西南印度洋脊50.5°E火山喷发高地是热点与洋中脊相互作用的产物吗?  

IS THE VOLCANIC ERUPTION HIGH THE PRODUCT OF HOTSPOT AND MID-OCEAN RIDGE INTERACTION?

作　　者：梁裕扬 李家彪[2] 

机构地区：[1]中国科学院海洋研究所,青岛266071 [2]国家海洋局第二海洋研究所海底科学重点实验室,杭州310012 [3]中国科学院大学,北京100049

出　　处：《海洋地质与第四纪地质》2015年第1期71-79,共9页Marine Geology & Quaternary Geology

基　　金：国家自然科学基金重点项目(91028006);国家自然科学基金项目(41176046);国家大洋专项(DYXM-115-02-3-01);大洋"973"项目子课题(2012CB417301)

摘　　要：观察西南印度洋脊(SWIR)27洋段(据Cannat等(1999)洋脊分段及命名)高分辨率多波束资料,发现其50.5°E轴部为一火山喷发高地,总体地形特征似乎类似受热点影响的洋脊。对该段洋脊地形作了详细分析,并结合受热点影响洋脊具有的一般特征,从地形地貌、地球物理场、岩石地球化学等方面分析了该段洋脊受热点影响的可能性。地形上缺少轴外地形表达,两翼也没有不对称现象;岩石地球化学上最普遍分布的仍是正常MORB。再者,在Crozet热点的相对运动历史轨迹上没有留下明显的痕迹,因此,其对相关洋脊产生有效影响的可能性并不大。综合SWIR 27洋段各方面特征,可说明其确实受某种因素影响,导致岩浆通量相比邻近洋段有大幅增加,但这种因素可能不是受热点影响,而是与大西洋中脊(MAR)上三段轴部地形异常的洋脊一样,是产生于由不均一地幔导致的洋脊局部岩浆增加。It is found from the high-resolution multibeam data of Segment 27（Cannat et al.1999）on the Southwest Indian Ridge（SWIR）that there is an unexpected volcanic eruption high along the axis at 50.5E,which is somewhat similar to the ridges effected by hotspots.We compared the high with the general characteristics of hotspot-effected mid-ocean ridges,made detailed topographic analysis and studied the topography,geophysical field and geochemical characteristics of the high in order to define whether the Segment 27 is effected by any hotspot nearby.Generally speaking,although there is some sort of similarities to the hotspot-effected ridge,it is not typical.Topographically,there is no off-axis topographical anomaly or asymmetric flanks,and geochemically,the most commonly distributed rocks are still normal basalts.Furthermore,there is actually no obvious record in the historical track of the Crozet hotspot showing any efficacious impact on SWIR.In this regard,we concluded that the Segment 27 was indeed effected by something which led to a substantial increase in magmatic flux,but most probably not the interaction with Crozet hotspot.A more reasonable interpretation is that this unexpected volcanic eruption high was resulted from a robust magmatism caused by local heterogeneity of mantle,just as the three similar ridge segments of MAR（Middle Atlantic Ridge）mentioned in literatures.

关 键 词：洋中脊—热点 地形地貌地球物理场 地球化学 不均一地幔 

分 类 号：P736.1[天文地球—海洋地质]