汇聚背景下的多幕裂陷作用及其迁移机制:以南海北部珠江口盆地为例

doi:10.13745/j.esf.sf.2022.3.29

摘要/Abstract

摘要：

南海的形成演化受控于印-澳、欧亚以及太平洋板块的相互运动,为研究汇聚背景下板块碰撞及其远程效应提供重要窗口。为了揭示该汇聚背景下的多幕裂陷过程,本文选取地质信息丰富的整个珠江口盆地为典型区,利用三条高精度地震剖面,对盆地各地质单元进行断层活动速率和构造沉降速率的定量计算及综合分析。结果表明盆地裂陷期东部、中部和西部主要控凹断层的平均活动速率分别为96 m/Ma、223 m/Ma和124 m/Ma,且其平均沉降速率依次为8.5 m/Ma、34 m/Ma和12.7 m/Ma,盆地整体呈现中部裂陷作用最强,其后向西部和东部逐渐减弱的特征。本文认为这与先存断裂以及初始地壳厚度有关:盆地东部和中部存在NE向先存断裂,并且东部先存断裂更加活跃,因此在新生代拉伸应力下东部更易表现为裂陷作用最强的区域,其次为中部和西部;而受前新生代时期俯冲作用的影响,岩浆的底垫作用引起盆地东部地壳增厚,东部裂陷作用强度急剧降低,造成裂陷作用强度的东西差异。此外,盆地南段凹陷裂陷期的断层活动和沉降速率发生激增,裂陷作用存在向南迁移的现象。本文推测在深度相关的伸展模式的影响下,南段凹陷地壳温度升高,强度减弱,因而在伸展应力下发生快速的拉伸减薄,导致裂陷中心向南迁移及岩浆物质上涌。同时,侵入的岩浆物质导致高角度正断层转换成低角度正断层,进一步促进裂陷中心向南迁移。

关键词: 珠江口盆地, 多幕裂陷作用, 迁移机制, 断层活动速率, 构造沉降

Abstract:

The formation and evolution of the South China Sea is controlled by the mutual movements of the Indo-Australian, Eurasian and Pacific plates, which provides an important window for the study of plate collisions and their long-range effects in the context of plate convergence. To reveal the multi-episodic rifting process under this context, we select the entire Pearl River Mouth Basin rich in geologic information as the typical area of South China, and used three high-precision seismic sections to calculate the fault activity and tectonic subsidence rates and perform comprehensive analysis for each geological unit in the basin. According to our calculation, the average fault activity rates for the main sag-controlling faults of the eastern, central and western parts of the basin during the rifting period were 85, 203 and 93 m/Ma, respectively, and the average subsidence rates were 8.5, 34 and 12.7 m/Ma, respectively. Basinwide, rifting was strongest in the center and gradually weakened to the west and east, which, we believe, is related to the pre-existing faults and initial crustal thickness. The pre-existing NE-trending faults are known to be more active in the east than in the center. Therefore, under Cenozoic tensile stress, the east is more likely to experience the strongest rifting, followed by the center then the west. Whilst under the influence of pre-Cenozoic subduction, magmatic underplating caused the crust to thicken thus rifting intensity to drop sharply in the east, resulting in the difference in rifting intensity between west and east. In addition, the fault activity and subsidence rates in southern basin had surged during the rifting period, causing rifting to migrate to the south. We speculated that under the influence of depth-dependent extension, the southern sag witnessed increased crustal temperature and weakened crustal strength. As a result, rapid tensile thinning occurred under extensional stress, resulting in a southward migration of the rift center accompanied by mantle upwelling. At the same time, intrusive magmatic material caused the high-angle normal fault to convert into a low-angle normal fault, further promoting the southward migration of the rift center.

Key words: Pearl River Mouth Basin, multiphase rift, migration mechanism, fault activity rate, tectonic subsidence

中图分类号:

詹诚, 卢绍平, 方鹏高. 汇聚背景下的多幕裂陷作用及其迁移机制:以南海北部珠江口盆地为例[J]. 地学前缘, 2022, 29(4): 307-318.

ZHAN Cheng, LU Shaoping, FANG Penggao. Multiphase rift and migration mechanism in the Pearl River Mouth Basin[J]. Earth Science Frontiers, 2022, 29(4): 307-318.

图/表 7

图1 珠江口盆地区域地质图

Fig.1 Regional geological map of the Pearl River Mouth Basin

图2 珠江口盆地新生代构造-地层格架图(据文献[19,23])

Fig.2 Cenozoic structural-stratigraphic framework of the Pearl River Mouth Basin. Adapted from [19,23].

图3 珠江口盆地东部、中部与西部地震剖面(a,b,c,d据文献[18]; e据文献[17])

Fig.3 Seismic profiles of the eastern, central and western Pearl River Mouth Basin. a-d adapted from [18]; e adapted from [17].

图4 珠江口盆地东部裂陷期断层活动速率(a)、构造沉降速率(b)以及地震剖面图(c) 虚线划分凹陷以及隆起,误差棒代表结果的误差范围。

Fig.4 Fault activity (a) and tectonic subsidence (b) rates for and seismic profile (c) of the eastern Pearl River Mouth Basin during the rifting period

图5 珠江口盆地中部裂陷期断层活动速率(a)、构造沉降速率(b)以及地震剖面图(c) 虚线划分凹陷以及隆起,误差棒代表结果的误差范围。

Fig.5 Fault activity (a) and tectonic subsidence (b) rates for and seismic profile of the central Pearl River Mouth Basin during the rifting period

图6 珠江口盆地西部裂陷期断层活动速率(a)、构造沉降速率(b)以及地震剖面图(c) 虚线划分凹陷以及隆起,误差棒代表结果的误差范围。

Fig.6 Fault activity (a) and tectonic subsidence (b) rates for and seismic profile of the western Pearl River Mouth Basin during the rifting period

表1 珠江口盆地东部、中部与西部主要控凹断层的活动速率

Table 1 Fault activity rates for major sag-controlling faults in the eastern, central and western parts of the Pearl River Mouth Basin

位置	断层序号	构造沉降速度/(m·Ma^-1)
位置	断层序号	裂陷一幕	裂陷二幕
东部	E-f3	168.23	58.29
	E-f9	0	71
	E-f11	0	88
中部	M-f8	199.53	182.04
	M-f21	95.68	499.27
	M-f23	157.02	361.15
	M-f26	0	236.06
	M-f31	88.05	190.31
西部	W-f6	67.84	190
	W-f11	107.19	115
	W-f15	0	182.67
	W-f16	108	140
	W-f17	139	71

参考文献 61

[1]	钟志洪, 施和生, 朱明, 等. 珠江口盆地构造[J]. 中国海上油气, 2014, 26(5): 20-29.
[2]	毛云华, 赵中贤, 孙珍, 等. 珠江口盆地西部陆缘伸展-减薄机制[J]. 地球科学, 2020, 45(5): 146-159.
[3]	施和生, 于水明, 梅廉夫, 等. 珠江口盆地惠州凹陷古近纪幕式裂陷特征[J]. 天然气工业, 2009, 29(1): 35-37.
[4]	吴培康. 南海北部多幕裂陷作用与含油气系统[J]. 石油学报, 1998, 19(3): 11-15. DOI
[5]	王维, 叶加仁, 杨香华, 等. 珠江口盆地惠州凹陷古近纪多幕裂陷旋回的沉积物源响应[J]. 地球科学, 2015, 40(6): 1061-1071.
[6]	HAO S, MEI L, SHI H, et al. Rift migration and transition during multiphase rifting: insights from the proximal domain, northern South China Sea rifted margin[J]. Marine and Petroleum Geology, 2021, 123: 104729.
[7]	葛家旺, 朱筱敏, 雷永昌, 等. 多幕裂陷盆地构造-沉积响应及陆丰凹陷实例分析[J]. 地学前缘, 2021, 28(1): 77-89. DOI
[8]	ZHU H, LI S, SHU Y, et al. Applying seismic geomorphology to delineate switched sequence stratigraphic architecture in lacustrine rift basins: an example from the Pearl River Mouth Basin, northern South China Sea[J]. Marine and Petroleum Geology, 2016, 78: 785-796.
[9]	崔莎莎, 何家雄, 陈胜红, 等. 珠江口盆地发育演化特征及其油气成藏地质条件[J]. 天然气地质学, 2009, 20(3): 384-391.
[10]	HE M, ZHONG G, LIU X, et al. Rapid post-rift tectonic subsidence events in the Pearl River Mouth Basin, Northern South China Sea margin[J]. Journal of Asian Earth Sciences, 2017, 147: 271-283.
[11]	姚伯初. 南海新生代的构造演化与沉积盆地[J]. 南海地质研究, 1998, 10: 1-17.
[12]	陈汉宗, 吴湘杰, 周蒂, 等. 珠江口盆地中新生代主要断裂特征和动力背景分析[J]. 热带海洋学报, 2005, 24(2): 52-61.
[13]	刘海伦, 梅廉夫, 施和生, 等. 珠江口盆地珠一坳陷裂陷结构: 基底属性与区域应力联合制约[J]. 地球科学, 2018(3): 1-17.
[14]	MARUYAMA S, SEND T. Orogeny and Relative Plate Motions: example of the Japanese Islands[J]. Tectonophysics, 1986, 127(3): 305-329.
[15]	HALL Robert. Late Jurassic-Cenozoic reconstructions of the Indonesian region and the Indian Ocean[J]. Tectonophysics, 2012, 570/571: 1-41.
[16]	赵中贤, 周蒂, 廖杰. 珠江口盆地第三纪古地理及沉积演化[J]. 热带海洋学报, 2009, 28(6): 52-60.
[17]	杨林龙. 南海北部陆缘大型拆离断层系的发育演化机制及其对深水盆地群的控制作用[D]. 武汉: 中国地质大学(武汉), 2018: 1-149.
[18]	XIE X, REN J, PANG X, et al. Stratigraphic architectures and associated unconformities of Pearl River Mouth basin during rifting and lithospheric breakup of the South China Sea[J]. Marine Geophysical Research, 2019, 40(2): 129-144.
[19]	TANG X. Tectonic subsidence of the Zhu 1 Sub-basin in the Pearl River Mouth Basin, northern South China Sea[J]. Frontiers of Earth Science, 2017, 11(4): 729-739.
[20]	WANG P, LI S, SUO Y, et al. Plate tectonic control on the formation and tectonic migration of Cenozoic basins in northern margin of the South China Sea[Z]. [S.l.]: Elsevier Ltd, 2020, 11: 1231-1251.
[21]	钱坤, 闫义, 黄奇瑜. 南海扩张过程及海陆变迁沉积记录[J]. 海洋地质前缘, 2016, 32(8): 10-23.
[22]	李家彪, 丁巍伟, 高金耀. 南海新生代海底扩张的构造演模式: 来自高分辨率地球物理数据的新认识[J]. 地球物理学报, 2011, 54(12): 3004-3015.
[23]	DONG D, ZHANG G, ZHONG K, et al. Tectonic evolution and dynamics of deepwater area of Pearl River Mouth Basin, northern South China Sea[J]. Journal of Earth Science, 2009, 20(1): 147-159.
[24]	李勤英, 罗凤芝, 苗翠芝. 断层活动速率研究方法及应用探讨[J]. 断块油气田, 2000, 7(2): 15-17.
[25]	MCKENZIAE D. Some remarks on the development of sedimentary basins[J]. Earth and Planetary Science Letters, 1978, 40(1): 25-32.
[26]	STECKLER M S, MCKENZIE D. Subsidence of the Atlantic-type continental margin off New York[J]. Earth and Planetary Science Letters, 1978, 41(1): 1-13.
[27]	ZHAO Z, SUN Z, WANG Z, et al. The dynamic mechanism of post-rift accelerated subsidence in Qiongdongnan Basin, northern South China Sea[J]. Marine Geophysical Research, 2013, 34(3): 295-308.
[28]	ALLEN P A, ALLEN J R. Basin Analysis: principles and applications[M]. 3rd ed. Oxford, UK:John Wiley & Sons; Blackwell Scientific Publications, 2013: 349-401.
[29]	KOMINZ M A, BROWNING J V, MILLER K G, et al. Late cretaceous to miocene sea-level estimates from the New Jersey and Delaware coastal plain coreholes: an error analysis[J]. Basin Research, 2008, 20(2): 211-226.
[30]	VAIL P R, MITCHUM R M, THOMPSON S III. Seismic stratigraphy and global changes of sea level: Part 3. Relative changes of sea level from coastal onlap[J]. AAPG Memoir, 1977, 26: 63-81.
[31]	WATT A B. Subsidence and eustasy at the continental margin of eastern North America[M]. 3rd ed. Washington, D C: Maurice Ewing Symposium, 1979: 218-234.
[32]	MA M, LIU C, QI J F. Cenozoic subsidence history of the Pearl River Mouth Basin, northern South China Sea[J]. Research Article, 2018, 55: 750-770
[33]	童亨茂, 聂金英, 孟令箭, 等. 基底先存构造对裂陷盆地断层形成和演化的控制作用规律[J]. 地学前缘, 2009, 16(4): 104-97.
[34]	刘雨晴, 吴智平, 程燕君, 等. 南海北缘古近纪裂陷结构时空差异及控制因素[J]. 中国矿业大学学报, 2019, 48(02): 367-376.
[35]	孙晓猛, 张旭庆, 张功成, 等. 南海北部新生代盆地基底结构及构造属性[J]. 中国科学: 地球科学, 2014, 44(6): 1312-1323.
[36]	鞠东, 刘豪, 姚永坚. 南海北部晚中生代逆冲断裂带厘定与构造转换[J]. 海洋地质前缘, 2015, 31(8): 16-24
[37]	闵慧, 任建业, 高金耀, 等. 南海北部古俯冲带的位置及其对南海扩张的控制[J]. 大地构造与成矿学, 2009, 34(4): 599-605.
[38]	周蒂, 王万银, 庞雄, 等. 地球物理资料所揭示的南海东北部中生代俯冲增生带[J]. 中国科学: 地球科学, 2006, 36(3): 209-218.
[39]	LI F C, SUN Z, YANG H F. Possible spatial distribution of the Mesozoic volcanic arc in the present-day South China Sea continental margin and its tectonic implications[J]. Journal of Geophysical Research, 2017, 123: 6215-6235.
[40]	ZHAO M, QIU X, XIA S, et al. Seismic structure in the northeastern South China Sea: S-wave velocity and v_P/v_S ratios derived from three-component OBS data[J]. Tectonophysics, 2010, 480(1): 183-197.
[41]	李海龙, 吴招才, 许明炬. 南海东北部陆缘地壳结构特征及下地壳高速层成因[J]. 海洋学研究, 2019, 37(2): 44-56.
[42]	WAN K Y, XIA S H, et al. Deep seismic structure of the northeastern South China Sea: origin of a high-velocity layer in the lower crust[J]. Journal of Geophysical Research, 2017, 122: 2831-2858.
[43]	SU D, WHITE N, MCKENZIE D. Extension and subsidence of the Pearl River Mouth Basin, northern South China Sea[J]. Basin Research, 1989, 2(3): 205-222.
[44]	CHEN L, ZHANG Z, SONG H. Weak depth and along-strike variations in stretching from a multi-episodic finite stretching model: evidence for uniform pure-shear extension in the opening of the South China Sea[J]. Journal of Asian Earth Sciences, 2013, 78: 358-370.
[45]	DONG D D, WU S G, LI J B. Tectonic contrast between the conjugate margins of the South China Sea and the implication for the differential extensional model[J]. Earth Sciences, 2013, 57(6): 1415-1426.
[46]	CLIFT P, LIN J. Preferential mantle lithospheric extension under the South China margin[J]. Marine and Petroleum Geology, 2001, 18(8): 929-945.
[47]	CLIFT P, LIN J, BARCKHAUSEN U. Evidence of low flexural rigidity and low viscosity lower continental crust during continental break-up in the South China Sea[J]. Marine and Petroleum Geology, 2002, 19(8): 951-970.
[48]	李海龙, 吴招才, 纪飞, 等. 南海北部地壳密度结构: 基于约束三维重力反演[J]. 地球物理学报, 2020, 63(5): 1894-1912.
[49]	BAI Y, WANG X, DONG D, et al. Symmetry of the South China Sea conjugate margins in a rifting, drifting and collision context[J]. Marine and Petroleum Geology, 2020, 117: 104397.
[50]	张云帆, 孙珍, 庞雄. 珠江口盆地白云凹陷下地壳伸展与陆架坡折的关系[J]. 中国科学: 地球科学, 2014, 44(3): 488-496.
[51]	任建业, 庞雄, 雷超, 等. 被动陆缘洋陆转换带和岩石圈伸展破裂过程分析及其对南海陆缘深水盆地研究的启示[J]. 地学前缘, 2015, 22(1): 102-114. DOI
[52]	DING W, SUN Z, MOHN G, et al. Lateral evolution of the rift-to-drift transition in the South China Sea: evidence from multi-channel seismic data and IODP expeditions 367&368 drilling results[J]. Earth and Planetary Science Letters, 2020, 531: 115932.
[53]	任建业, 庞雄, 于鹏, 等. 南海北部陆缘深水-超深水盆地成因机制分析[J]. 地球物理学报, 2018, 61(12): 4901-4920.
[54]	FRANKE D, SAVVA D, PUBELLIER M, et al. The final rifting evolution in the South China Sea[J]. Marine and Petroleum Geology, 2014, 58: 704-720.
[55]	ZHAO Y, REN J, PANG X, et al. Structural style, formation of low angle normal fault and its controls on the evolution of Baiyun Rift, northern margin of the South China Sea[J]. Marine and Petroleum Geology, 2014, 89: 687-700.
[56]	HUISMANS R, BEAUMONT C. Depth-dependent extension, two-stage breakup and cratonic underplating at rifted margins[J]. Nature, 2011, 473: 74-78.
[57]	ZHANG C, SUN Z, MANATSCHAL G, et al. Syn-rift magmatic characteristics and evolution at a sediment-rich margin: insights from high-resolution seismic data from the South China Sea[J]. Gondwana Research, 2021, 91: 81-96.
[58]	LARSEN H C, MOHN G, NIRRENGARTEN M, et al. Rapid transition from continental breakup to igneous oceanic crust in the South China Sea[J]. Nature Geoscience, 2018, 11(10): 782-789.
[59]	SUN Z, LIN J, QIU N, et al. The role of magmatism in the thinning and breakup of the South China Sea continental margin[J]. National Science Review, 2019, 6(5): 871-876.
[60]	刘安, 武国忠, 吴世敏. 南海东北部下地壳高速层的成因探讨[J]. 地质论评, 2008, 54(5): 609-616.
[61]	孙珍, 李付成, 林间, 等. 被动大陆边缘张-破裂过程与岩浆活动: 南海的归属[J]. 地球科学, 2021, 46(3): 770-789.