Exhumation of ultrahigh‐pressure continental crust in east central China: Late Triassic‐Early Jurassic tectonic unroofing

Hacker, Bradley R.; Ratschbacher, Lothar; Webb, Laura E.; McWilliams, Michael; Ireland, Trevor; Calvert, Andrew T.; Dong, Shuwen; Wenk, Hans‐Rudolf; Chateigner, Daniel

doi:10.1029/2000jb900039

Cited by 635 publications

(458 citation statements)

References 64 publications

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“…245 Ma (Early Triassic) date is considered the age of the HP event in agreement with available U/Pb and Sm/Nd ages on UHP rocks from the Dabieshan and Sulu areas (e.g. Mattauer et al, 1985;Chen et al, 1992;Ames et al, 1993;Eide et al, 1994;Hacker et al, 2000;Li et al, 1994 andJahn, 1999). These radiometric dates are consistent with stratigraphy, since south of the study area, Middle Triassic limestone is involved in the recumbent folding but Late Triassic sandstone is undeformed ( Liu et al, 2001).…”

Section: Chronological Constraintssupporting

confidence: 63%

“…In the Dabieshan area, recent work recognized a main deformation phase coeval with amphibolite facies metamorphism, characterized by NW-SE trending mineral and stretching lineation associated with top-to-the-NW shearing (e.g. Hacker et al, 1995;Hacker et al, 2000 andFaure et al, 1999). Similar structures and kinematics are observed in the Sulu area Faure et al, 2003a).…”

Section: Introductionmentioning

confidence: 48%

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Triassic polyphase deformation in the Feidong-Zhangbaling Massif (eastern China) and its place in the collision between the North China and South China blocks

Lin

Faure

Wang

et al. 2005

Journal of Asian Earth Sciences

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The Feidong-Zhangbaling Massif is located between the Dabieshan and Sulu areas along the Tan-Lu fault in eastern China. Five tectonic-metamorphic events are distinguished there. The earliest deformation (D1) corresponds to a southward compression that occurred during subduction of the South China Block below the North China Block. Top-to-the-south shearing is coeval with Late Permian-Early Triassic blueschist facies metamorphism, and possibly with the development of south-verging recumbent folds in the Neoproterozoic-Paleozoic sedimentary cover of the South China foreland. The main ductile deformation (D2) is an extensional one, characterized by top-to-the-north shearing, coeval with the early stage of exhumation of the high-pressure rocks. A top-to-the-NW ductile shearing, and microfolds overturned to the northwest, belong to a second deformational phase of exhumation (D3) which is distinct from the main event (D2). Previous 40 Ar-39 Ar mica dates ranging between 245 and 212 Ma suggest Late Permian-Early Triassic ages for the D1 to D3 events. The D4 event produced NE-SW trending folds in the sedimentary cover interpreted as gravity collapse structures. A Late Cretaceous brittle extensional event (D5) controls the opening and infill of continental half-grabens. In the study area, the Tan-Lu fault is a Cretaceous brittle normal fault. The lack of ductile deformation presented along the Tan-Lu fault suggests that it did not play a significant role in the exhumation of high-pressure metamorphic rocks.

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Section: Chronological Constraintssupporting

confidence: 63%

Section: Introductionmentioning

confidence: 48%

Triassic polyphase deformation in the Feidong-Zhangbaling Massif (eastern China) and its place in the collision between the North China and South China blocks

Lin

Faure

Wang

et al. 2005

Journal of Asian Earth Sciences

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“…However, except large metagabbro and metagranodiorite blocks, all the rocks have undergone strong ductile shear deformation and formed diverse mylonites or mylonitic rocks. Since zircon U-Pb age data obtained for the equivalent unit in the Hong'an orogen are concentrated in the Neoproterozoic, it is generally accepted that the tectonic mélange zone represents a crustal segment of the South China Block [5, [16][17][18]. Huang et al [19] obtained a muscovite 40 Ar/ 39 Ar age of 256±1 Ma in the ductile shear zone and interpreted it as the time of deformation.…”

Section: Diachroneity Of the Tongbai Hp Metamorphic Terranementioning

confidence: 99%

Diachroneity of continental subduction and exhumation: Constraints from the Permian-Triassic HP metamorphic terrane in the Tongbai orogen, central China

Liu

Jahn

2013

Chin. Sci. Bull.

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High-pressure (HP) metamorphic terrane in the Tongbai orogen comprises two HP slices (I and II) and a tectonic mélange zone in the northeast and a blueschist-greenschist zone in the southwest. HP slice I is represented by the northern and southern eclogite zones on the two sides of the Tongbaishan antiform. HP slice II is represented by retrograded eclogite-bearing metamorphic enclaves in Cretaceous gneissic granites in the Tongbai Complex. U-Pb, Lu-Hf, Rb-Sr and 40 Ar/ 39 Ar multichronometric data indicate that the peak metamorphism of HP slice I took place at ~255 Ma, whereas the metamorphic ages of HP slice II are as young as 232-220 Ma. By contrast, the tectonic mélange zone near the suture was metamorphosed at ~256 Ma. Such a diachroneity of different slices across the direction of the orogen in the Hong'an-Dabie-Sulu HP/UHP terrane is ubiquitous, and it can be interpreted by a syn-subduction detachment/exhumation model. Furthermore, the metamorphic age of HP slice I in the Tongbai orogen is older than that of the equivalent HP slice in the Hong'an orogen by ~15 Ma, suggesting that the diachroneity may have also existed along the direction of the orogen. A seesaw-type subduction/exhumation model is proposed to explain this age disparity and the subduction of the South China Block becomimg shallower towards the west. The processes and mechanism of exhumation of ultrahighpressure (UHP) metamorphic rocks to the Earth's surface from mantle depths exceeding ~100 km remain as one of the most difficult problems in earth science. It appears that a simple mechanism involving buoyancy and erosion is unable to explain the rapid exhumation required for the preservation of coesite. Much attention should be paid to the deepseated tectonic processes of continental slab. Based on the nature of structural contacts and existence of metamorphic gaps between different HP/UHP metamorphic units in the Dora Maira Massif of the western Alps, Chopin [1] andSchreyer [2] inferred that the end of the downgoing slab might have successively broken to several slices during its subduction along very low geothermal gradients (~7C/km). The earlier subducted slices could be uplifted as the overlying hanging-walls during the subduction of the later underlying slices. Liu and Hu [3] have formerly noticed the similarity of HP/UHP terrane from the Dabie Mountains and the Dora Maira Massif. Lately Liu et al. [4,5] distinguished UHP, HP and low-temperature (LT) HP slices and a tectonic mélange zone with the time difference of exhumation of ~30 Ma in the Hong'an orogen on the basis of thermobaric structure and geochronological data, and proposed a diachronous subduction/exhumation model for the formation of

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“…The orogen-scale structure of the axial Dabie structural belt is an antiform [53]. The north limb has north dipping foliation, north plunging lineation, and top-north shear sense formed as the footwall UHP-HP rocks were drawn southeastward out from beneath the low-grade hanging wall.…”

Section: Axial Dabie Structural Beltmentioning

confidence: 99%

“…The north limb has north dipping foliation, north plunging lineation, and top-north shear sense formed as the footwall UHP-HP rocks were drawn southeastward out from beneath the low-grade hanging wall. The south limb carries similar structures that have been rotated through horizontal to southward inclinations [53]. Based on the study in the western part of the Dabie orogen, Li et al [54] found that rocks of this orogen have been subjected to pervasive ductile deformation, and formed as asymmetric "antiform" around the core of the Xinxian UHP eclogite-facies zone.…”

Section: Axial Dabie Structural Beltmentioning

confidence: 99%

Mesozoic basin development and its indication of collisional orogeny in the Dabie orogen

Liu

Zhang

2012

Chin. Sci. Bull.

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The Dabie orogen underwent deep continental subduction, rapid exhumation, and the huge amount of erosion during the Mesozoic. Its tectonic evolution, especially how its evolution was recorded by sedimentary basins at the flanks of the Dabie orogen is one of the most important issues of the world's attention. These years, newly studies of basin sedimentology, combined with structural geology, have shown a fundamental progress. The overall distribution of different basin types in the orogen indicates that shortening and thrusting at the margins of the orogen from the Late Triassic to the Early Cretaceous controlled the foreland basins, and extension, doming and rifting were initiated in the core of the orogen from the Jurassic to the Early Cretaceous and were expanded to the whole orogen after the Late Cretaceous. Therefore, The Dabie orogen records gradual transition from overall shortening and thrusting to dominantly extension and rift basin formation expanded from its core to its margins, although these shortening and extension overlapped in time from the Jurassic through Early Cretaceous at crustal levels. The unroofing ages of the ultra-high pressure (UHP) metamorphic rocks in the Dabie orogen change from Early Jurassic to Late Jurassic westward. The depth of exhumation increases eastwards. The sediment sources for the Hefei basin are mostly composed of the deeply exhumed, axial Dabie metamorphic complex, and the sediment sources for the Middle Yangtze basin are mostly from cover strata in the southern orogen and related strata with subjacent (i.e. subsequently overthrusted) Mianlue suture belt. Geodynamic analysis represents that continental collision between the North China Block and the South China Block along the Shangdan and Mianlue sutures, subsequently northwestward progradation of the Jiangnan fold and thrust belt, and the underthrusting of the North China Block along the Northern Boundary Fault of Qinling Range led to crustal thickening, gravitational spreading and balanced rebound of the resultant thick crustal welt, and multi-episodic exhumation of the HP/UHP metamorphic rocks. The future studies by the methods of tracing the Dabie orogeny through deposition in the marginal basins should focus on eastward extension of the Mianlue suture, thrust and overlap of the Dabie HP/UHP metamorphic block on different lithotectonic zones and basins along the northern South China Block, the structural framework of the source area of the basins in the syn-depositional stage, the basin lateral extension, huge amount of erosion and sediment transportation from the Dabie blanket and basement rocks, and recovery of subducted and removed structural units within the Dabie orogen, etc.Dabie orogen, sedimentary basin, evolution of basin/mountain system, HP/UHP metamorphic rocks, provenance analysis, exhumation process, depositional paleogeography

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Exhumation of ultrahigh‐pressure continental crust in east central China: Late Triassic‐Early Jurassic tectonic unroofing

Cited by 635 publications

References 64 publications

Triassic polyphase deformation in the Feidong-Zhangbaling Massif (eastern China) and its place in the collision between the North China and South China blocks

Triassic polyphase deformation in the Feidong-Zhangbaling Massif (eastern China) and its place in the collision between the North China and South China blocks

Diachroneity of continental subduction and exhumation: Constraints from the Permian-Triassic HP metamorphic terrane in the Tongbai orogen, central China

Mesozoic basin development and its indication of collisional orogeny in the Dabie orogen

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