The Distribution, P-T-t Evolution and Formation Mechanism of HP-UHP Metamorphic Rocks in the North Qinling Orogenic Belt
-
摘要: 北秦岭构造带早古生代的构造格局和演化过程一直是地学界比较关注也是存在较大争议的问题之一.在已有研究基础上，系统总结了本课题组近年来在北秦岭早古生代高压-超高压变质作用研究方面的进展，从变质作用角度对北秦岭早古生代的构造演化提供重要限定.丹凤斜长角闪岩中柯石英的发现为区内超高压变质作用的存在提供了最直接的矿物学证据；东秦岭秦岭杂岩中的斜长角闪岩普遍经历了高压-超高压榴辉岩相变质，具面状分布的特征，是陆壳俯冲/深俯冲作用的产物；高压-超高压榴辉岩和围岩片麻岩都记录了顺时针的P-T-t轨迹，峰期变质时代为500~490 Ma，之后主体又经历约470~450 Ma和约420~400 Ma两期抬升退变质叠加和部分熔融作用；高压-超高压岩石两期退变质和部分熔融发生的时代与北秦岭460~440Ma和~420Ma的两期岩浆事件的时代一致，说明北秦岭早古生代岩浆作用是深俯冲陆壳板片断离和碰撞造山结束后地壳伸展作用的岩浆响应；高压-超高压榴辉岩原岩形成时代约800 Ma，具有与南秦岭新元古代中晚期岩浆岩一致的地球化学特征，北秦岭超高压岩石的形成可能是商丹洋关闭后洋壳拖曳着南秦岭陆壳物质向北发生大陆深俯冲的结果，商丹洋在500 Ma主体应该已经关闭；秦岭岩群是部分而不是整体经历了大陆的深俯冲，现今的秦岭岩群是一个俯冲碰撞杂岩带而不是一个岩石地层单元或微陆块；北秦岭早古生代造山作用在中泥盆世已经结束，整体处于构造隆升后的剥蚀阶段，是南秦岭刘岭群碎屑岩的主要蚀源区，刘岭群沉积盆地形成于碰撞造山后的伸展构造背景而非弧前环境.Abstract: The Early Paleozoic tectonic framework and evolution history of the North Qinling orogenic belt (NQOB) is in great dispute and has drawn wide concern. In this contribution,we systematically summarized our recent progresses on Early Paleozoic HP-UHP metamorphism in the NQOB and constrained the Early Paleozoic tectonic evolution of the NQOB from the perspectives of metamorphism. The discovery of coesite in the Danfeng amphibolite provides a conclusive evidence for the UHP metamorphism in the NQOB. The amphibolites,which are widely distributed in Qinling Complex in East Qinling,commonly experienced HP-UHP metamorphism and are products of continental (deep) subduction. HP-UHP eclogites and host gneisses have clockwise P-T-t paths and similar peak metamorphic ages of 500-490 Ma,and experienced two stages retrogression and anataxis at 470-450 Ma and 420-400 Ma,respectively. The times of the two stage retrogression and anataxis are coincident with the magmatism in the NQOB,which occurred at 460-450 Ma and~420 Ma,suggesting that the Early Paleozoic magmatism in the NQOB were formed under the tectonic setting of breaking-off of deeply subducted continental slab and post-orogenic extension-thinning,respectively. The HP-UHP rocks have protolith ages of ca. 800 Ma,and geochemical characteristics similar to Mid-Late Neoproterozoic magmatic rocks from South Qinling,indicating that continental materials from South Qinling were dragged down to mantle depth and experienced UHP metamorphism by the north dipping Shangdan oceanic lithosphere,and the Shangdan Ocean was already closed at 500 Ma. The Qinling Group is a tectonic complex rather than a uniform stratigraphic unit or a microcontinent and only part of it underwent continental deep subduction. The Early Paleozoic orogenisis in North Qinling was ended and the HP-UHP rocks were exhumated up to the surface in Mid-Devonian,and became the main provenance of sedimentary rocks in Liuling group in South Qinling. The Liuling basin is a post-orogenic extensional basin,rather than a fore-arc basin.
-
图 2 丹凤斜长角闪岩锆石中的包裹体及其激光拉曼谱图
Coe.柯石英；Omp.绿辉石；Grt.石榴子石；Rt.金红石；Zrn.锆石.据宫相宽等(2016)
Fig. 2. Representative photographs and Raman spectra of mineral inclusions in zircons from Danfeng amphibolite
图 3 松树沟退变榴辉岩石榴石和锆石中绿辉石包裹体及基质中残留的绿辉石
Amp.角闪石；Zrn.锆石；Pl.斜长石；Ttn.榍石；Ilm.钛铁矿；Ep.绿帘石；Cpx.单斜辉石；Omp.绿辉石；Ap.磷灰石.据陈丹玲等(2015)
Fig. 3. The omphacite inclusions in garnet and zircon and relic omphacite in matrix of Songshugou retrograde eclogite
图 4 北秦岭高压-超高压变质榴辉岩及围岩片麻岩的年龄统计结果
数据引自Liu et al.(2016)；宫相宽(2017)；廖小莹(2018)及其参考文献
Fig. 4. Summary of ages for HP-UHP eclogites and host gneisses in the NQOB
图 6 北秦岭高压-超高压榴辉岩的地球化学特征
Fig. 6. The geochemical characteristics of HP-UHP eclogites in the NQOB
图 7 北秦岭古生代高压-超高压变质岩(a)、花岗岩(b)和刘岭群碎屑锆石(c)的年龄统计结果
花岗岩数据张成立等(2013)；变质岩和碎屑岩数据来自Liao et al.(2017)、宫相宽(2017)和廖小莹(2018)
Fig. 7. Summary of ages for HP-UHP rocks (a) and Paleozoic granitoids (b) in the NQOB, detrital zircons in the Liuling Group (c)
图 8 北秦岭早古生代构造演化简图
Fig. 8. Schematic cartoons showing the Early Paleozoic tectonic evolution of the North Qinling orogenic belt
-
Chen, D.L., Liu, L., 2011.New Data on the Chronology of Eclogite and Associated Rock from Guanpo Area, North Qinling Orogeny and Its Constraint on Nature of North Qinling HP-UHP Eclogite Terrane.Earth Science Frontiers, 18(2):158-169(in Chinese with English abstract). http://d.old.wanfangdata.com.cn/Periodical/dxqy201102014 Chen, D.L., Ren, Y.F., Gong, X.K., et al., 2015.Identification and Its Geological Significance of Eclogite in Songshugou, the North Qinling.Acta Petrologica Sinica, 31(7):1841-1854(in Chinese with English abstract). http://d.old.wanfangdata.com.cn/Periodical/ysxb98201507003 Cheng, H., Zhang, C., Vervoort, J.D., et al., 2011.Geochronology of the Transition of Eclogite to Amphibolite Facies Metamorphism in the North Qinling Orogen of Central China.Lithos, 125(3-4):969-983. https://doi.org/10.1016/j.lithos.2011.05.010 Cheng, H., Zhang, C., Vervoort, J.D., et al., 2012.Timing of Eclogite Facies Metamorphism in the North Qinling by U-Pb and Lu-Hf Geochronology.Lithos, 136-139:46-59. https://doi.org/10.1016/j.lithos.2011.06.003 Dong, Y.P., Santosh, M., 2016.Tectonic Architecture and Multiple Orogeny of the Qinling Orogenic Belt, Central China.Gondwana Research, 29(1):1-40. https://doi.org/10.1016/j.gr.2015.06.009 Dong, Y.P., Zhou, M.F., Zhang, G.W., et al., 2008.The Grenvillian Songshugou Ophiolite in the Qinling Mountains, Central China:Implications for the Tectonic Evolution of the Qinling Orogenic Belt.Journal of Asian Earth Sciences, 32:325-335. doi: 10.1016/j.jseaes.2007.11.010 Gong, X.K., 2017.Metamorphism, Composition and Formaiton Age of the Qinling Group in Danfeng Area(Dissertation).Northwest University, Xi'an(in Chinese with English abstract). Gong, X.K., Chen, D.L., Ren, Y.F., et al., 2016.Identification of Coesite-Bearing Amphibolite in the North Qinling and Its Geological Significance.Chinese Science Bulletin, 61(12):1365-1378(in Chinese). doi: 10.1360/N972015-01277 Liao, X.Y., 2018.Continental Deep Subduction-Exhumation Process of North Qinling Belt: Constraints on Early Paleozoic Tectonic Evolution(Dissertation).Northwest University, Xi'an(in Chinese with English abstract). Liao, X.Y., Liu, L., Wang, Y.W., et al., 2016.Multi-Stage Metamorphic Evolution of Retrograde Eclogite with a Granulite-Facies Overprint in the Zhaigen Area of the North Qinling Belt, China.Gondwana Research, 30:79-96. https://doi.org/10.1016/j.gr.2015.09.012 Liao, X.Y., Wang, Y.W., Liu, L., et al., 2017.Detrital Zircon U-Pb and Hf Isotopic Data from the Liuling Group in the South Qinling Belt:Provenance and Tectonic Implications.Journal of Asian Earth Sciences, 134:244-261. https://doi.org/10.1016/j.jseaes.2016.11.020 Liu, L., Liao, X.Y., Wang, Y.W., et al., 2016.Early Paleozoic Tectonic Evolution of the North Qinling Orogenic Belt in Central China:Insights on Continental Deep Subduction and Multiphase Exhumation.Earth-Science Reviews, 159:58-81. https://doi.org/10.1016/j.earscirev.2016.05.005 Liu, L., Liao, X.Y., Zhang, C.L., et al., 2013.Multi-Metamorphic Timing of HP-UHP Rocks in the North Qinling and Their Geological Implications.Acta Petrologica Sinica, 29(5):1634-1656(in Chinese with English abstract). Luo, F.H., Chen, D.L., Gong, X.K., et al., 2018.Multi-Stages Partial Melting of North Qinling Ultrahigh Pressure Metamorphic Terrane during Exhumation.Acta Petrologica Sinica, 34(12):3671-3689(in Chinese with English abstract). http://d.old.wanfangdata.com.cn/Periodical/ysxb98201812015 Wang, H., Wu, Y.B., Gao, S., et al., 2013.Continental Origin of Eclogites in the North Qinling Terrane and Its Tectonic Implications.Precambrian Research, 230:13-30. https://doi.org/10.1016/j.precamres.2012.12.010 Wang, H., Wu, Y.B., Gao, S., et al., 2014.Deep Subduction of Continental Crust in Accretionary Orogen:Evidence from U-Pb Dating on Diamond-Bearing Zircons from the Qinling Orogen, Central China.Lithos, 190-191:420-429. https://doi.org/10.1016/j.lithos.2013.12.021 Wang, Y.W., Liu, L., Liao, X.Y., et al., 2016.Multi-Metamorphism of Amphibolite in the Qinling Complex, Qingyouhe Area:Revelation from Trace Elements and Mineral Inclusions in Zircons.Acta Petrologica Sinica, 32(5):1467-1492(in Chinese with English abstract). http://d.old.wanfangdata.com.cn/Periodical/ysxb98201605015 Wu, Y.B., Zheng, Y.F., 2013.Tectonic Evolution of a Composite Collision Orogen:An Overview on the Qinling-Tongbai-Hong'an-Dabie-Sulu Orogenic Belt in Central China.Gondwana Research, 23(4):1402-1428. https://doi.org/10.1016/j.gr.2012.09.007 Yang, J.S., Xu, Z.Q., Pei, X.Z., et al., 2002.Discovery of Diamond in North Qinling:Evidence for a Giant UHPM Belt across Central China and Recognition of Paleozoic and Mesozoic Dual Deep Subduction between North China and Yangtze Plates.Acta Geologica Sinica, 76(4):484-495(in Chinese with English abstract). Zhang, A.D., Liu, L., Wang, Y., et al., 2003.Geochemistry and Tectonic Setting of the Protolith of Eclogites in North Qinling.Journal of Northwest University (Natural Science Edition), 33(2):191-195(in Chinese with English abstract). http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=xbdxxb200302018 Zhang, C.L., Liu, L., Wang, T., et al., 2013.Granitic Magmatism Related to Early Paleozoic Continental Collision in the North Qinling Belt.Chinese Science Bulletin, 58(23):2323-2329(in Chinese). doi: 10.1360/csb2013-58-23-2323 Zhang, G.W., Zhang, B.R., Yuan, X.C., et al., 2001.Qinling Orogenic Belt and Continental Dynamics.Science Press, Beijing(in Chinese). Zhang, H.F., Yu, H., Zhou, D.W., et al., 2015.The Meta-Gabbroic Complex of Fushui in North Qinling Orogen:A Case of Syn-Subduction Mafic Magmatism.Gondwana Research, 28(1):262-275. https://doi.org/10.1016/j.gr.2014.04.010 陈丹玲, 刘良, 2011.北秦岭榴辉岩及相关岩石年代学的进一步确定及其对板片俯冲属性的约束.地学前缘, 18(2):158-169. http://d.old.wanfangdata.com.cn/Periodical/dxqy201102014 陈丹玲, 任云飞, 宫相宽, 等, 2015.北秦岭松树沟榴辉岩的确定及其地质意义.岩石学报, 31(7):1841-1854. http://d.old.wanfangdata.com.cn/Periodical/ysxb98201507003 宫相宽, 2017.丹凤地区秦岭岩群物质组成、形成时代及变质作用研究(博士学位论文).西安: 西北大学. 宫相宽, 陈丹玲, 任云飞, 等, 2016.北秦岭含柯石英斜长角闪岩的发现及其地质意义.科学通报, 61(12):1365-1378. http://d.old.wanfangdata.com.cn/Conference/9135230 廖小莹, 2018.北秦岭陆壳深俯冲-折返作用及对早古生代构造演化过程的限定(博士学位论文).西安: 西北大学. 刘良, 廖小莹, 张成立, 等, 2013.北秦岭高压-超高压岩石的多期变质时代及其地质意义.岩石学报, 29(5):1634-1656. http://d.old.wanfangdata.com.cn/Periodical/ysxb98201305013 罗芬红, 陈丹玲, 宫相宽, 等, 2018.北秦岭超高压地体折返过程中的多期次部分熔融.岩石学报, 34(12):3671-3689. http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=ysxb98201812015 王亚伟, 刘良, 廖小莹, 等, 2016.秦岭杂岩清油河斜长角闪岩多期变质的证据:来自锆石微量元素和包裹体的启示.岩石学报, 32(5):1467-1492. http://d.old.wanfangdata.com.cn/Periodical/ysxb98201605015 杨经绥, 许志琴, 裴先治, 等, 2002.秦岭发现金刚石:横贯中国中部巨型超高压变质带新证据及古生代和中生代两期深俯冲作用的识别.地质学报, 76(4):484-495. doi: 10.3321/j.issn:0001-5717.2002.04.007 张安达, 刘良, 王焰, 等, 2003.北秦岭榴辉岩的地球化学特征及形成环境.西北大学学报(自然科学版), 33(2):191-195. doi: 10.3321/j.issn:1000-274X.2003.02.018 张成立, 刘良, 王涛, 等, 2013.北秦岭早古生代大陆碰撞过程中的花岗岩浆作用.科学通报, 58(23):2323-2329. http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=kxtb201323016 张国伟, 张本仁, 袁学诚, 等, 2001.秦岭造山带与大陆动力学.北京:科学出版社. -
下载:
点击查看大图
图(8)
计量
- 文章访问数: 4260
- HTML全文浏览量: 1730
- PDF下载量: 161
- 被引次数: 0
