西北印度洋卡尔斯伯格脊61°24'E—61°48'E段的构造地貌及岩浆-构造活动性

doi:10.3969/j.issn.1001-909X.2024.04.007

摘要/Abstract

摘要：

洋中脊的地形地貌特征直接受构造运动和岩浆活动控制,对其进行研究可以了解洋中脊的构造演化历史和岩浆作用过程,对于海底矿产资源的勘探具有重要意义。本文利用中国大洋24航次采集的船载多波束声呐数据,用定量分析的方法对西北印度洋卡尔斯伯格脊61°24'E—61°48'E段的地形地貌特征开展研究,计算了岩浆侵入比及断层相关指数,并探讨了研究区的岩浆-构造意义,获得了以下认识:1)研究区可划分为A、B、C、D四个二级洋中脊段,其岩浆-构造活动期间隔分别为0.15、0.50、0.70和0.21 Ma。2)洋中脊A段和B段为不对称扩张段,岩浆贫乏,以构造作用为主,处于构造活动期;洋中脊C段为对称扩张段,岩浆较为充足,以岩浆作用为主,处于轴向火山脊构建期;洋中脊D段为对称扩张段,岩浆贫乏,以构造作用为主,处于构造活动期。3)在洋中脊段两侧断层核密度值高的区域,有可能形成热液活动区,将是未来进一步勘探的目标区域。

关键词: 卡尔斯伯格脊, 地形地貌, 岩浆周期, 定量分析, 岩浆-构造活动, 岩浆侵入比, 不对称扩张, 核密度

Abstract:

The topographic and geomorphologic features of mid-ocean ridges are directly controlled by tectonic movements and magmatic activities, and study of them can help us to understand the tectonic evolution history and magmatic processes of mid-ocean ridges, and is also of great significance to the exploration of deep-sea mineral resources. In this paper, the shipboard multibeam sonar data collected during the China Ocean 24 Cruise were utilize to study the topographic and geomorphologic features of the Carlsberg Ridge in the Northwest Indian Ocean by applying the quantitative analysis method with the 61°24'E-61°48'E segment as the research target, the magma intrusion ratio and the fault correlation index were calculated, and the magma-tectonic significance of the study area was discussed. The study area can be divided into four secondary mid-ocean ridge segments (A, B, C, and D). The active intervals of magma-tectonic periods for segments A, B, C, and D are 0.15, 0.50, 0.70 and 0.21 Ma, respectively. The mid-ocean ridge segments A and B are asymmetric dilatation sections with poor magma and mainly tectonic action, belonging to the period of tectonic activity; the mid-ocean ridge segment C is a symmetric dilatation section with sufficient magma and mainly magmatic action, belonging to the period of axial volcanic ridge construction; the mid-ocean ridge segment D is a symmetric dilatation section with poor magma and mainly tectonic action, belonging to the period of tectonic activity. Faults area with high kernel density on the two flanks of the mid-ocean ridge section has a possibility of forming an area of hydrothermal activity, which is a target area of further exploration.

Key words: Carlsberg Ridge, topography and geomorphology, magma cycles, quantitative analysis, magmatic-tectonic activity, magma intrusion ratio, asymmetric expansion, kernel density

中图分类号:

P736.1

叶盛源, 韩喜球, 李洪林. 西北印度洋卡尔斯伯格脊61°24'E—61°48'E段的构造地貌及岩浆-构造活动性[J]. 海洋学研究, 2024, 42(4): 70-82.

YE Shengyuan, HAN Xiqiu, LI Honglin. The tectonic geomorphology and magmatic-tectonic activity in the 61°24'E-61°48'E segment of the Carlsberg Ridge in the Northwest Indian Ocean[J]. Journal of Marine Sciences, 2024, 42(4): 70-82.

图/表 16

图1 研究区地形图 (水深数据来源于中国大洋24航次;投影方式为高斯-克吕格;地形分辨率为50 m;右上角的小地图为印度洋洋中脊分布图,图中的红线为洋中脊线,黄线为板块边界,红色五角星为研究区位置。)

Fig.1 Topographic map of the study area (The bathymetric data are sourced from the DY24 Cruise. The projection method is Gauss-Kruger. The grid resolution is 50 m. The small globe map in the upper right corner is the distribution map of Indian Ocean ridges, the red line in the map is the mid-ocean ridge line, the yellow line is the plate boundary, and the red five-pointed star is the location of the study area.)

图2 洋中脊剖面参数测量示意图

Fig.2 Diagram of measurement parameters for the profile of the mid-ocean ridge

图3 M值计算取值示意图

Fig.3 Schematic diagram of M value calculation

图4 剖面位置图

Fig.4 Location of cross-sections

图5 4个洋中脊段典型剖面图 (图中黑色虚线代表断层。)

Fig.5 Typical cross-sections of four mid-ocean ridge segments (The black dotted lines in the figure are the faults.)

表1 洋中脊A、B、C和D段的形态和一些重要构造特征参数

Tab.2 Morphology and some important structural feature data of mid-ocean ridge segments A, B, C and D

名称	脊段长度 /km	轴部裂谷宽度/km	最大水深/m	轴部裂谷高度/m	AVR 高度/m	轴部裂谷高宽比/ (×10^-3)
洋中脊A段	14.0		4 075
剖面1		13.6	4 068	900	130	66.2
剖面2		10.3	3 952	801	163	77.8
剖面3		9.5	3 460	683	280	71.9
剖面4		8.9	3 901	860	112	96.6
洋中脊B段	40.0		4 175
剖面5		9.5	4 087	884	405	93.1
剖面6		9.1	4 148	1 313	685	144.3
剖面7		10.4	3 980	1 467	667	141.1
剖面8		9.5	3 556	1 012	528	106.5
剖面9		10.2	3 548	1 004	322	98.4
剖面10		9.8	3 700	1 102	500	112.4
剖面11		9.7	3 972	1 148	580	118.4
剖面12		9.8	3 957	1 617	451	165.0
剖面13		9.4	4 016	1 673	251	178.0
剖面14		8.9	3 947	1 340	220	150.6
洋中脊C段	21.0		4 370
剖面17		16.9	4 343	1 013	306	59.9
剖面18		15.5	4 125	1 092	461	70.5
剖面19		13.8	4 141	1 197	603	86.7
剖面20		14.6	4 087	957	660	65.5
剖面21		13.7	4 028	697	832	50.9
洋中脊D段	17.5		3 920
剖面22		20.9	3 845	1 429	275	68.4
剖面23		20.5	3 782	996	391	48.6
剖面24		15.4	3 648	953	202	61.9
剖面25		14.8	3712	643	258	43.4

图6 洋中脊轴向构造信息图

Fig.6 Informational diagram of mid-ocean ridge axial structure

图7 研究区断层构造图

Fig.7 Fault structure map of the study area

图8 研究区断层长度、数量(a)及平均方位统计图(b)

Fig.8 Fault length, quantity (a) and average azimuth statistical map (b) in the study area

图9 研究区断层核密度图

Fig.9 Fault kernel density map of the study area

图10 研究区火山机构核密度图

Fig.10 Volcanic kernel density map of the study area

图11 洋中脊A段岩浆周期

Fig.11 The magma cycle of the mid-ocean ridge segment A

图12 洋中脊B段岩浆周期

Fig.12 The magma cycle of the mid-ocean ridge segment B

图13 洋中脊C段岩浆周期

Fig.13 The magma cycle of the mid-ocean ridge segment C

图14 洋中脊D段岩浆周期

Fig.14 The magma cycle of the mid-ocean ridge segment D

图15 研究区各洋中脊段轴部裂谷的岩浆构造阶段

Fig.15 The magmatic tectonic stage of the axial rift of the four mid-ocean ridge segments in the study area

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