Petrogenesis of volcanic rocks from Eastern Manus Basin: indications in mineralogy and geochemistry  

作　　者：Xia ZHAO Liyan TIAN Jianhui SUN Peng HUANG Yan LI Yue GAO 

机构地区：[1]CAS Key Laboratory for Experimental Study under Deep-sea Extreme Conditions,Institute of Deep-sea Science and Engineering,Chinese Academy of Sciences,Sanya 572000,China [2]Key Laboratory of Marine Geology and Environment,Institute of Oceanology,Chinese Academy of Sciences,Qingdao 266071,China [3]University of Chinese Academy of Sciences,Beijing 100049,China [4]Center for Ocean Mega-Science,Chinese Academy of Sciences,Qingdao 266071,China [5]Laboratory for Marine Geology,Qingdao National Laboratory for Marine Science and Technology,Qingdao 266061,China

出　　处：《Journal of Oceanology and Limnology》2021年第1期89-109,共21页海洋湖沼学报（英文）

基　　金：Supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(Nos.XDB42020303,XDA11030302);the National Natural Science Foundation of China(No.41576055);the National Basic Research Program of China(973 Program)(No.2013CB429702)。

摘　　要：To understand the petrogenesis and magma evolution history in the Eastern Manus Basin(EMB),geochemistry of pyroxene and plagioclase mineral phenocrysts in basaltic andesites and dacites were reported.The plagioclase-melt thermometry showed that,plagioclase in dacites crystalized in 1027.2–1028.5°C under 3.37–5.08 kbar,whereas in basaltic andesite was 1181.4–1187.0°C under 1.79–4.46 kbar.Pyroxene compositions and invariable La/Sm vs La values of whole rock powders indicate that lavas were erupted in rapid cooling rate and mainly controlled by fractional crystallization(FC).In addition,oscillatory zonings in plagioclase and pyroxene phenocrysts indicated small local perturbations and degassing episodes in the magma chamber.Some high Mg#clinopyroxene antecrysts were found in EMB lavas.The highest Mg#of parental EMB melts is 69,which falls into the range of initial partial melts from upper mantle peridotite source(68–75).In terms of isotopic compositions,the EMB lavas most likely originated from Indian-type MORB mantle which was infl uenced by subduction components.In details,the subduction components are mainly derived from the dehydration of a subducted altered oceanic crust,and the contribution of sediment infl uence is minor.The Pb isotopic compositions and end member modeling further suggest that the source of subduction components is more likely from the Pacifi c Plate instead of the Solomon Plate.

关 键 词：Eastern Manus Basin PLAGIOCLASE PYROXENE whole rock Sr-Nd-Pb isotope magma 

分 类 号：P588.14[天文地球—岩石学] P736[天文地球—地质学]