Crustal structure of the Cona rift, eastern Himalaya

doi:10.13745/j.esf.sf.2022.4.66

Abstract

Abstract:

The Himalayan mountain range is the result of continental-continental collision between the Indian and Eurasian plates. It has been under great debate as to why the rifts of southern Tibet are formed at the front of the collision zone. To answer this question, it is necessary to understand the crustal structure of the rifts. The age of each rift zone tends to be younger from west to east. In this study, we revealed the crustal structure of the Cona rift, a relatively young continental rift, using the P-wave receiver function calculated from teleseismic data received by a dense array across the rift, and analyzed the rift formation process based on the crustal structure. We showed that the Cona rift is a crustal-scale rift, where Moho offsets beneath the rift and significant lateral variations develops. We suggest that the formation of the rifts may be associated with regional tectonic activities, and further studies are needed to ascertain whether a single gravity collapse can form crustal-scale rifts. Based on the previous studies of magmatic rocks and geophysical observations, we infer that the asthenospheric upwelling caused by tearing of the subducting Indian plate weakened the lower crust of the Cona rift region where the middle and upper crust is also weakened as shown by the study of Himalayan leucogranites. Considering all the study results, we hypothesize that the formation of crustal-scale rift requires crustal weakening at different depths.

Key words: Cona rift, short-period dense array, receiver function, crustal weakening

CLC Number:

P315.2

WU Jiajie, XU Xiao, GUO Xiaoyu, LU Zhanwu, WU You, XIANG Bo, YU Yang, LI Chunsen, YU Jiahao, TONG Xiaofei, LUO Xucong. Crustal structure of the Cona rift, eastern Himalaya[J]. Earth Science Frontiers, 2022, 29(4): 221-230.

Figures/Tables 5

Fig.1 (a) Simplified geological map of and (b) distribution of NS-trending rifts (modified after [15-16]) in the Tibetan Plateau

Fig.2 (a) Topographic map of the study area showing the major tectonic features (modified from [8,23]) and (b) distribution of seismic stations and seismic events in the study area

Fig.3 Three-component seismogram for station 101

Fig.4 Receiver function stacking and migration imaging results for N-S profile

Fig.5 (a) N-S profile interpretation, (b) metamorphic p-T-t-D paths in the study area and (c,d) rift formation models.c modified after [55,63].

References 75

[1]	ENGLAND P, HOUSEMAN G. Extension during continental convergence, with application to the Tibetan Plateau[J]. Journal of Geophysical Research, 1989, 94(B12): 17561-17579.
[2]	DEWEY J F, BURKE K C A. Tibetan, Variscan, and Precambrian basement reactivation: products of continental collision[J]. The Journal of Geology, 1973, 81(6): 683-692.
[3]	HARRISON T M, COPELAND P, KIDD W, et al. Activation of the Nyainqentanghla shear zone: implications for uplift of the southern Tibetan Plateau[J]. Tectonics, 1995, 14(3): 658-676.
[4]	MOLNAR P, TAPPONNIER P. Cenozoic tectonics of Asia effects of a continental collision[J]. Science, 1975, 189(4201): 419-426.
[5]	COLEMAN M, HODGES K. Evidence for Tibetan plateau uplift before 14 Myr ago from a new minimum age for east-west extension[J]. Nature, 1995, 374(6517): 49-52.
[6]	张进江, 丁林, 钟大赉, 等. 喜马拉雅平行于造山带伸展: 是垮塌的标志还是挤压隆升过程的产物?[J]. 科学通报, 1999, 44(19): 2031-2036.
[7]	MOLNAR P, TAPPONNIER P. Active tectonics of Tibet[J]. Journal of Geophysical Research, 1978, 83(B11): 5361-5374.
[8]	吴中海, 张永双, 胡道功, 等. 西藏错那—拿日雍错地堑的第四纪正断层作用及其形成机制探讨[J]. 第四纪研究, 2008, 28(2): 232-242.
[9]	TAPPONNIER P, PELTZER G, LE DAIN A Y, et al. Propagating extrusion tectonics in Asia: new insights from simple experiments with plasticine[J]. Geology, 1982, 10(12): 611-616.
[10]	LEE J, WHITEHOUSE M J. Onset of mid-crustal extensional flow in southern Tibet: evidence from U/Pb zircon ages[J]. Geology, 2007, 35(1): 45-48.
[11]	YIN A. Mode of Cenozoic east-west extension in Tibet suggesting a common origin of rifts in Asia during the Indo-Asian collision[J]. Journal of Geophysical Research: Solid Earth, 2000, 105(B9): 21745-21759.
[12]	BIAN S, GONG J F, ZUZA A V, et al. Late Pliocene onset of the Cona rift, eastern Himalaya, confirms eastward propagation of extension in Himalayan-Tibetan orogen[J]. Earth and Planetary Science Letters, 2020, 544: 116383.
[13]	CHEN Y, LI W, YUAN X H, et al. Tearing of the Indian lithospheric slab beneath southern Tibet revealed by SKS-wave splitting measurements[J]. Earth and Planetary Science Letters, 2015, 413: 13-24.
[14]	LI J T, SONG X D. Tearing of Indian mantle lithosphere from high-resolution seismic images and its implications for lithosphere coupling in southern Tibet[J]. Proceedings of the National Academy of Sciences, 2018, 115(33): 8296-8300.
[15]	张佳伟, 李汉敖, 张会平, 等. 青藏高原新生代南北走向裂谷研究进展[J]. 地球科学进展, 2020, 35(8): 848-862. DOI
[16]	卞爽, 于志泉, 龚俊峰, 等. 青藏高原近南北向裂谷的时空分布特征及动力学机制[J]. 地质力学学报, 2021, 27(2): 178-194.
[17]	TIAN X B, CHEN Y, TSENG T L, et al. Weakly coupled lithospheric extension in southern Tibet[J]. Earth and Planetary Science Letters, 2015, 430: 171-177.
[18]	UNSWORTH M J, JONES A G, WEI W, et al. Crustal rheology of the Himalaya and Southern Tibet inferred from magnetotelluric data[J]. Nature, 2005, 438(7064): 78-81.
[19]	SHI D N, ZHAO W J, KLEMPERER S L, et al. West-east transition from underplating to steep subduction in the India-Tibet collision zone revealed by receiver-function profiles[J]. Earth and Planetary Science Letters, 2016, 452: 171-177.
[20]	SHI D N, WU Z H, KLEMPERER S L, et al. Receiver function imaging of crustal suture, steep subduction, and mantle wedge in the eastern India-Tibet continental collision zone[J]. Earth and Planetary Science Letters, 2015, 414: 6-15.
[21]	XU Q, ZHAO J M, YUAN X H, et al. Mapping crustal structure beneath southern Tibet: seismic evidence for continental crustal underthrusting[J]. Gondwana Research, 2015, 27(4): 1487-1493.
[22]	WANG G, WEI W B, YE G F, et al. 3-D electrical structure across the Yadong-Gulu rift revealed by magnetotelluric data: new insights on the extension of the upper crust and the geometry of the underthrusting Indian lithospheric slab in southern Tibet[J]. Earth and Planetary Science Letters, 2017, 474: 172-179.
[23]	DONG X Y, LI W H, LU Z W, et al. Seismic reflection imaging of crustal deformation within the eastern Yarlung-Zangbo suture zone[J]. Tectonophysics, 2020, 780: 228395.
[24]	LIANG X F, CHEN Y, TIAN X B, et al. 3D imaging of subducting and fragmenting Indian continental lithosphere beneath southern and central Tibet using body-wave finite-frequency tomography[J]. Earth and Planetary Science Letters, 2016, 443: 162-175.
[25]	CHUNG S L, CHU M F, ZHANG Y Q, et al. Tibetan tectonic evolution inferred from spatial and temporal variations in post-collisional magmatism[J]. Earth-Science Reviews, 2005, 68(3/4): 173-196.
[26]	张进江, 丁林. 青藏高原东西向伸展及其地质意义[J]. 地质科学, 2003, 38(2): 179-189.
[27]	赵志丹, 莫宣学, NOMADE S, 等. 青藏高原拉萨地块碰撞后超钾质岩石的时空分布及其意义[J]. 岩石学报, 2006, 22(4): 787-794.
[28]	陈建林, 许继峰, 王保弟, 等. 青藏高原拉萨地块新生代超钾质岩与南北向地堑成因关系[J]. 岩石矿物学杂志, 2010, 29(4): 341-354.
[29]	BURG J P, GUIRAUD M, CHEN G M, et al. Himalayan metamorphism and deformations in the North Himalayan Belt (southern Tibet, China)[J]. Earth and Planetary Science Letters, 1984, 69(2): 391-400.
[30]	SCHNEIDER D A, EDWARDS M A, KIDD W S F, et al. Early Miocene anatexis identified in the western syntaxis, Pakistan Himalaya[J]. Earth and Planetary Science Letters, 1999, 167(3/4): 121-129.
[31]	林彬, 唐菊兴, 郑文宝, 等. 西藏错那洞淡色花岗岩地球化学特征、成岩时代及岩石成因[J]. 岩石矿物学杂志, 2016, 35(3): 391-406.
[32]	吴中海, 张永双, 胡道功, 等. 西藏错那—沃卡裂谷带中段邛多江地堑晚新生代正断层作用[J]. 地质力学学报, 2007, 13(4): 297-306.
[33]	洛桑尖措, 卿成实, 李光明, 等. 西藏山南地区错那洞穹窿岩石地球化学异常特征[J]. 物探与化探, 2020, 44(1): 13-24.
[34]	张进江, 郭磊, 张波. 北喜马拉雅穹隆带雅拉香波穹隆的构造组成和运动学特征[J]. 地质科学, 2007, 42(1): 16-30.
[35]	曾令森, 刘静, 高利娥, 等. 藏南也拉香波穹隆早渐新世地壳深熔作用及其地质意义[J]. 科学通报, 2008, 54(3): 104-112.
[36]	BURCHFIEL B C, CHEN Z L, HODGES K V, et al. The south Tibetan detachment system, Himalayan orogen: extension contemporaneous with and parallel to shortening in a collisional mountain belt[M]//Boulder Geological Society of America Special Papers, 1992, 269: 1-41.
[37]	BURG J, BRUNEL M, GAPAIS D, et al. Deformation of leucogranites of the crystalline main central Sheet in southern Tibet (China)[J]. Journal of Structural Geology, 1984, 6(5): 535-542.
[38]	YIN A. Cenozoic tectonic evolution of the Himalayan orogen as constrained by along-strike variation of structural geometry, exhumation history, and foreland sedimentation[J]. Earth-Science Reviews, 2006, 76(1/2): 1-131.
[39]	陈智梁, 刘宇平. 藏南拆离系[J]. 特提斯地质, 1996, 20: 31-51.
[40]	董汉文, 许志琴, 孟元库, 等. 藏南错那洞淡色花岗岩年代学研究及其对藏南拆离系活动时间的限定[J]. 岩石学报, 2017, 33(12): 3741-3752.
[41]	SWEET J R, ANDERSON K R, BILEK S, et al. A community experiment to record the full seismic wavefield in Oklahoma[J]. Seismological Research Letters, 2018, 89(5): 1923-1930.
[42]	PORRITT R W, MILLER M S. Updates to FuncLab, a Matlab based GUI for handling receiver functions[J]. Computers & Geosciences, 2018, 111(1): 260-271.
[43]	NELSON K D, ZHAO W, BROWN L D, et al. Partially molten middle crust beneath southern Tibet: synthesis of project INDEPTH results[J]. Science, 1996, 274(5293): 1684-1688.
[44]	SHI D N, KLEMPERER S L, SHI J Y, et al. Localized foundering of Indian lower crust in the India-Tibet collision zone[J]. Proceedings of the National Academy of Sciences, 2020, 117(40): 24742-24747.
[45]	HOU Z Q, YANG Z M, LU Y J, et al. A genetic linkage between subduction- and collision-related porphyry Cu deposits in continental collision zones[J]. Geology, 2015, 43(3): 247-250.
[46]	侯增谦, 赵志丹, 高永丰, 等. 印度大陆板片前缘撕裂与分段俯冲: 来自冈底斯新生代火山-岩浆作用证据[J]. 岩石学报, 2006, 22(4): 761-774.
[47]	ZHANG L Y, DUCEA M N, DING L, et al. Southern Tibetan oligocene-miocene adakites: a record of Indian slab tearing[J]. Lithos, 2014, 210: 209-223.
[48]	WANG W, ZENG L S, GAO L E, et al. Eocene-Oligocene potassic high Ba-Sr granitoids in the Southeastern Tibet: petrogenesis and tectonic implications[J]. Lithos, 2018, 322: 38-51.
[49]	GUO Z F, WILSON M. Late Oligocene-early Miocene transformation of postcollisional magmatism in Tibet[J]. Geology, 2019, 47(8): 776-780.
[50]	YIN A, HARRISON T M. Geologic evolution of the Himalayan-Tibetan orogen[J]. Annual Review of Earth and Planetary Sciences, 2000, 28(1): 211-280.
[51]	LIU Z, TIAN X B, YUAN X H, et al. Complex structure of upper mantle beneath the Yadong-Gulu rift in Tibet revealed by S-to-P converted waves[J]. Earth and Planetary Science Letters, 2020, 531: 1-9.
[52]	YIN A, TAYLOR M H. Mechanics of V-shaped conjugate strike-slip faults and the corresponding continuum mode of continental deformation[J]. Geological Society of America Bulletin, 2011, 123(9/10): 1798-1821.
[53]	YANG Y J, RITZWOLLER M H, ZHENG Y, et al. A synoptic view of the distribution and connectivity of the mid-crustal low velocity zone beneath Tibet[J]. Journal of Geophysical Research: Solid Earth, 2012, 117(B4): 1-20.
[54]	WU F Y, LIU X C, LIU Z C, et al. Highly fractionated Himalayan leucogranites and associated rare-metal mineralization[J]. Lithos, 2020, 352: 105319.
[55]	ZHANG Z M, XIANG H, DONG X, et al. Oligocene HP metamorphism and anatexis of the higher himalayan crystalline sequence in Yadong region, east-central Himalaya[J]. Gondwana Research, 2017, 41: 173-187.
[56]	BEAUMONT C, JAMIESON R A, NGUYEN M H, et al. Himalayan tectonics explained by extrusion of a low-viscosity crustal channel coupled to focused surface denudation[J]. Nature, 2001, 414(6865): 738-742.
[57]	RUBATTO D, CHAKRABORTY S, DASGUPTA S. Timescales of crustal melting in the Higher Himalayan Crystallines (Sikkim, Eastern Himalaya) inferred from trace element-constrained monazite and zircon chronology[J]. Contributions to Mineralogy and Petrology, 2012, 165(2): 349-372.
[58]	JAMIESON R A, BEAUMONT C, NGUYEN M H, et al. Provenance of the Greater Himalayan Sequence and associated rocks: predictions of channel flow models[J]. Geological Society, London, Special Publications, 2006, 268(1): 165-182.
[59]	BEAUMONT C, JAMIESON R A, NGUYEN M H, et al. Crustal channel flows: 1. Numerical models with applications to the tectonics of the Himalayan-Tibetan orogen[J]. Journal of Geophysical Research: Solid Earth, 2004, 109(B6): 1-29.
[60]	ARSLAN A, PASSCHIER C W, KOEHN D. Foliation boudinage[J]. Journal of Structural Geology, 2008, 30(3): 291-309.
[61]	WEBB A A G, SCHMITT A K, HE D, et al. Structural and geochronological evidence for the leading edge of the Greater Himalayan Crystalline complex in the central Nepal Himalaya[J]. Earth and Planetary Science Letters, 2011, 304(3/4): 483-495.
[62]	CAROSI R, MONTOMOLI C, IACCARINO S, et al. Middle to late eocene exhumation of the greater himalayan sequence in the central Himalayas: progressive accretion from the Indian plate[J]. Geological Society of America Bulletin, 2016, 128(11/12): 1571-1592.
[63]	WANG J M, WU F Y, RUBATTO D, et al. Early Miocene rapid exhumation in southern Tibet: insights from p-T-t-D-magmatism path of Yardoi dome[J]. Lithos, 2018, 304-307: 38-56.
[64]	GRUJIC D, CASEY M, DAVIDSON C, et al. Ductile extrusion of the Higher Himalayan Crystalline in Bhutan: evidence from quartz microfabrics[J]. Tectonophysics, 1996, 260(1/2/3): 21-43.
[65]	GUO Z F, WILSON M. The Himalayan leucogranites: constraints on the nature of their crustal source region and geodynamic setting[J]. Gondwana Research, 2012, 22(2): 360-376.
[66]	HARRISON M T, GROVE M, MCKEEGAN K D, et al. Origin and episodic emplacement of the Manaslu Intrusive complex, central Himalaya[J]. Journal of Petrology, 1999, 40(1): 3-19.
[67]	GUILLOT S, LE FORT P. Geochemical constraints on the bimodal origin of high himalayan leucogranites[J]. Lithos, 1995, 35(3/4): 221-234.
[68]	张泽明, 康东艳, 丁慧霞, 等. 喜马拉雅造山带的部分熔融与淡色花岗岩成因机制[J]. 地球科学, 2018, 43(1): 82-98.
[69]	WU F Y, LIU Z C, LIU X C, et al. Himalayan leucogranite: petrogenesis and implications to orogenesis and plateau uplift[J]. Acta Petrologica Sinica, 2015, 31(1): 1-36.
[70]	贺日政, 高锐. 西藏高原南北向裂谷研究意义[J]. 地球物理学进展, 2003, 18(1): 35-43.
[71]	TAPPONNIER P, PELTZER G, DAIN A, et al. Propagating extrusion tectonics in Asia: new insights from simple experiments with plasticine[J]. 1982, 10(12): 611.
[72]	郑文俊, 张培震, 袁道阳, 等. 中国大陆活动构造基本特征及其对区域动力过程的控制[J]. 地质力学学报, 2019, 25(5): 699-721.
[73]	TIAN Z, YANG Z Q, BENDICK R, et al. Present-day distribution of deformation around the southern Tibetan Plateau revealed by geodetic and seismic observations[J]. Journal of Asian earth sciences, 2019, 171: 321-333.
[74]	YIN A. Mode of Cenozoic east-west extension in Tibet suggesting a common origin of rifts in Asia during the Indo-Asian collision[J]. Journal of Geophysical Research: Solid Earth, 2000, 105(B9): 21745-21759.
[75]	LIU M, CUI X J, LIU F T. Cenozoic rifting and volcanism in eastern China: a mantle dynamic link to the Indo-Asian collision?[J]. Tectonophysics, 2004, 393(1/2/3/4): 29-42.