南海中央海盆高精度地震勘探揭示的大陆漂移过程

doi:10.13745/j.esf.sf.2022.6.10-en

摘要/Abstract

摘要：

南海的形成和演化得到了广泛研究,前人提出了超过5种成因模式,当前流行是海底扩张模式,但它难以合理解释南海洋壳上的洋中脊跳跃和南海中央海盆上的大陆残片。本文首先基于南海中央海盆中的两条高精度地震勘探剖面,在深入剖析洋壳的分层结构基础上,对这两条地震勘探剖面进行了新的构造地质解释;然后通过伸展构造的形成过程,发展了地幔上涌和陆壳重力滑移双驱动大陆漂移模型;最后深入研究了南海的形成和演化过程。结果说明,南海的形成是一种“构造挤出+主动漂移”模式。构造挤出是印度-欧亚大陆碰撞造成的欧亚东南缘微陆块大规模被动挤出,而主动漂移是微陆块在被挤出后发生了主动裂解漂移。南海中央海盆上残留的地震反射特征,是微陆块主动漂移后造成的海底被扩张现象。并进一步恢复了南海演化过程中周边陆块的运动演化历史。所提出的新模式能够合理解释南海的洋中脊跳跃现象及大陆残片的成因机制。新大陆漂移模型为板块运动提供了一个新的动力模式。

关键词: 南海中央海盆, 南海成因, 高精度地震勘探, 动力机制, 大陆漂移

Abstract:

The formation and evolution of the South China Sea has been widely studied. More than five genetic models have been proposed. The current popular model is seafloor spreading, but it is difficult to reasonably explain the mid-ocean ridge jumping in South China Sea and the continental fragments found in the central basin of the South China Sea. First, based on two high precision seismic exploration sections in the central basin of the South China Sea, a new tectonic geological interpretation of the two seismic exploration sections was given on the basis of in-depth analysis of the layered structure of the oceanic crust. Then, through the formation process of extensional tectonics, the model of continental drift driven by mantle upwelling and continental crust gravity slip was developed. Finally, the formation and evolution process of the South China Sea was deeply studied. The results show that the formation of the South China Sea is a “tectonic extrusion + active drift” model. Tectonic extrusion is a large-scale passive extrusion of the microcontinents in the southeast margin of Eurasia plate caused by the India-Eurasia collision, while active drift is the active drift of the microcontinents after extrusion. The residual seismic reflection in the central basin of the South China Sea is a phenomenon of seafloor spreading caused by active drift of microcontinents. Furthermore, the geotectonic evolution of the microcontinents surrounding South China Sea was restored. The proposed new model can reasonably explain the phenomenon of mid-ocean ridge jumping in the South China Sea and the genetic mechanism of continental debris. The proposed new continent drift model provides a new dynamic model for plate movement.

Key words: central basin of South China Sea, genesis of South China Sea, high precision seismic exploration, dynamic mechanism, continental drift

中图分类号:

LIANG Guanghe. 南海中央海盆高精度地震勘探揭示的大陆漂移过程[J]. 地学前缘, 2023, 30(5): 430-449.

LIANG Guanghe. Continental drift process revealed by high precision seismic survey in the central basin of the South China Sea[J]. Earth Science Frontiers, 2023, 30(5): 430-449.

图/表 12

Fig.1 Tectonic background of the South China Sea and its surrounding areas. Adapted after [2]. BBWB—Beibu Bay Basin; LP—Leizhou Peninsula; MOR—Mid-ocean ridge; NPCT—North Palawan microblock; PRMB—Pearl River Mouth Basin; SSC—Huangyan Seamount chain; SWTB—Southwest Taiwan Basin.

Fig.2 Two seismic profiles in South China Sea. Modified after [7]. a is the profile position map; b is the N4-3 seismic exploration profile; c is the N3-2 seismic exploration profile.

Fig.3 Physical characteristics of ocean crust stratification. Modified after [37].

Fig.4 Geological interpretation of the N4-3 seismic exploration profile in the South China Sea. a is a simple geological interpretation of N4-3, adapted from [7]; b is the latest geological interpretation of N4-3.

Fig.5 Geological interpretation of N3-2. a is the seismic exploration profile of N3-2; b is the latest geological interpretation of N3-2.

Fig.6 Schematic diagram of extensional structure and gravity slip formed by mantle upwelling. a—Mantle upwelling causes extensional structure; b—Mantle upwelling causes gravity slip; c—After the continental block gravity slip, the depressurization behind it caused mantle melting upwelling and gravity slip again.

Fig.7 Schematic diagram of the new continent drift model, demonstrating the process is driven by mantle upwelling and gravitational slip

Fig.8 The “extrusion + drift” model of South China Sea

Fig.9 The Spreading process of the Continental margin of the South China Sea. Modified after [1].

Fig.10 One-direction continents drift model of South China Sea. a—The state of south China Continental margin and paleo SCS during 65 Ma; b—The state of 35 Ma; c—The current state of the South China Sea.

Fig.11 Schematic diagram of continental drift through N4-3 profile. a—Geological interpretation map of N4-3; b—The initial state of continental drift in this profile; c—Intermediate state of continental drift in this profile.

Fig.12 Schematic diagram of tectonic evolution in the South China Sea

参考文献 49

[1]	LUAN X W, ZHANG L. Tectonic evolution modes of South China Sea: passive spreading under complex actions[J]. Marine Geology and Quaternary Geology, 2009, 29(6): 59-74 (in Chinese with English abstract).
[2]	YU M M. Geochemical constraints on the opening and closing of the South China Sea[D]. Guangzhou: Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, 2018 (in Chinese with English abstract).
[3]	SUN L H, SUN Z, ZHANG Y Y, et al. Multi-stage carbonate veins at IODP Site U1504 document Early Cretaceous to Early Cenozoic extensional events on the South China Sea margin[J]. Marine Geology, 2021, 422: 106656.
[4]	TAPPONNIER P, PELTZER G, LEDAY, et al. Propagating extrusion tectonics in Asia New Insights from simple experiments with plasticine[J]. Geology, 1982, 10: 611-616. DOI URL
[5]	XIE J H, XIA B, ZHANG Y H, et al. Study on the effects of the India-Eurasia collision on the formation of the South China Sea: a numerical simulation approach[J]. Marine Science Bulletin, 2005, 24(5): 47-53 (in Chinese with English abstract).
[6]	KARIG D E. Origin and development of marginal basins in the western Pacific[J]. Journal of Geophysical Research, 1971, 76(11): 2542-2561. DOI URL
[7]	DING W W, SUN Z, KELSIE D, et al. Structures within the oceanic crust of the central South China Sea basin and their implications for oceanic accretionary processes[J]. Earth and Planetary Science Letters, 2018, 488: 115-125. DOI URL
[8]	HOLLOWAY N H. North Palawan block, Philippines: its relation to Asian mainland and role in evolution of South China Sea[J]. AAPG Bulletin, 1982, 66(9): 1355-1383.
[9]	RANGIN C, SPAKMAN W, PUBELLIER M, et al. Tomographic and geological constraints on subduction along the eastern Sundaland continental margin (South-East Asia)[J]. Bulletin de la Société Géologique de France, 1999, 170(6): 775-788.
[10]	ZHOU H, XIAO L, DONG V, et al. Geochemical and geochronological study of the Sanshui Basin bimodal volcanic rock suite, China: implications for basin dynamics in southeastern China[J]. Journal of Asian Earth Sciences, 2009, 34(2): 178-189. DOI URL
[11]	ZHANG G L, LUO Q, ZHAO J, et al. Geochemical nature of sub-ridge mantle and opening dynamics of the South China Sea[J]. Earth and Planetary Science Letters, 2018, 489: 145-155. DOI URL
[12]	GUO L Z, SHI Y S, MA R S. On the formation and evolution of the Mesozoic-Cenozoic active continental margin and island arc tectonic of the western Pacific Ocean[J]. Acta Geologica Sinica, 1983, 57(1): 13-23 (in Chinese with English abstract).
[13]	LIU Z S, YANG S K, HE S M, et al. The continental margin spreading of South China Sea and the cycle of evolution of marginal seas[J]. Tropic Oceanology, 1983, 2(4): 3-11 (in Chinese with English abstract).
[14]	CHENG D. The marginal extensional belt of East Asia continent: investigation the origin of a discrete continental margin[J]. Geotectonica et Metallogenia, 1997, 21(4): 285-293 (in Chinese with English abstract).
[15]	SHAO L, LI X H, WANG P X, et al. Sedimentary record of the tectonic evolution of the South China Sea since the Oligocene: evidence from deep sea sediments of ODP Site 1148[J]. Advances in Earth Science, 2004, 19(4): 539-544 (in Chinese with English abstract). DOI
[16]	LI C F, XU X, LIN J, et al. Ages and magnetic structures of the South China Sea constrained by deep tow magnetic surveys and IODP Expedition 349[J]. Geochemistry, Geophysics, Geosystems, 2014, 15(12): 4958-4983. DOI URL
[17]	QIU Y, CHEN G N, LIU F L, et al. Discovery of granite and its tectonic significance in southwestern basin of the South China Sea[J]. Geological Bulletin of China, 2008, 27(12): 2104-2107 (in Chinese with English abstract).
[18]	REN J S, XU Q Q, ZHAO L, et al. Looking for submerged landmasses[J]. Geological Review, 2015, 61(5): 969-989 (in Chinese with English abstract).
[19]	TAPPONNIER P, PELTZER G, ARMIJO R. On the mechanics of the collision between India and Asia[J]. Geological Society, London, Special Publications, 1986, 19: 113-157. DOI URL
[20]	WANG P X, JIAN Z M, Review and prospect of deep exploration in the South China Sea[J]. Scientia Sinica Terrae, 2019, 49(10): 1590-1606 (in Chinese with English abstract). DOI URL
[21]	HAYES D E, NISSEN S S. The South China sea margins: implications for rifting contrasts[J]. Earth and Planetary Science Letters, 2005, 237(3/4): 601-616. DOI URL
[22]	TAYLOR B, HAYES D E. Origin and history of the South China Basin[C]// HAYES D E. The tectonics and geologic evolution of Southeast Asian Seas and islands:Part 2. Geophysical monograph series. Washington: American Geophysical Union, 1983, 27: 23-56.
[23]	ZHANG G C, JIA Q J, WANG WY, et al. On tectonic framework and evolution of the South China Sea[J], Chinese Journal of Geophysics, 2018, 61(10): 4194-4215 (in Chinese with English abstract).
[24]	YAO B C, WAN L. Three-dimensional structure and evolution of lithosphere in South China Sea[M]. Beijing: Geological Publishing House, 2006:180-221.
[25]	OKAL E A, BERGEAL J M. Mapping the Miocene Farallon Ridge jump on the Pacific plate, a seismic line of weakness[J]. Earth and Planetary Science Letters, 1983, 63 (1), 113-122. DOI URL
[26]	DESCHAMPS A, FUJIWARA T. Asymmetric accretion along the slow spreading Mariana Ridge[J]. Geochemistry, Geophysics, Geosystems, 2013, 4(10): 8622. DOI:10.1029/2003GC0005370.
[27]	MISRA A A, SINHA N, MUKHERJEE S. Repeat ridge jumps and microcontinent separation: insights from NE Arabian Sea[J]. Marine and Petroleum Geology, 2015, 59 (59): 406-428. DOI URL
[28]	BRIAIS A, PATRIAT P, TAPPONNIER P. Updated interpretation of magnetic anomalies and seafloor spreading stages in the South China Sea: implications for the Tertiary tectonics of Southeast Asia[J]. Journal of Geophysical Research: Solid Earth, 1993, 98(B4): 6299-6328.
[29]	WANG P X. Tracing the life history of a marginal sea-On the “South China Sea Deep” research program[J]. Chinese Science Bulletin, 2012, 57(20): 1807-1826.
[30]	LU B Q. Introduction to marine geology[M]. Shanghai: Tongji University Press, 2008: 1-299.
[31]	CIAZELA J, KOEPKE J, DICK H J B, et al. Mantle rock exposures at oceanic core complexes along mid-ocean ridges[J]. Geologos, 2015, 21(4): 207-231. DOI URL
[32]	VITHANA M V P, XU M, ZHAO X, et al. Geological and geophysical signatures of the East Pacific Rise 8°-10°N[J]. Solid Earth Sciences, 2019, 4(2): 66-83. DOI URL
[33]	XU M, ZHAO X, CANALES J P. Structural variability within the Kane oceanic core complex from full waveform inversion and reverse time migration of streamer data[J]. Geophysical Research Letters, 2020. DOI: 10.1029/2020GL087405.
[34]	DICK H J B. Evidence for multi-stage melt transport in the lower ocean crust: the Atlantis bank gabbroic massif (IODPHole U1473A, SW Indian ridge)[J]. Journal of Petrology, 2020, 61(9): egaa082.
[35]	YU X, CHU F Y DONG Y H, et al Detachment fault and oceanic core complex: a new mode of seafloor spreading[J]. Earth Science, 2013, 38(5): 995-1004 (in Chinese with English abstract).
[36]	DIETZ R S. Continent and ocean basin evolution by spreading of the sea floor[J]. Nature, 1961, 190: 854-857. DOI
[37]	WU F Y, LIU C Z, ZHANG L L. et al. Yarlung Zangbo ophiolite: a critical updated view[J]. Acta Petrologica Sinica, 2014, 30: 293-325 (in Chinese with English abstract).
[38]	YU J H, YAN P, QIU Y, et al. Oceanic crustal structures and temporal variations of magmatic budget during seafloor spreading in the East Sub-basin of the South China Sea[J]. Marine Geology, 2021, 436: 106475. DOI:10.1016/j.margeo.2021.106475.
[39]	LIANG G H, YANG W R. Decipher the driving force in continental drift from new insights about the South Atlantic breakup process[J]. Earth Science Frontiers, 2022, 29(1): 1-14.
[40]	WANG E C. A discussion on the timing of the initial collision between the Indian and Asian continents[J]. Science China Earth Sciences, 2017, 47: 284-292 (in Chinese with English abstract).
[41]	FLOWER M, TAMAKI K, HOANG N. Mantle extrusion: a model for dispersed volcanism and Dupal-like asthenosphere in East Asia and the Western Pacific[C]. Washington: American Geophysical Union, 1998: 67-88.
[42]	LIU M, CUI X, LIU F. 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. DOI URL
[43]	MUTTER J C, KARSON J A. Structural processes at slow spreading ridges[J]. Science, 1992, 257: 627-634. DOI URL
[44]	ZHANG X H. One direction stretching and the formation of the South China Sea basin[J]. Marine Geology Letters, 1997, 5: 1-3 (in Chinese).
[45]	ZHANG X H, WANG Z L, HOU F H, et al. Terrain evolution of China seas and land since the Indo-China movement and characteristics of the stepped landform[J]. Chinese Journal of Geophysics, 2014, 57(12): 3968-3980 (in Chinese with English abstract).
[46]	LI Y H, HUANG H B, HE E Y, et al. Tectonic framework of miniature continental block-narrow oceanic basin revealed by the southern typical profile in the China seas-Western Pacific Ocean[J]. Chinese Journal of Geophysics, 2020, 63(5): 1938-1958 (in Chinese with English abstract).
[47]	XU Y G, HUANG X L, YAN W, et al. Constraints on the Cenozoic tectonic evolution of northern South China Sea(I): mantle-derived xenoliths[J]. Geochimica, 2002, 3: 230-242 (in Chinese with English abstract).
[48]	SUN J L, CAO J H, XU H L. Present-day crustal movement and focal mechanism solutions and plate interaction since late-Miocene in the eastern South China Sea[J]. Chinese Journal of Geophysics, 2014, 57(12): 4074-4084 (in Chinese with English abstract).
[49]	LIANG G H. Detailed study of the formation of Japanese islands based on tectonic evolution of basins in the East China Sea and northern South China Sea[J]. Earth Sciences Frontiers, 2020, 27(1): 244-259 (in Chinese with English abstract).