摘要
南海中央次海盆残余扩张脊的深部地震探测对于研究南海的形成演化和动力学机制至关重要.本文借助拉布拉多海残余扩张脊内部结构的研究,获得了扩张脊在扩张期和扩张后形成过程的认识.并从多个方面将拉布拉多海与南海进行对比分析,对残余扩张脊的形成环境和形成机制等得到了一些初步认识:两者同属于慢速扩张,扩张过程中,构造作用占主导地位,岩浆作用次之,扩张脊内部结构具有相似性;海盆扩张时期,两者都发生了洋脊跃迁,指示了重要了构造事件;两者的大陆边缘同属于非火山型不对称被动大陆边缘,海盆扩张初期岩石圈以拉张为主,岩浆活动较弱等.这些认识必将为南海中央次海盆残余扩张脊的内部结构研究以及后期的地质解释提供思路和依据.
The deep seismic surveys over the extinct ridge of central sub-basin of South China Sea(SCS) are critical for understanding the evolution and geodynamic mechanism of SCS.In this article,the interior crustal structure of the extinct ridge in the Labrador Sea was reviewed and compared it with the SCS in several aspects,then the preliminary understandings was obtained about the formation and mechanism of extinct ridges.The results showed that both extinct seas belonged to slow-spreading ridges.their formation processes were controlled primarily by tectonism other than by magmatism,and their crustal structures showed high similarity.Ridge jump occurring in both of Labrador Sea and SCS,indicated significant tectonic events during spreading process.Both seas having nonvolcanic asymmetric continental margins,suggested that the extension of lithosphere played a more important role comparing with magmatic activities in the initial spreading stage.This research should provide important ideas and evidences for future studying of the crustal structures and geological interpretation for the extinct ridge in the central subbasin of SCS.