Petrographical and mineral chemistry evidence to delineate the source/sources of the Central Indian Ocean Basin pumices  

作　　者：Niyati G.Kalangutkar Sridhar D.Iyer 

机构地区：[1]School of Earth,Ocean and Atmospheric Sciences,Goa University,Taleigao Plateau,Goa 403206,India [2]Formerly with CSIR-National Institute of Oceanography,Dona Paula,Goa 403004,India

出　　处：《Acta Oceanologica Sinica》2023年第5期102-116,共15页海洋学报（英文版）

基　　金：Part of the research was supported under Endeavour Fellowship awarded to Niyati G.Kalangutkar by Government of Australia and the work was conducted at Queensland University of Technology Laboratory, Brisbane, Queensland

摘　　要：We present data pertaining to mineral assemblages and composition of the Central Indian Ocean Basin(CIOB)pumices.Eight groups of pumices were identified considering the presence of phenocrysts of plagioclase,clinopyroxene,orthopyroxene,hornblende and biotite together with the occurrence of quartz and glass.Pigeonite,fayalite and ulvospinelare reported for the first time from these pumices.In the eight groups,the modal percentage of the constituents are phenocrysts 3%to 19%(avg 9.6%),silicic glass 33%to 54%(avg 43%)and the rest is vesicles.Based on the above factors we have identified the possible sources of the CIOB pumices.The mineral compositions of plagioclase,pyroxenes,and biotite of the CIOB pumices were compared with those of Krakatau and Toba.Most of the plagioclase and pyroxene compositions resemble the Haranggoal Dacite Tuff of Toba and Krakatau.Considering the mineral assemblages and compositions,there are pumices which do not correlate to any of the above eruptions and are probably from yet unidentified source/sources.These sources could either be from nearby terrestrial volcanoes or intraplate seamounts present in the CIOB.In a global context,it is viable that petrological characteristics could be used as initial criteria to determine the source of pumices that occur at abyssal depths in the world ocean.

关 键 词：CIOB PUMICE PETROGRAPHY mineral chemistry Indonesian Arc intraplate volcanism 

分 类 号：P736[天文地球—海洋地质]