Subduction, collision and exhumation in the ultrahigh-pressure Qinling - Dabie orogen BRADLEYR. HACKERI, LOTHAR RATSCHBACHER2& J. G. LIOU3 IGeological Sciences,University of California, SantaBarbara, CA 93106, USA 2lnstitutfiir Geologie,Technische Universitiit BergakademieFreiberg, Freiberg, D-09599, Germany 3Geologicaland EnvironmentalSciences, Stanford University, Stanford,CA 94305, USA c':. Abstract: High-pressure metamorphism and ophiolite emplacement (Songshugou ophio- lite) attendedsuturing of the Yangtze craton to Rodinia during the c.l.O Ga Grenvillian oro- . geny. The Qinling microcontinent then rifted from the Yangtze craton at c.750Ma. The .;~, microcontinentErlangping intraoceanic in the Ordovician-Silurian, arc formed in the Early and Ordovician, then both units was wereemplaced accreted onto tothe the Qinling 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 stretchesfrom the Longmen Shan to Korea. In the Late Permian-Early Triassic, the northern edge of the South China Block was subductedto > 150 km depth, creating the diamond- and coesite-bearing eclogites of the Dabie and Sulu areas. Exhumation from the mantle by lithosphere-scaleextension occurred between 245 and 195 Ma during clock- wise 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 perhapsthat the very tip of the South China Block was not subducted,or that the UHP-HP rocks rose as a wedge that peeledthe upper crust of the unsubductedSouth China Block from the lower crust. The Tan- Lu fault is an Early Cretaceousto Cenozoic feature. The apparent offset of the Dabie and Sulu UHP terranes by the Tan-Lu fault is a result of this Cretaceousto Cenozoic faulting combined with post-collisional extension north of Dabie. The Sino-Korean craton and the Qinling micro- basementoutcrops can be assignedeither a Sino- 3. continent colli~ed in the Ordovician-Silurian. Kore;an or Yangtze crat.on affini~y, where~s the ~,., The North China Block (NCB) and the South affinIty of areally extensIvedomaIns of sedImen- ~ China Block (SCB) collided in the Permo-Triassic. tary strata or of volcano-plutonic complexes can 1,4 The orogenic belt associatedwith thesecollisions be ambiguous. 'North China Block' and 'South "f);' and intervening tectonism extends c.2000km China Block' are used to refer to the continental west-east through the Qinling, Tongbai, Dabie blocks north and south of the Qinling-Dabie- Shan and Sulu areasand into Korea (Fig. 1). It is Sulu suture. of specialinterest because it containshigh-pressure The Sino- Korean craton is subdivided into (HP) rocks of four different ages: Grenvillian, three units: the western, eastern and central Devonian, Carboniferousand Triassic. This paper blocks. The western and eastern blocks are aims to provide a review of the collision zone as Archean cratons linked by a central suture belt both a summary of what conclusions have been that formed during collision at c.1.8 Ga (Zhao drawn where and with which data, and as a guide et at. 2000). The U-Pb zircon ages from the to future reseal\;h. Sino-Korean craton cluster at c.3.8, 3.3, 3.0, 2.5 and 1.7-1.8Ga (Song et at. 1996; Yu et at. 1996; Zhao et at. 2000). The craton consists of Smo-Korean craton a basement of Archaean to Proterozoic meta- In our usage, the Sino-Korean and Yangtze cra- morphic rock overlain by a relatively uninter- tons comprise Precambrian basement and cover rupted 4-8 km thick superjacent section of as describedbelow; in principle, all Precambrian Sinian (Late Proterozoic to Early Cambrian) to From: MALPAS, J., FLETCHER,C. J. N., ALl, J. R. & AITCHISON, J. C. (eds) 2004. Aspects of the Tectonic Evolution of Chiua. Geological Society, London, Special Publications, 226, 157-175. 0305-8719/04/$15 ((;) The Geological Society of London 2004. 1 ! ! i i , . K22025 m2029 26 26 Geochronology Explanation Foziling 9 Z667,739 M242 zircon core (if present) m225 unit names are italicized b204, 2239 H742,77026 coesite eclogite 2 location reference Explanation Z391 M21825 26 (Hu et al.,1995) K205[c. 870]* K180 post-Triassic rocks m2139 Z75729 age (Ma) Sm23136 Sm2448 Z87025 K: 40Ar/39Ar K-feldspar Sm21048 40 39 Triassic sedimentary rocks 36 5 B: Ar/ Ar biotite Sm228 z480 M: 40Ar/39Ar K-white mica Sm23842 11 40 39 46 Rbwr402 Ar4218 H: Ar/ Ar hornblende Sino-Korean craton cover and basement; letter shows age of youngest rocks Z229[707] Sm20848 2 b: K/Ar biotite 4 KAr394 26 38 Rb486 m: K/Ar K-white mica contact, depositional or intrusive H280 2 Sm400 3 9 h: K/Ar hornblende Cretaceous plutons KAr402 8 m354 Rbwr452 2 o inferred contact 27 Rb383 2 KAr380 113 Z: U/Pb zircon M185,H214 Rb6704 2 KAr403 9 9 35o m4203 KAr3702 KAr401 2 Rbwr424 Rbwr991 Rm: Rb/Sr whole-rock-K-white mica fault Sm218-210 x6, 4 20 KAr480 Triassic plutons Northern Z76825 30 Rb444 Z437 Rbwr7949 Rb: Rb/Sr whole-rock-biotite thrust fault Rm 223-198 9 ) 3 Rbwr973 Orthogneiss Rbb194,194,197,198,198 47 B m425 45 3 Sm983 antiform M205,206,206,212 b432 C Paleozoic plutons H~400K220 45 Z1.329 Z2.129 35 5 N synform B201,202,211,210 45 H420 ( K230 z488,487 n homocline 22 o Kuanping unit Z214 Sm246, t 26 23 24 29 Songshugou a Z739 Rb240 H225 Z218 r structural trend 41 c Erlanping unit Z223[1.8] n 26 M179 23 24 a coesite eclogite Rm236 M190 K176, 45 14 Dengfeng e H³386K270 Pb2.5 r 25 M183,19026Z238[1.9] o Z798 Dengfeng Qinling unit quartz eclogite mz223,20934Z233[2.5] K northern Liuling T3 - 35 greenstone o Sm231 Sm226x2, 22 31 2 n → 22 37 =Qinling(?) Rb2.8 i Songshugou ophiolite eclogite amphibolite Z218 Z638 772 Rbb169,171,173,174,181 S 24 B227 Z218-240,K203, ) 22 25 2 → Z674 Z781 o B B199,216, 111 UPb2.4 Liuling unit blueschist greenschist 24 2 C M195,H195(?) Sha Rb2.6 S coesite Lu n f ( o ault eclogite 31 36 22 35 n Douling, Sujiahe (incl. Huwan), Luzhenguang unit Z78126 Z772 Sm221 Z227,B190 o 24 26 t 25 M200B190 ,B195,K195 a Z224 9 29 r b182,216,231 Z218 c o Triassic high-pressure and ultrahigh-pressure rocks 115 28 34 e Z230,mz209 M191 7 z o M178 P2 t 33 g Yangtze craton cover and basement; 24 n M196 K204 Songxian a tz eclogite 14 letter shows age of youngest rocks quar 2.8 Y Taihua gneiss Lu Shan M20624 M1951 2 2 KAr127 2 26 KAr100 Z2.6 M210,198 B~197,M20826M2161 K100-105 M22124 m2109 2 2 Z1.5 2 Xiong'er KAr370 KAr103 3 2 49 b430 K55 KAr141 Foziling sed: Pb 2.5, 1.9-1.8 Ga, 1.0-0.7 Ga, 455 Ma Kuanping 49 Lushi 2 Queshan Foziling granites: Z719-766 3 T KAr1402 KAr131 49 b121 b3893 Z3912 3 Meishan Fm. Luzh sed: Pb734-1.9 O 8 Rb105 45 b1243 Guandaokou H402K~200 Xiong'er KAr3842 2 Ar4218 Z2.0 C . T3J1 7 Lo-Nan F 45 Erlangping H434 B101 KAr3982 3 m2159 b135 45 G 7 Luzhenguang N 9 K95 Srwr991 H433 Kua 9 Foziling 3 nping m450,433 b341 I F. 26 H<498 K100, 60 Songshugou Qinling z0.8,2.613 KAr4072 n fau 3 1 L Shang-Dan → 45 HT4047 ita lt b140 B327 M348 K~1000 220 KAr4852 oz 8 13 O Xinyang M Sm224 1 2 Xinyang z470, 435 → 17 e m186, 2289 n- 25 B314 8 KAr795 N M220 256 r zon 9 tia Z771 4 Shangnan KAr718 4 ea m196,203 o Xi'an Rb143 N M301,247 5 2 16 Xinyang sh ia Z725 13 n X Danfeng → 45 z762 Z747 Douling z1.7Sm1.9Sr422H833 12 G H401 wa ous Northern Rb40210 45 B297,264 K~1000 250 z746, 776 7 7 Hu ace t t H152 or K? K205±5 45 2 BH316 H135 33 re Orthogneiss 45 H~1000 KAr880 Suixian & M205 Z404,780,1.0,1.5 13 C ul 4 45 M243,266 a Liuling M806->750 Yaolinghe A f I Ar214 H400→222M22713 coesite 3 e 2 I D A B I E b135 Lu Heih Z656 eclogite Ar2174 rieb2161 B12013 n- 1 Shanyang M232 Wudang & Ta F. Yaolinghe H O N G 'A N he F.Q Nanyang en u Z226,85422 44 Ch go Basin Z~750 a g F. M18028 Sh Shan-Fen Z22732 coesite Rb4184 Z77826 eclogite Z2004 Xiaomoling K17133 25 Z761 quartz eclogite Shiyan blueschist P2 M235,K20526 M225, 22218 H23745 S H A N lu F. M232→15045 Gong T S 33 Wudang Shan zone M234 J hear 3 J n s amphibolite 1 Huwa Z660,73526 17 Sm44643 M230 coesite M19017 M~400x217Z312[~400]21 M23323 Z74515 2 21 F. Z307 Z311,307[433] M26317 mT2079 ang 39 40 1 Wuhan P Fangxia Z400H399? Sm422 m201,2059 blueschist Wud 21 Z232 M196,22233 33 J2 o M22433 M231 M19518 eclogite 108 o 33 J1 T 18 qua 313 M230 rtz J3 M212 M2473324917 eclogite Z77926 M23617 M23433 M20533 33 eclo M207 Zhuqi F. gite b2269 m2329 M21417 N Shennong →am M20118M19833 ph ~2.9, 2.9-3.3 (19) iboli 0.9(15) te m1979 M19533 32¡ 33 0.9(15) Huangling M19633 M237 K16933 J 109¡ M21318 2 31¡ J2 100 km 111¡ 30o 113o North South North China Block South China Block Sino-Korean craton Kuanping: Sino-Korean Erlangping- Qinling: Sino-Korean Northern Liuling: Southern Liuling: Douling: Yangtze Yangtze craton (southern margin) Pr oterozoic-Silurian Danfeng-Heihe cover, ophiolite and = Qinling(?) Paleozoic basement (northern margin) passive margin/ intraoceanic Yangtze basement flysch and molasse(?) +crustal derived accretionary wedge(?) arc Mesozoic evolution same Mesozoic Jurassic volcanics as Sino-Korean craton thru Early continental amalgamated by 400 Ma Upper Triassic Triassic Devonian- clastics continental Permian(?) marble, lacustrine to alluvial amphibolite, siliclastic & orthogneiss, Lower- paragneiss, marble, gneiss volcaniclastic acid to Middle Triassic Permian shallow marine-lacustrine amphibolite ~400Ma rocks dominantly evaporite, unstable shelf thru middle Carboniferous- Ti-rich carbonate & Devonian =Kuanping(?) contact angtze riftingangtze Y pillow basalt Early Permian andesites