印度大陆板块北漂的动力机制研究

doi:10.13745/j.esf.2020.1.23

摘要/Abstract

摘要：

印度大陆板块是一个活化的克拉通板块,其向北漂移并与欧亚板块碰撞过程得到了广泛研究,但其北漂的动力机制则很少被关注。传统上认为是海底扩张造成了印度大陆板块的北漂,但最新的地球物理观测结果却与此相悖。基于地磁场异常特征、古地磁测量和地震勘探剖面等诸多证据的系统分析研究,结果表明印度大陆板块厚度大约40 km,其北漂的动力机制与印度板块南侧深部的岩浆上涌密切相关,大陆板块的漂移是自发驱动的。通过新建立的大陆漂移模型可以合理解释印度大陆板块漂移的动力来源,并合理地解释了印度大陆板块北漂中伴随左旋的深层次动力机制。最后探讨了印度大陆板块在80~40 Ma期间异常高速漂移的根源和东非大裂谷的成因。本研究为大陆漂移模式提供了一个新的动力机制。

关键词: 印度大陆板块, 大陆漂移, 动力机制, 东非裂谷, 海底扩张

Abstract:

The Indian continental plate is an activated cratonic plate. Its northward drift and collision with Eurasian plate have been extensively studied, however, the dynamic mechanism of the northward drift is rarely noticed. Traditionally, it is believed that the sea-floor spreading caused the northward drift of the Indian Plate, but the latest geophysical observations are contrary to this belief. Based on systematic analyses of geomagnetic anomaly characteristics, paleomagnetic measurements and seismic exploration profiles, we showed that the thickness of the Indian continental plate is about 40 km. We established a new continental drift model to illustrate that the dynamic mechanism of the northward drift is closely related to the continuous deep magma upwelling in the south part of the Indian Plate, such that the northward drift is self driven. This model can reasonably explain the power source of the Indian Plate drift; and it can also give a reasonable explanation about the dynamic mechanism of the left-lateral rotation of the Indian Plate. Finally, we discussed the origin of the abnormal high-speed drift of the Indian Plate between 80-40 Ma and the cause of the Great Rift Valley in East Africa. This study provides a new dynamic mechanism for the continental drift model.

Key words: Indian continental plate, continental drift, dynamic mechanism, East African rift, sea-floor spreading

中图分类号:

P541

梁光河. 印度大陆板块北漂的动力机制研究[J]. 地学前缘, 2020, 27(1): 211-220.

LIANG Guanghe. Study on the dynamic mechanism of northward drift of the Indian Plate[J]. Earth Science Frontiers, 2020, 27(1): 211-220.

图/表 11

图1 印度洋盆及周缘大地构造略图(据文献[10]) 1—马斯克林洋底高原;2—马达加斯加微陆块;3—马达加斯加洋底高原;4—莫桑比克微陆块;5—厄加勒斯微陆块;6—马里昂洋底高原;7—Conrad海隆;8—克洛泽洋底高原;9—Elan Bank微陆块;10—凯尔盖朗洋底高原;11—Broken脊;12—纳多鲁列斯微陆块;13—Cuvier微陆块;14—Exmouth微陆块;15—东经90°E海岭;16—查戈斯海岭;LLSVP—超级地幔柱

Fig.1 Tectonic sketch map of the Indian Ocean. Adapted from [10].

图2 印度洋地区磁异常图(据文献[11])

Fig.2 Map showing magnetic anomaly in the Indian Ocean. Adapted from [11].

图3 全球地壳厚度分布图

Fig.3 Global spatial distribution of crustal thickness

图4 新大陆漂移模型(据文献[23,24])

Fig.4 A new continental drift model. Adapted from [23-24].

图5 印度大陆板块的漂移历史和轨迹 a—大西洋裂解前的状态;b,c—根据古地磁测量得到的印度大陆板块随时间纬度变化[1];d—印度大陆板块漂移历史示意图。

Fig.5 History and trajectory of Indian Plate drift

图6 印度近海地区高精度人工地震勘探剖面A及简单地质解译 a—剖面的实施位置;b—该剖面在新大陆漂移模型中的位置;c—该地震勘探剖面及地质解译;黑色箭头表示正断层上盘下降方向。

Fig.6 A simplified geological interpretation of high-precision seismic exploration section A in the offshore region of India

图7 印度近海地区高精度人工地震勘探剖面B及简单地质解译 a—剖面的实施位置;b—该剖面在新大陆漂移模型中的位置;c—该地震勘探剖面及地质解译。

Fig.7 A simplified geological interpretation of high-precision seismic exploration section B in the offshore area of India

图8 印度近海地区高精度人工地震勘探剖面C及简单地质解译 a—剖面的实施位置;b—该剖面在新大陆漂移模型中的位置;c—该地震勘探剖面及地质解译。

Fig.8 A simplified geological interpretation of high-precision seismic exploration section C in the offshore area of India

图9 基于地震勘探剖面得到的印度大陆板块漂移动力机制模式图

Fig.9 Schematic diagram of the dynamic mechanism for the Indian Plate drift based on the seismic exploration profiles

图10 中国大陆及邻区地壳现今速度场GPS测量结果(据文献[27])

Fig.10 GPS survey results of the current crustal velocity field in China and neighboring regions. Adapted from [27]

图11 印度大陆板块漂移路线及东非裂谷成因机制示意图

Fig.11 Schematic diagram showing the Indian Plate drift route and genetic mechanism of the East African Rift

参考文献 29

[1]	GARY A. G. Geomagnetism[M]. Santa Cruz: Press of University of California, 2013.
[2]	VEEVERS J J, MCELHINNY M W. The separation of Australia from other continents[J]. Earth Science Reviews, 1976, 12(2/3):139-143. DOI URL
[3]	袁学诚, 李廷栋, 肖序常, 等. 青藏高原岩石圈三维结构及高原隆升的液压机模型[J]. 中国地质, 2006, 33(4):711-729.
[4]	李德威. 青藏高原隆升机制新模式[J]. 地球科学, 2003, 28(6):593-600.
[5]	高锐, 李廷栋, 吴功建. 青藏高原岩石圈演化与地球动力学过程: 亚东—格尔木—额济纳旗地学断面的启示[J]. 地质论评, 1998, 44(4):389-395.
[6]	王二七. 关于印度与欧亚大陆初始碰撞时间的讨论[J]. 中国科学: 地球科学, 2017, 47:284-292.
[7]	AITCHISON J C, ALI J R, DAVIS A M. When and where did India and Asia collide?[J]. Journal of Geophysical Research, 2007, 112(B5):B05423. https://doi.org/10.1029/2006JB004706
[8]	SUO Y H, LI S Z, YU S, et al. Morphotectonics and ridge jumpings in Indian Ocean[J]. Geological Journal, 2016, 51(Suppl 1):624-633. DOI URL
[9]	YOSHIDA M, SANTOSH M. Voyage of the Indian subcontinent since Pangea breakup and driving force of supercontinent cycles: insights on dynamics from numerical modeling[J]. Geoscience Frontiers, 2018, 9:1279-1292. DOI URL
[10]	李江海, 张华添, 李洪林. 印度洋大地构造背景及其构造演化: 印度洋底大地构造图研究进展[J]. 海洋学报, 2015, 37(7):1-14.
[11]	KOEHONEN J V, FAIRHEAD J D, HAMOUDI M, et al. Magnetic anomaly map of the world, scale: 1∶50000000[M]. Paris: Commission for the Geological Map of the World, 2017.
[12]	DOMINQUE W, STEPHANIE I, DIMITRI D, et al. Origin of continental components in Indian Ocean basalts: evidence from Elan Bank (Kerguelen Plateau ODP Leg 183 Site 1137)[J]. Geology, 2001, 29(2):147-150. DOI URL
[13]	STOREY B C. The role of mantle plumes in continental breakup: case histories from Gondwanaland[J]. Nature, 1995, 377(6547):301-308. DOI URL
[14]	TODAL A, ELDHOLM O. Continental margin off western India and Deccan large igneous province[J]. Marine Geophysical Researches, 1998, 20(4):273-291. DOI URL
[15]	CHENG H, ZHOU H Y, YANG Q H, et al. Jurassic zircons from the Southwest Indian Ridge [J/OL]. Scientific Reports, 2016, 6:26260. DOI: 10.1038/srep26260.
[16]	JACKSON J. Strength of the continental lithosphere: time to aband on the jelly sandwich?[J]. GSA Today, 2002, 12:4-9.
[17]	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. DOI URL
[18]	ROGER B, REBECCA B, KALI W. Flexure of the Indian Plate and intraplate earthquakes[J]. Proceedings of the Indian Academy of Sciences (Earth Planet), 2003, 112(3):315-329.
[19]	陈国能, 王勇, 陈震, 等. 花岗岩浆形成定位机制的思考与研究进展[J]. 岩石学报, 2017, 33(5):1489-1497.
[20]	国家自然科学基金委员会, 中国科学院. 板块构造与大陆动力学[M]. 北京: 科学出版社, 2017.
[21]	TURCITTE D L, SCHUBERT G. Geodynamics[M]. 2nd ed. Cambridge: Cambridge University Press, 2002.
[22]	ZHENG Y F. Fifty years of plate tectonics[J]. National Science Review, 2018, 5(2):119-119. https://doi.org/10.1093/nsr/nwy024 DOI URL
[23]	梁光河. 大陆漂移的源动力:板块自驱动模式[J]. 地球科学前沿, 2013, 3:86-96.
[24]	梁光河. 新大陆漂移模型与地震成因关系研究[J]. 科学技术与工程, 2018, 18(28):47-57.
[25]	MOLNAR P, TAPPONIER P. Active tectonics of Tibet[J]. Journal of Geophysical Research, 1978, 83:5361-5375. DOI URL
[26]	ION. Seismic exploration in the Indian marginal sea [C] //EAGE. Research Report on 76th Annual Meeting of European Geophysicists and Engineers. Amsterdam, 2014: 5-8.
[27]	李强, 游新兆, 杨少敏, 等. 中国大陆构造变形高精度大密度GPS监测:现今速度场[J]. 中国科学:D辑, 2012, 42(5):629-632.
[28]	ZHENG G, WANG H, WRIGHT T J, et al. Crustal deformation in the India-Eurasia collision zone from 25 years of GPS measurements[J]. Journal of Geophysical Research: Solid Earth, 2017, 122:9290-9312. https://doi.org/10.1002/2017JB014465 DOI URL
[29]	KUMAR P, YUAN X H, KUMAR M R, et al. The rapid drift of the Indian tectonic plate[J]. Nature, 2007, 449:894-897. DOI URL