽  
Franz Neubauer ◽  
Xiaoming Liu ◽  
Yunpeng Dong ◽  
Behzad Monfaredi ◽  
...  
Keyword(s):  
South China ◽  
Detrital Zircon ◽  
Sediment Supply ◽  
Detrital Zircons ◽  
South China Block ◽  
The South ◽  
Clastic Rocks ◽  
Gondwana Margin ◽  
Metamorphic Zone ◽  
North Gondwana

Abstract New detrital U–Pb zircon ages from the Sanandaj–Sirjan metamorphic zone in the Zagros orogenic belt allow discussion of models of the late Neoproterozoic to early Palaeozoic plate tectonic evolution and position of the Iranian microcontinent within a global framework. A total of 194 valid age values from 362 zircon grains were obtained from three garnet-micaschist samples. The most abundant detrital zircon population included Ediacaran ages, with the main age peak at 0.60 Ga. Other significant age peaks are at c. 0.64–0.78 Ga, 0.80–0.91 Ga, 0.94–1.1 Ga, 1.8–2.0 Ga and 2.1–2.5 Ga. The various Palaeozoic zircon age peaks could be explained by sediment supply from sources within the Iranian microcontinent. However, Precambrian ages were found, implying a non-Iranian provenance or recycling of upper Ediacaran–Palaeozoic clastic rocks. Trace-element geochemical fingerprints show that most detrital zircons were sourced from continental magmatic settings. In this study, the late Grenvillian age population at c. 0.94–1.1 Ga is used to unravel the palaeogeographic origin of the Sanandaj–Sirjan metamorphic zone. This Grenvillian detrital age population relates to the ‘Gondwana superfan’ sediments, as found in many Gondwana-derived terranes within the European Variscides and Turkish terranes, but also to units further east, e.g. in the South China block. Biogeographic evidence proves that the Iranian microcontinent developed on the same North Gondwana margin extending from the South China block via Iran further to the west.

scholarly journals Precambrian Basement and Late Paleoproterozoic to Mesoproterozoic Tectonic Evolution of the SW Yangtze Block, South China: Constraints from Zircon U–Pb Dating and Hf Isotopes

Minerals ◽  
2018 ◽  
Vol 8 (8) ◽  
pp. 333 ◽  
Author(s):  
Wei Liu ◽  
Xiaoyong Yang ◽  
Shengyuan Shu ◽  
Lei Liu ◽  
Sihua Yuan
Keyword(s):  
South China ◽  
Tectonic Evolution ◽  
Detrital Zircons ◽  
Geochemical Data ◽  
Precambrian Basement ◽  
Yangtze Block ◽  
Two Stage ◽  
Clastic Rocks ◽  
Columbia Supercontinent ◽  
Isotopic Analyses

Zircon U–Pb dating and Hf isotopic analyses are performed on clastic rocks, sedimentary tuff of the Dongchuan Group (DCG), and a diabase, which is an intrusive body from the base of DCG in the SW Yangtze Block. The results provide new constraints on the Precambrian basement and the Late Paleoproterozoic to Mesoproterozoic tectonic evolution of the SW Yangtze Block, South China. DCG has been divided into four formations from the bottom to the top: Yinmin, Luoxue, Heishan, and Qinglongshan. The Yinmin Formation, which represents the oldest rock unit of DCG, was intruded by a diabase dyke. The oldest zircon age of the clastic rocks from the Yinmin Formation is 3654 Ma, with εHf(t) of −3.1 and a two-stage modeled age of 4081 Ma. Another zircon exhibits an age of 2406 Ma, with εHf(t) of −20.1 and a two-stage modeled age of 4152 Ma. These data provide indirect evidence for the residues of the Hadean crustal nuclei in the Yangtze Block. In combination with the published data, the ages of detrital zircons from the Yinmin Formation yielded three peak ages: 1.84, 2.30 and 2.71 Ga. The peaks of 1.84 and 2.71 Ga are global in distribution, and they are best correlated to the collisional accretion of cratons in North America. Moreover, the peak of 1.84 Ga coincides with the convergence of the global Columbia supercontinent. The youngest age of the detrital zircon from the Yinmin Formation was 1710 Ma; the age of the intrusive diabase was 1689 ± 34 Ma, whereas the weighted average age of the sedimentary tuff from the Heishan Formation was 1414 ± 25 Ma. It was presumed that the depositional age for DCG was 1.71–1.41 Ga, which was in accordance with the timing of the breakup of the Columbia supercontinent. At ~1.7 Ga, the geochemical data of the diabase were characterized by E-MORB and the region developed the same period A-type granites. Thus, 1.7 Ga should represent the time of the initial breakup of the Yangtze Block. Furthermore, the Yangtze Block continues to stretch and breakup until ~1.4 Ga, which is characterized by the emergence of oceanic island, deep-sea siliceous rock and flysch, representing the final breakup. In brief, the tectonic evolution of the Yangtze Block during the Late Paleoproterozoic to Mesoproterozoic coincided with the events caused by the convergence and breakup of the Columbia supercontinent, because of which, the Yangtze Block experienced extensive magmatic activity and sedimentary basin development during this period.

A New Model for the Genesis of Carboniferous Mn Ores, Longtou Deposit, South China Block

2021 ◽  
Author(s):  
Fangge Chen ◽  
Peir K. Pufahl ◽  
Qingfei Wang ◽  
Edward J. Matheson ◽  
Brandi M. Shabaga ◽  
...  
Keyword(s):  
South China ◽  
Coastal Upwelling ◽  
Deep Ocean ◽  
South China Block ◽  
Clastic Rocks ◽  
Water Columns ◽  
Resource Exploration ◽  
Carbonate Factory ◽  
Deposit Model ◽  
Mn Ore

Abstract The lower Carboniferous Luzhai and Baping Formations (ca. 359 Ma) of the South China block, Guangxi Province, comprise an ca. 170-m-thick clastic-carbonate succession capped by Mn ore horizons near the town of Longtou. Excellent exposure of the stratigraphic succession provides an unparalleled opportunity to investigate the origin of carbonate-hosted Mn deposits, which are generally understudied. Lithofacies associations suggest inner and middle shelf clastic rocks accumulated with deposition of carbonates on a mesotrophic middle to outer shelf. In the Longtou region, carbonate deposition during marine transgression culminated with the precipitation of high-grade Mn deposits during maximum flooding. Mn ore horizons are composed of amalgamated alabandite-bearing rhodochrosite, Mn calcite, and braunite laminae. Mn carbonates have been largely interpreted as forming in oxic water columns via reduction of Mn oxides by organic matter. However, paragenetic relationships and δ13C values (similar to those of seawater) indicate the Mn carbonates of Longtou were formed during authigenesis by the emplacement of anoxic, Mn-rich water masses on the distal to middle shelf. Such anoxia is interpreted to have shut down the carbonate factory and diminished sedimentation, a prerequisite for the concentration and precipitation of Mn carbonates in pore water. This research supports the notion that areas of the Paleozoic deep ocean were persistently anoxic and periodically tapped by coastal upwelling to produce Mn- and Fe-rich deposits. Application of this emerging ore deposit model to other economically important carbonate-hosted Mn deposits may improve resource exploration.

Detrital zircon geochronology of pre-Cretaceous strata: tectonic implications for the Jiangnan Orogen, South China

2014 ◽  
Vol 151 (6) ◽  
pp. 975-995 ◽  
Author(s):  
JINBAO SU ◽  
SHUWEN DONG ◽  
YUEQIAO ZHANG ◽  
YONG LI ◽  
XUANHUA CHEN ◽  
...  
Keyword(s):  
South China ◽  
North China ◽  
Seismic Profile ◽  
Upper Jurassic ◽  
Detrital Zircons ◽  
South China Block ◽  
Yangtze Block ◽  
The South ◽  
Provenance Data ◽  
Cathaysia Block

AbstractFifteen sandstone samples taken from pre-Cretaceous strata of the Yangtze Block are analysed to constrain the evolution of the South China Block, especially the assembly between the Yangtze and Cathaysia blocks. The results show that the maximum depositional age of the Neoproterozoic Lengjiaxi Group adjacent to the Cathaysia Block isc. 830 Ma, differing from that of the Kunyang and Dahongshan groups (> 960 Ma) on the southwestern margin of the Yangtze Block. The detrital zircons from Palaeozoic samples from the Yangtze Block have similar age populations to those in the Cathaysia Block, and they may originate from the Cathaysia Block according to palaeogeographic, palaeocurrent and former research data. The detrital zircons of Middle–Upper Jurassic sandstones in the southwestern and central Yangtze Block yield dominant age populations at 2.0–1.7 Ga and subordinate groups of 2.6–2.4 Ga, 0.8–0.7 Ga and 0.6–0.4 Ga. The Upper Triassic strata may be derived from the southern Yangtze and North China blocks due to the collisions between the Indosina, South China and North China blocks, whereas the Jurassic sediments may be partly derived from uplift and erosion of the Jiangnan Orogen due to an intracontinental orogeny induced by Pacific subduction towards the Eurasia Plate. The detrital age spectra and provenance data for basement in the South China Block are analysed and compared with each other. The South China Block has affinity with Australia not only in the Columbia supercontinent but also in the Rodinia supercontinent. We infer the existence of an ancient orogen under the western Jiangnan Orogen, which may have occurred during the Columbia age, earlier than the Sibao orogeny. This is supported by seismic profile proof from the SinoProbe.

Reappraisal of the Mesozoic tectonic transition from the Paleo-Tethyan to Paleo-Pacific domains in South China

2021 ◽  
Author(s):  
Chengshi Gan ◽  
Yuzhi Zhang ◽  
Yuejun Wang ◽  
Xin Qian ◽  
Yang Wang
Keyword(s):  
South China ◽  
Middle Jurassic ◽  
Late Jurassic ◽  
Sedimentary Rocks ◽  
Early Jurassic ◽  
Igneous Rocks ◽  
Late Triassic ◽  
Geochemical Data ◽  
South China Block ◽  
Tectonic Transition

The southeastern (SE) South China Block was mainly influenced by the Paleo-Tethyan and Paleo-Pacific dynamic domains during the Mesozoic. The initial timing of the tectonic transition between these two domains in the SE South China Block still remains debated. The transition would affect the nature of the lithosphere and material provenance of sediments, and, therefore, igneous and sedimentary rocks in the area could record such dynamic processes. In this study, published geochronological and geochemical data of the Triassic and Jurassic igneous rocks and detrital zircon data of contemporaneous sedimentary rocks in the SE South China Block were compiled, aiming to provide constraints on the tectonic transition via tracing the spatial-temporal variations in the nature of the lithosphere and sedimentary provenance signals. The compiled results suggest that the magmatic intensity and volume decreased significantly from the Late Triassic to Early−Middle Jurassic, with an obvious magmatic quiescence between them, and increased from the Early−Middle Jurassic to Late Jurassic. The εNd(t) and zircon εHf(t) values of mafic rocks, granitoids, and shoshonitic rocks remarkably increased from the Late Triassic to Early−Middle Jurassic, indicative of variations in the lithospheric mantle and continental crust. Such variations suggest that the initial tectonic transition occurred at the earliest Early Jurassic. Based on the southward paleocurrents from Early Jurassic sandstone, E-W−trending extension of Early−Middle Jurassic mafic and shoshonitic rocks, and similar sedimentary provenances of Late Triassic and Early−Middle Jurassic sedimentary rocks, these features imply that the SE South China Block was not immediately influenced by the Paleo-Pacific domain during the Early−Middle Jurassic. However, from the Early−Middle Jurassic to Late Jurassic and Early Cretaceous, the spatial distribution, geochemical signatures, magmatic intensity, and magmatic volume of igneous rocks and provenance of sedimentary rocks exhibit obvious variations, and the regional fold hinge direction changed from E-W−trending to NE-trending, suggesting significant effects from Paleo-Pacific subduction on the SE South China Block. Thus, the Mesozoic tectonic transition from the Paleo-Tethyan to the Paleo-Pacific dynamic domain in the SE South China Block likely occurred during the Early−Middle Jurassic.

Provenance of the Paleozoic-Mesozoic siliciclastic rocks of the Istanbul Zone: Constraints on the location of the Rheic suture in Turkey

2020 ◽  
Author(s):  
Remziye Akdoğan ◽  
Xiumian Hu ◽  
Aral I. Okay ◽  
Gültekin Topuz
Keyword(s):  
Detrital Zircon ◽  
Lower Devonian ◽  
Early Carboniferous ◽  
Upper Triassic ◽  
Detrital Zircons ◽  
Upper Carboniferous ◽  
Clastic Rocks ◽  
Wide Range ◽  
Nw Turkey ◽  
Upper Silurian

<p>The Istanbul Zone (NW Turkey) is regarded as the eastward elongation of Avalonia in Central Europe. Its Paleozoic stratigraphy is characterized by continuous sedimentation from Early Ordovician to Late Carboniferous. However, the Intra-Pontide Suture between the Istanbul and Sakarya zones is regarded as a Neotethyan Suture representing an oceanic domain of Permo-Triassic to Cretaceous age. Here, we present U-Pb ages and Lu-Hf isotopic compositions of the detrital zircons from the Upper Silurian-Lower Devonian, Upper Carboniferous, Permian and Upper Triassic sandstones of the Istanbul Zone. Detrital zircon ages from the Upper Silurian-Lower Devonian sandstone are dominated by Mesoproterozoic zircons (1950-900 Ma), with subordinate peaks at the latest Neoproterozoic to Silurian and Mid-Archean (2850-2750 Ma) confirming its Avalonian affinity. Detrital zircons from Carboniferous to Triassic sandstones yielded a major peak at Carboniferous-Early Permian (360-270 Ma) and a minor peak at Late Neoproterozoic-Cambrian (700-480 Ma) while Mesoproterozoic zircons become insignificant. The εHf (t) values of the detrital zircon grains from Upper Silurian-Lower Devonian, Upper Carboniferous, and Upper Triassic sandstones exhibit a wide range from -21.3 to +11.7, and over 62% of zircon grains have negative values, suggesting mixing derivation of both mantle and crustal melts. Apart from the Permo-Triassic magmatism, the Istanbul Zone is devoid of Carboniferous igneous and metamorphic events. Therefore, abundant Carboniferous zircons and disappearance of the Mesoproterozoic zircons in the Carboniferous to Upper Triassic clastic rocks of the  Istanbul Zone require juxtaposition with a continental domain similar to the Sakarya and Rhodope‐Strandja zones, which are characterized by widespread Carboniferous magmatism. We suggest that the Intra-Pontide Suture probably represents trace of the Rheic Suture in Turkey, along which Avalonia and Armorica collided during Early Carboniferous.</p><p><strong>Key words:</strong> Intra-Pontide Suture, Istanbul Zone, Rheic Suture, detrital zircon, U-Pb ages, provenance, Hf isotopes</p>

Chapter 35: Gold Deposits of the Jiaodong Peninsula, Eastern China

2020 ◽  
pp. 753-774
Author(s):  
Kun-Feng Qiu ◽  
Richard J. Goldfarb ◽  
Jun Deng ◽  
Hao-Cheng Yu ◽  
Zong-Yang Gou ◽  
...  
Keyword(s):  
South China ◽  
North China ◽  
Gold Mineralization ◽  
Eastern China ◽  
Gold Deposits ◽  
Fault System ◽  
South China Block ◽  
North China Block ◽  
The North ◽  
Basement Rocks

Abstract The Jiaodong gold province, within the eastern margin of the North China block and the translated northeastern edge of the South China block, has a stated premining gold resource exceeding 4,500 metric tons (t). It is thus one of the world’s largest gold provinces, with a present cumulative annual production estimated at 60 t Au. More than 90% of the Jiaodong gold resource is hosted by batholiths and related bodies of the Linglong (ca. 160–145 Ma) and, to a lesser degree, Guojialing (ca. 130–122 Ma) suites. The intrusions were emplaced into high-grade metamorphic basement rocks of the Precambrian Jiaobei (North China block) and Sulu (South China block) terranes during a 70-m.y.-period of lithospheric delamination, extensional core complex formation, and exhumation. The deposits are located about 20 to 200 km to the east of the continental-scale NNE-striking Tancheng-Lujiang (Tan-Lu) strike-slip fault system. They occur along a series of more regional NNE- to NE-striking brittle and ductile-brittle faults, which appear to intersect the Tan-Lu main structure to the southwest. This system of early to middle Mesozoic regional thrust faults, reactivated during Cretaceous normal motion and ore formation, tends to occur along the margins of the main Linglong batholiths or between intrusions of the two suites of granitoids. Orebodies are mainly present as quartz-pyrite veins (Linglong-type) and as stockwork veinlets and disseminated mineralization (Jiaojia-type). The two mineralization styles are transitional and may be present within the same gold deposit. The ca. 120 Ma timing of gold mineralization correlates with major changes in plate kinematics in the Pacific Basin and the onset of seismicity along the Tan-Lu fault system, with the enormous fluid volumes and associated metal being derived from sediment devolatilization above the westerly subducting Izanagi slab.

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