帕里西维拉海盆岩浆-构造过程及钻探建议  

Magmatism and tectonic evolution of the Parece Vela Basin and the drilling proposal

作　　者：鄢全树 袁龙 石学法 YAN Quanshu;YUAN Long;SHI Xuefa(Key Laboratory of Marine Geology and Metallogeny,First Institute of Oceanography,Ministry of Natural Resources,Qingdao 266061,China;Laboratory for Marine Geology,Qingdao National Laboratory for Marine Science and Technology,Qingdao 266237,China)

机构地区：[1]自然资源部第一海洋研究所海洋地质与成矿作用重点实验室,青岛266061 [2]青岛海洋科学与技术试点国家实验室海洋地质过程与环境功能实验室,青岛266237

出　　处：《海洋地质与第四纪地质》2022年第5期103-109,共7页Marine Geology & Quaternary Geology

基　　金：青岛海洋科学与技术试点国家实验室山东省专项经费项目“俯冲带岩浆活动与构造约束”(2022QNLM050201-3);国家自然科学基金“海底岩石学”(41322036);山东省泰山学者建设工程项目。

摘　　要：揭示位于太平洋板块、欧亚板块与印澳板块之间的菲律宾海板块的地质演化是理解西太平洋沟-弧-盆体系形成演化的重要一环。隶属于菲律宾海板块的帕里西维拉海盆及其北侧的四国海盆,是菲律宾海板块发生第二次扩张的产物,记录了菲律宾海板块生长、太平洋板块西向俯冲消减的过程及弧后扩张的重要信息。基于前人研究成果,综述了帕里西维拉海盆的地质与地球物理特征,并将其分为4个区域:东区、西区、南区及中央裂谷区。其中:(1)东区的沉积物较厚(最厚达3 500 m),地形较为平滑,未能识别出磁异常条带,基底熔岩具有类似于弧后盆地玄武岩的微量元素特征和印度洋型MORB(洋中脊玄武岩)的同位素特征。(2)西区的沉积物较薄,地形较为复杂,可识别出10-5D号磁异常条带,海底熔岩的特点类似于东区。(3)南区地形复杂,海山、裂谷、丘陵等海底组构相间分布,可进一步分为5个次级单元,无磁异常条带,其基底熔岩具有类似于N(正常)-MORB和IAB(岛弧玄武岩)之间的微量元素特征和印度洋型MORB的同位素特征。(4)裂谷区,沉积物较薄,广泛分布了拆离断层和核杂岩,水深较深(最深处超过7 500 m),该区域同时出露有肥沃型橄榄岩和难熔型橄榄岩。最后,本文建议了8个钻孔站位,以解决该海盆尚存的一些有关构造-岩浆过程、深部地幔过程、俯冲带过程及沉积古环境方面的重要的基础科学问题。Studying the geological evolution of the Philippine Sea Plate(PSP) is the key to understand the formation and evolution of the trencharc-basin systems in the West Pacific region.The Parece Vela Basin(PVB) and the Shikuko Basin are formed during the second spreading epoch of the western Pacific back-arc system,during which important information about the growth of the Philippine Sea Plate and westward subduction process of the Pacific Plate beneath the PSP is recorded.In this study,the geological and geophysical characteristics of PVB and subdivided the basin into four sub-units are summarized.In the eastern sub-unit,the sediment is thin and the seafloor topography is complex,and the observed magnetic anomalies range from 10 to 5D.The submarine lavas from the sub-unit have similar trace element characteristics to those of back-arc basin basalts and so in isotope imprint to those of the Indian Ocean type MORB(mid-oceanic ridge basalt).In the western subunit,the sediment is thick(up to 3 500 m),the seafloor topography is smooth,the magnetic anomalies are not recognizable,and the compositions of the submarine lavas of the sub-unit are similar to those of the eastern sub-unit.The southern sub-unit,composed by seamounts,rifts,and hills,exhibits a complex morphology.The magnetic anomalies are not recognizable.The lavas from the sub-unit have transitional trace element characteristics between N(normal)-MORB and IAB(island arc basalt),and isotopic features of the Indian Ocean type MORBs(similar to the eastern and western sub-units’).In the rift sub-unit,the sediment is thin,the seafloor topography is composed of detachment faults and oceanic core complexes,and the water depth of seafloor can reach up to 7 500 m.There occurred some residual fertile peridotite,and refractory peridotite as well.Finally,we proposed 8 possible drilling sites in the PVB in attempt to solve some key scientific issues related to tectonic,magmatic,deep mantle,sedimentation,and subduction processes.

关 键 词：海底扩张 核杂岩 地幔源区性质 俯冲过程 帕里西维拉海盆 

分 类 号：P736.11[天文地球—海洋地质]