Qinling-Dabie Orogen Research Articles

Detrital zircon provenance of the Late Triassic Songpan-Ganzi complex: Sedimentary record of collision of the North and South China blocks

Research Article| February 01, 2006 Detrital zircon provenance of the Late Triassic Songpan-Ganzi complex: Sedimentary record of collision of the North and South China blocks Amy L. Weislogel; Amy L. Weislogel 1Department of Geological and Environmental Sciences, Stanford University, Stanford, California 94305, USA Search for other works by this author on: GSW Google Scholar Stephan A. Graham; Stephan A. Graham 1Department of Geological and Environmental Sciences, Stanford University, Stanford, California 94305, USA Search for other works by this author on: GSW Google Scholar Edmund Z. Chang; Edmund Z. Chang 1Department of Geological and Environmental Sciences, Stanford University, Stanford, California 94305, USA Search for other works by this author on: GSW Google Scholar Joeseph L. Wooden; Joeseph L. Wooden 2U.S. Geological Survey, 345 Middlefield Road, Menlo Park, California 94025, USA Search for other works by this author on: GSW Google Scholar George E. Gehrels; George E. Gehrels 3Department of Geosciences, University of Arizona, Tucson, Arizona 85721, USA Search for other works by this author on: GSW Google Scholar Hengshu Yang Hengshu Yang 4Sichuan Bureau of Geology and Ore Examination, Mianyang, Sichuan 621000, People's Republic of China Search for other works by this author on: GSW Google Scholar Geology (2006) 34 (2): 97–100. https://doi.org/10.1130/G21929.1 Article history received: 08 Jun 2005 rev-recd: 07 Oct 2005 accepted: 12 Oct 2005 first online: 09 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share MailTo Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation Amy L. Weislogel, Stephan A. Graham, Edmund Z. Chang, Joeseph L. Wooden, George E. Gehrels, Hengshu Yang; Detrital zircon provenance of the Late Triassic Songpan-Ganzi complex: Sedimentary record of collision of the North and South China blocks. Geology 2006;; 34 (2): 97–100. doi: https://doi.org/10.1130/G21929.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract Using detrital zircon geochronology, turbidite deposystems fed from distinct sediment sources can be distinguished within the Songpan-Ganzi complex, a collapsed Middle to Late Triassic turbidite basin of central China. A southern Songpan-Ganzi deposystem initially was sourced solely by erosion of the Qinling-Dabie orogen during early Late Triassic time, then by Qinling-Dabie orogen, North China block, and South China block sources during middle to late Late Triassic time. A northern Songpan-Ganzi system was sourced by erosion of the Qinling-Dabie orogen and the North China block throughout its deposition. These separate deposystems were later tectonically amalgamated to form one complex and then uplifted as the eastern Tibet Plateau. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Provenance of Carboniferous sedimentary rocks in the northern margin of Dabie Mountains, central China and the tectonic significance: constraints from trace elements, mineral chemistry and SHRIMP dating of zircons

A suite of slightly metamorphosed Carboniferous sedimentary strata occurs in the northern margin of the Dabie Mountains, central China. It consists, in ascending order, of the upper Huayuanqiang Formation (C 1), the Yangshan Formation (C 1), the Daorenchong Formation (C 1–2), the most widely distributed Huyoufang Formation (C 2) and the Yangxiaozhuang Formation (C 2). The provenance of the Carboniferous sedimentary rocks is constrained by the integration of trace elements, detrital mineral chemistry and sensitive high resolution ion microprobe (SHRIMP) dating of detrital zircons, which can help to understand the connection between the provenance and the Paleozoic tectonic evolution of the Qinling–Dabie Orogen. The trace element compositions indicate that the source terrain was probably a continental island arc. Detrital tourmalines were mainly derived from aluminous and Al-poor metapelites and metapsammites, and some are sourced from Li-poor granitoids, pegmatites and aplites. Detrital garnets, found only in the uppermost Huyoufang Formation, are almandine and Mn-almandine garnets, indicating probable sources mainly from garnetiferous schists, and partly from granitoid rocks. The detrital white K-micas are muscovitic in the Huayuanqiang, Daorenchong and Huyoufang Formations, and phengitic with Si contents (p.f.u.) from 3.20 up to max. 3.47–3.53 in the uppermost Huyoufang and the Yangxiaozhuang Formations, a meta-sedimentary source. Major components in the detrital zircon age structure for the Huyoufang Formation range from 506 to 363 Ma, centering on ∼400 and ∼480 Ma, which is characteristic of the Qinling and Erlangping Groups in the Qinling and Tongbai Mountains, central China. Evidently, the major source of the Carboniferous sedimentary rocks in the northern margin of Dabie Mountains was from the southern margin of the Sino-Korean Craton represented by the Qinling and Erlangping Groups. The source area was an island-arc system during the Early Paleozoic that collided with the Sino-Korea plate towards the end of the Early Paleozoic or during the Devonian. A prominent feature in the detrital zircon age structure of the Huyoufang Formation is the Neoproterozoic detritus, which could be derived only from the Yangtze Craton. Reasonable interpretation of the two distinct source materials for the Huyoufang Formation is that the two plates were juxtaposed through collision before the late Carboniferous.

Subduction, collision and exhumation in the ultrahigh-pressure Qinling-Dabie orogen

Abstract High-pressure metamorphism and ophiolite emplacement (Songshugou ophiolite) attended suturing of the Yangtze craton to Rodinia during the c. 1.0 Ga Grenvillian orogeny. The Qinling microcontinent then rifted from the Yangtze craton at c. 750 Ma. The Erlangping intraoceanic arc formed in the Early Ordovician, was emplaced onto the Qinling microcontinent in the Ordovician-Silurian, and then both units were accreted to the Sino-Korea craton before being stitched together by the c. 400 Ma Andean-style Qinling arc. Subsequent subduction beneath the Qinling-Sino-Korean plate created a Devonian-Triassic accretionary wedge that includes eclogites, and formed a coeval volcano-plutonic arc that stretches from the Longmen Shan to Korea. In the Late Permian-Early Triassic, the northern edge of the South China Block was subducted to >150 km depth, creating the diamond- and coesite-bearing eclogites of the Dabie and Sulu areas. Exhumation from the mantle by lithosphere-scale extension occurred between 245 and 195 Ma during clockwise rotation of the craton. The Yangtze-Sino-Korea suture locally lies tens of km north of the exhumed UHP-HP part of the South China Block, implying perhaps that the very tip of the South China Block was not subducted, or that the UHP-HP rocks rose as a wedge that peeled the upper crust of the unsubducted South China Block from the lower crust. The Tan-Lu fault is an Early Cretaceous to Cenozoic feature. The apparent offset of the Dabie and Sulu UHP terranes by the Tan-Lu fault is a result of this Cretaceous to Cenozoic faulting combined with post-collisional extension north of Dabie.

The development of spiral-shaped inclusion trails during multiple metamorphism and folding

Three periods of mineral growth and three generations of spiral-shaped inclusion trails have been distinguished within folded rocks of the Qinling-Dabie Orogen, China, using the development of three successive and differently trending sets of foliation intersection axes preserved in porphyroblasts (FIAs). This progression is revealed by the consistent relative sequence of changes in FIA trends from the core to rim of garnet porphyroblasts in samples with multiple FIAs. The first and second formed sets of FIAs trend oblique to the axial planes of macroscopic folds that dominate the outcrop pattern in this region. The porphyroblasts containing these FIAs grew prior to the development of the macroscopic folds, yet the FIAs do not change orientation across the fold hinges. The youngest formed FIAs (set 3) lie subparallel to the axial planes of these folds and the porphyroblasts containing these FIAs formed in part as the folds developed. The deformation associated with all three generations of spiral-shaped inclusion trails in garnet porphyroblasts involved the formation of subhorizontal and subvertical foliations against porphyroblast rims accompanied by periods of garnet growth; pervasive structures have not necessarily formed in the matrix away from the porphyroblasts. The macroscopic folds are heterogeneously strained from limb to limb, doubly plunging and have moderately dipping axial planes. The consistent orientation of Set 1 FIAs indicates that the development of spiral-shaped inclusion trails in porphyroblasts with FIAs belonging to Set 2 did not involve rotation of the previously formed porphyroblasts. The consistent orientation of Sets 1 and 2 FIAs indicate that the development of spiral-shaped inclusion trails in porphyroblasts with FIAs belonging to Set 3 did not involve rotation of the previously formed porphyroblasts during folding. This requires a fold mechanism of progressive bulk inhomogeneous shortening and demonstrates that spiral-shaped inclusion trails can form outside of shear zones.

Compression to extension switch during the Middle Triassic orogeny of Eastern China: the case study of the Jiulingshan massif in the southern foreland of the Dabieshan

The Jiulingshan massif is an E–W trending anticlinorium in the South China Block (SCB) that forms the southern foreland of the Qinling–Dabie orogen. The Jiulingshan consists of Middle Proterozoic (ca. 1 Ga–800 Ma) metamorphic and plutonic rocks unconformably overlain by Sinian to Triassic rocks. In these cover rocks, two episodes of deformation of pre-Late Triassic age are recognized. Namely, a N–S compressional phase characterized by south verging thrusts, upright folds and vertical cleavage followed by an extensional phase characterized by layer parallel slip, collapse folds and extensional allochthons of Proterozoic slate on top of Carboniferous to Middle Triassic carbonates. The extensional tectonics appears to be a mechanical consequence of the compressional tectonics. On a regional scale, the Jiulingshan massif forms one of the domed crustal scale shear zones of the SCB that accommodated the continuing convergence that immediately followed the Qinling–Dabie collision.

U/Pb zircon ages constrain the architecture of the ultrahigh-pressure Qinling–Dabie Orogen, China

New SHRIMP and TIMS zircon ages, 40Ar/ 39Ar ages, and eclogite locations contribute significantly to our understanding of the ultrahigh-pressure Dabie Shan. (1) The geographic extent of the Yangtze craton that was subducted to ultrahigh pressure extends to the northern edge of the Dabie Shan. (2) The northern half of the Dabie Shan is a magmatic complex, intruded over a 10-Myr interval between 137 and 126 Ma, that accommodated ∼100% N–S stretching of the pre-existing collisional architecture. (3) Granitic orthogneisses and enclosing ultrahigh-pressure paragneisses have indistinguishable zircon populations. The population of Triassic zircon ages ranges from ∼219 to ∼245 Ma, leading us to question the prevailing assumption that 219 Ma zircons formed at ultrahigh pressure, and to propose instead that they reflect late retrogression at crustal pressures following the bulk of exhumation.

Geochronological Evidence for the In situ Tectonic Relationship in the Dabie UHP Metamorphic Terrane, Central China

The Dabie Mountains and the Su-Lu region in central China are known to contain the largest distribution of ultrahigh pressure metamorphic (UHPM) rocks in the world. They are parts of the Qinling-Dabie orogen formed by collision between the Sino-Korean and Yangtse cratons. The preservation of UHP minerals has inspired different models to explain the deep subduction of continental crust and the mechanisms for subsequent unroofing of the UHPM rocks. In the absence of good constraints from geochemical, isotopic and age data for different lithotectonic units, numerous tectonic models have been proposed. It appears that the greatest controversy to date concerns the primary age and the nature of eclogite protoliths, their tectonic relation with the associated ultramafic rocks and enclosing granitic gneisses ('in situ' vs 'foreign' hypothesis), the areal extent of the UHPM rocks, and their mode of exhumation. Here we report new geochemical and Sr-Nd for the host gneisses of the largest coesite-bearing eclogite body in this terranne the Bixiling Complex. These data will be used to tackle the problem of eclogitegneiss tectonic relationship. The Bixiling Complex has well preserved its UHP paragenesis of which coesite and quartz pseudomorph occur as inclusions within garnet or omphacite. In contrast, the host gneisses exhibit a typical phase assemblage of the albite-epidote amphibolite facies (plagioclase + biotite + zoisite + K-feldspar + quartz + muscovite + apatite) corresponding to the retrograde metamorphism of the Bixiling Complex. However, the presence of garnet, though very minor in amount, may suggest a previous higher metamorphic condition. The country rocks are paragneisses or orthogneisses of TTG composition (tonalite-trondhjemite-granodiorite). They are all characterized by negative Ti, P, Ta and Nb anomalies in their spidergrams, hence suggesting their protolith formation in ancient arc environments. Much of the protoliths of the gneisses from the Dabie UHP terrane was probably formed in late Proterozoic (750-800 Ma; Ames et al., 1996; Rowley et al., 1997; Hacker et al., 1998). However, there is indication of older protoliths from Sm-Nd model age (TDM) data for gneisses from Shuanhe (Chen and Jahn, 1998). The Bixiling gneisses have TDM of 1.3 to 1.5 Ga, and and(800 Ma) = +4.2 _+ 0.4, indicating their late Proterozoic formation and juvenile character. Geochronological constraints are obviously essential for understanding the gneiss-eclogite tectonic relationship. Rb-Sr isotope analyses of whole-rock and constituent phases for five gneisses yielded a tight range of Ms-WR-Zo isochron ages from 194 to 198 Ma, and Bt-Zo isochron ages from 170 to 184 Ma (Fig. l and 2). On face values, the Ms Rb-Sr ages are only slightly younger than the Phg-WR Rb-Sr ages obtained on the coesite-bearing eclogite from the Bixling Complex (Fig. 3; 198 to 223 Ma; Chavagnac and Jahn, 1996). Moreover, the Bt RbSr ages are also in agreement with that of an amphibolite near the Bixiling Complex. Thus, when combined the new age information with the published zircon age data (Ames et al., 1996;

Petrology, Metamorphic Process and Genesis of The Dabie—Sulu Eclogite Belt, Eastern—Central China

Abstract The Qinling—Dabie—Sulu high—pressure and ultra—high pressure metamorphic belt was formed by subduction and collision between the North China and Yangtze plates. The study of the eclogite belt is very important in understanding the evolution of the Qinling Dabie orogen. In the present paper the geology, petrology, minerology and chronology of the eclogites in the Dabie and Sulu areas are described. The principal conclusions of this work are as follows: (1) Based upon the field occurrence and the P—T conditions of the eclogites, two types of eclogite can be distinguished: Type 1—the low‐temperature and high—pressure eclogite in the mid‐late Proterozoic metamorphic series, and Type 2—the ultra‐high pressure eclogite in the late Archaean to early Proterozoic metamorphic complex. In the Dabie area, the ultra‐high‐pressure eclogite, high—pressure eclogite and epidote‐blueschist units are nearly parallel to each other and stretch intermittently from north to south. (2) The P—T conditions of the high—pressure eclogites and ultra‐high pressure eclogites have been estimated. The former are formed at 450—550°C and 1.4‐1.6 GPa; while the latter at 650—870°C and >2.7—2.9 GPa in the Dabie area and at 820—1000°C and > 2.8—3.1 GPa in the Sulu area. The metamorphic temperatures of the eclogites increase progressively from west to east. (3) The ultra—high pressure eclogites were subjected to 5 stages of metamorphism: pre‐eclogite epidote amphibolite facies, peak coesite eclogite facies, post—eclogite amphibolite facies, epidote—blueschist facies or epidote amphibolite facies and greenschist facies. The general features of the PTt path of the ultra‐high pressure eclogite are: clockwise pattern, progressive metamorphism being a process of slow increasing temperature and rapid increasing pressure, and the retrogressive section with nearly isothermal decompression at the early stage, isobaric cooling at the middle stage and nearly isothermal decompression at the late stage. (4) At least two stages of high‐pressure metamorphism occurred in the orogenic belt: the high‐pressure eclogite and ultra‐high pressure eclogite were formed by the subduction of the oceanic crust northward beneath the North China plate or the Dabie block during the Caledonian; while the epidote‐blueschist belt came into being by subdution and collision between the two continental plates during the Indosinian. (5) Due to the continuous sequential subduction of the cold plate, the ultra high—presssure metamorphic rocks were uplifted to the crust by the underplating processes. They can be preserved just because of the “frozen effect” resulting from the continuous subduction of the cold plate. (6) The carbonates, such as magnesite, breunnerite, aragonite and dolomite, and the H2O—bearing minerals, such as phengite, epidote and zoisite, were stable during the high‐pressure and / or ultra—high pressure metamorphism.