Formation and evolution of Precambrian continental lithosphere in South China
TL;DR: In this paper, an overview of the formation and evolution of the Precambrian continental lithosphere in South China is presented based on an integrated study of zircon U-Pb ages and Lu-Hf isotopes in crustal rocks, with additional constraints from Re-Os isotope data on mantle derived rocks.
About: This article is published in Gondwana Research.The article was published on 2013-05-01. It has received 307 citations till now. The article focuses on the topics: Zircon & Archean.
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TL;DR: In this article, the authors proposed a model for the origin of the 2.55-2.50-Ga metamorphic pulse in the North China Craton (NCC), which is interpreted as a major phase of juvenile crustal growth in the craton.
1,181 citations
TL;DR: In the last three decades, extensive geological, geochemical and geophysical investigations have been carried out on these cratonic blocks and intervening orogenic belts, producing an abundant amount of new data and competing interpretations.
617 citations
TL;DR: The Jiangnan Orogen is considered as a continent-continent collisional belt resulting from the closure of a Meso-Neoproterozoic ocean separating the southeastern margin of the Yangtze Block from the northwestern boundary of the Cathaysia Block.
362 citations
TL;DR: In this article, the authors provide a comprehensive synthesis of the state-of-the-art information from deformation analysis, magmatism, geochronology, tomography and other fields from this region.
265 citations
TL;DR: In this article, a geodynamic framework of the South China Craton in the Early Paleozoic and Early Mesozoic has been modeled as developing through either oceanic convergence or intracontinental settings, based on an integrated structural, geochemical, zircon U-Pb and Hf isotopic and mica 40Ar/39Ar geochronologic study.
Abstract: The geodynamic framework of the South China Craton in the Early Paleozoic and Early Mesozoic has been modeled as developing through either oceanic convergence or intracontinental settings. On the basis of an integrated structural, geochemical, zircon U-Pb and Hf isotopic, and mica 40Ar/39Ar geochronologic study we establish that an intracontinental setting is currently the best fit for the available data. Our results suggest that widespread tectonomagmatic activity involving granite emplacement and mylonitic deformation occurred during two distinct stages: ~435–415 Ma and ~230–210 Ma. The coeval nature of emplacement of the plutons and their ductile deformation is corroborated by the subparallel orientation of the mylonitic foliation along the pluton margins, gneissose foliation in the middle part of pluton, the magmatic foliation within the plutons, and the schistosity in the surrounding metamorphosed country rocks. The 435–415 Ma granitoids exhibit peraluminous, high-K characteristics, and zircons show negative eHf(t) values (average −6.2, n = 66), and Paleoproterozoic two-stage model ages of circa 2.21–1.64 Ga (average 1.84 Ga). The data suggest that the Early Paleozoic plutons were derived from the partial melting of the Paleoproterozoic basement of the Cathaysia Block. The 230–210 Ma granites are potassic and have zircons with eHf(t) values of −2.8–−8.7 (average −5.4, n = 62), corresponding to TDM2 ages ranging from 2.0 to 1.44 Ga (average 1.64 Ga), suggesting that the Early Mesozoic partial melts in Cathaysia were also derived from basement. The geochemical distinction between the two phases of granites traces continental crustal evolution with time, with the Early Mesozoic crust enriched in potassium, silicon, and aluminum, but deficient in calcium, relative to the Paleozoic crust. Kinematical investigations provide evidence for an early-stage ductile deformation with a doubly vergent thrusting pattern dated at 433 ± 1 to 428 ± 1 Ma (40Ar/39Ar furnace step-heating pseudoplateau ages obtained on muscovite and biotite from mylonite and deformed granite) and a late-stage strike-slip movement with sinistral sense of ductile shearing at 232 ± 1 to 234 ± 1 Ma (40Ar/39Ar furnace step-heating pseudoplateau ages) along an E-W direction. The geological, geochemical, and isotopic signatures likely reflect far-field effects in response to continental assembly events at these times.
242 citations
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TL;DR: A survey of the dimensions and composition of the present continental crust is given in this paper, where it is concluded that at least 60% of the crust was emplaced by the late Archean (ca. 2.7 eons).
Abstract: A survey is given of the dimensions and composition of the present continental crust. The abundances of immobile elements in sedimentary rocks are used to establish upper crustal composition. The present upper crustal composition is attributed largely to intracrustal differentiation resulting in the production of granites senso lato. Underplating of the crust by ponded basaltic magmas is probably a major source of heat for intracrustal differentiation. The contrast between the present upper crustal composition and that of the Archean upper crust is emphasized. The nature of the lower crust is examined in the light of evidence from granulites and xenoliths of lower crustal origin. It appears that the protoliths of most granulite facies exposures are more representative of upper or middle crust and that the lower crust has a much more basic composition than the exposed upper crust. There is growing consensus that the crust grows episodically, and it is concluded that at least 60% of the crust was emplaced by the late Archean (ca. 2.7 eons, or 2.7 Ga). There appears to be a relationship between episodes of continental growth and differentiation and supercontinental cycles, probably dating back at least to the late Archean. However, such cycles do not explain the contrast in crustal compositions between Archean and post-Archean. Mechanisms for deriving the crust from the mantle are considered, including the role of present-day plate tectonics and subduction zones. It is concluded that a somewhat different tectonic regime operated in the Archean and was responsible for the growth of much of the continental crust. Archean tonalites and trond-hjemites may have resulted from slab melting and/or from melting of the Archean mantle wedge but at low pressures and high temperatures analogous to modern boninites. In contrast, most andesites and subduction-related rocks, now the main contributors to crustal growth, are derived ultimately from the mantle wedge above subduction zones. The cause of the contrast between the processes responsible for Archean and post-Archean crustal growth is attributed to faster subduction of younger, hotter oceanic crust in the Archean (ultimately due to higher heat flow) compared with subduction of older, cooler oceanic crust in more recent times. A brief survey of the causes of continental breakup reveals that neither plume nor lithospheric stretching is a totally satisfactory explanation. Speculations are presented about crustal development before 4000 m.y. ago. The terrestrial continental crust appears to be unique compared with crusts on other planets and satellites in the solar system, ultimately a consequence of the abundant free water on the Earth.
3,656 citations
TL;DR: This article proposed a flat-slab subduction model for Mesozoic South China based on both sensitive high-resolution ion microprobe (SHRIMP) U-Pb zircon data and a synthesis of existing structural, geochronological, and sedimentary facies results.
Abstract: We propose a flat-slab subduction model for Mesozoic South China based on both new sensitive high-resolution ion microprobe (SHRIMP) U-Pb zircon data and a synthesis of existing structural, geochronological, and sedimentary facies results. This model not only explains the development of a broad (∼1300-km-wide) intracontinental orogen that migrated from the coastal region into the continental interior between ca. 250 Ma and 190 Ma, but can also account for the puzzling chain of events that followed: the formation of a shallow-marine basin in the wake of the migrating foreland fold-and-thrust belt, and the development of one of the world's largest Basin and Range–style magmatic provinces after the orogeny. The South China record may serve as an example of the multiple effects of flat-slab subduction, including migrating orogenesis and foreland flexure, synorogenic sagging behind the active orogen, postdelamination lithospheric rebound, and the development of a Basin and Range–style broad magmatic province.
1,612 citations
TL;DR: The crustal growth and stabilization of the North China Craton (NCC) relate to three major geological events in the Precambrian: (1) a major phase of continental growth at ca. 2.9-2.7 Ga, (2) the amalgamation of micro-blocks and cratonization at 2.5-3.5 Ga, and (3) Paleoproterozoic rifting-subduction-accretion-collision tectonics and subsequent high-grade granulite facies metamorphism-granitoid mag
1,320 citations
TL;DR: The continental crust has an andesitic bulk composition, which cannot have been produced by the basaltic magmatism that dominates sites of present-day crustal growth as mentioned in this paper.
Abstract: The continental crust has an andesitic bulk composition, which cannot have been produced by the basaltic magmatism that dominates sites of present-day crustal growth—at both convergent margins and within plates. These observations suggest that there may have been a different mode of continental crust generation in Archaean times, and may point to delamination of the lower crust as an important recycling process.
1,189 citations
TL;DR: In this paper, single zircons from two Early Cambrian volcanic horizons have been analyzed using the SHRIMP ion microprobe, revealing the presence of both detrital or xenocrystic grains as well as areas within grains that have lost radiogenic Pb.
Abstract: Single zircons from two Early Cambrian volcanic horizons have been analysed using the SHRIMP ion microprobe. Full details of the analytical procedures and data reduction are given. Zircons from tuff within the Lie de Vin Formation, near Tiout, Morocco, show little spread in U-Pb age and have a mean value of 521 ± 7 Ma (2σ). Those from a bentonite within unit 5 of the Meishucun section near Kunming, southern China, show relatively dispersed U-Pb ages, revealing the presence of both detrital or xenocrystic grains as well as areas within grains that have lost radiogenic Pb. The main population has a mean age of 525 ± 7 Ma, but a mean 207 Pb/ 206 Pb age of 539 ± 34 Ma which is a maximum estimate for the bentonite age. These results conflict with previous Rb-Sr whole rock ages of c. 580 Ma for overlying Cambrian shales at Meishucun, and c. 570 Ma for Atdabanian shales from the E. Yangtse Gorges area.
1,029 citations