Compositional evolution of lava plains in the Syria-Thaumasia Block,Mars  

作　　者：HUANG Jun XIAO Long 

机构地区：[1]Planetary Science Institute,China University of Geosciences [2]Mars Space Flight Facility,Arizona State University

出　　处：《Science China(Physics,Mechanics & Astronomy)》2014年第5期994-1000,共7页中国科学：物理学、力学、天文学（英文版）

基　　金：supported by China Postdoctoral Science Foundation (Grant No. 2013M540614);the Postdoctoral International Exchange Project;the National Natural Science Foundation of China (Grant No. 41373066);the Specialized Research Fund for the Doctoral Program of Higher Education (SRFDP) (Grant No. 20130145130001)

摘　　要：Tharsis is the most prominent volcanic province on Mars,yet the compositions of lava flows and how composition relates to the development of Tharsis are poorly known.Most of Tharsis is covered with air-fall dust,which inhibits spectroscopic determination of lava mineralogy.The Syria-Thaumasia Block(STB)is a complex tectono-volcanic province closely related to the Tharsis bulge.The lava plains of STB have different emplacement ages,which provide an opportunity to examine whether magma composition changed with the evolution of Tharsis.In this study,we assessed the lava plains using Thermal Emission Spectrometer(TES)data.Using derived physical properties,we targeted dust-free regions from four different-aged geological units'surfaces and determined the mineralogical composition by modeling the average TES surface spectrum from each of the four surfaces.All units have similar mineralogy but the younger two units have elevated abundance of high-SiO2phases.The spatial distribution of wrinkle ridges indicates lava plains of unit HNr(older ridged plains material)and Hr(younger ridged plains material)were emplaced before the rise of Tharsis,whereas Hsl(flows of lower member)and Hsu(upper member)were emplaced after Tharsis uplift was initiated.We show that the magma composition differed in the lava plains of STB after the uplift of Tharsis.This study further characterizes early martian magma composition and evolution.Tharsis is the most prominent volcanic province on Mars, yet the compositions of lava flows and how composition relates to the development of Tharsis are poorly known. Most of Tharsis is covered with air-fall dust, which inhibits spectroscopic de- termination of lava mineralogy. The Syria-Thaumasia Block （STB） is a complex tectono-volcanic province closely related to the Tharsis bulge. The lava plains of STB have different emplacement ages, which provide an opportunity to examine whether magma composition changed with the evolution of Tharsis. In this study, we assessed the lava plains using Thermal Emission Spectrometer （TES） data. Using derived physical properties, we targeted dust-free regions from four different-aged geological units＇ surfaces and determined the mineralogical composition by modeling the average TES surface spectrum from each of the four surfaces. All units have similar mineralogy but the younger two units have elevated abundance of high-SiO2 phases. The spatial distribution of wrinkle ridges indicates lava plains of unit HNr （older ridged plains material） and Hr （younger ridged plains material） were emplaced before the rise of Tharsis, whereas Hsl （flows of lower member） and Hsu （upper member） were emplaced after Tharsis uplift was initiated. We show that the magma composition differed in the lava plains of STB after the uplift of Tharsis. This study further characterizes early martian magma composition and evolution.

关 键 词：Syria-Thaumasia Block lava plains volcanism THARSIS MARS 

分 类 号：P185.3[天文地球—天文学]