Topography,structural and exhumation history of the Admiralty Mountains region,northern Victoria Land,Antarctica  

作　　者：Maria Laura Balestrieri Valerio Olivetti Federico Rossetti Cecile Gautheron Silvia Catto Massimiliano Zattin 

机构地区：[1]Istituto di Geoscienze e Georisorse,Consiglio Nazionale delle Ricerche,Sede Secondaria Firenze,via G.La Pira 4,50121,Firenze,Italy [2]Dipartimento di Geoscienze,Universita di Padova,Padova,Italy [3]Dipartimento di Scienze,Universita degli Studi Roma 3,Roma,Italy [4]GEOPS,Univ.Paris Sud,CNRS Universite Paris-Saclay,91405,Orsay,France

出　　处：《Geoscience Frontiers》2020年第5期1841-1858,共18页地学前缘（英文版）

基　　金：carried out in the framework of the research projects PDR2013/AZ2.07(coordinated by F.Rossetti);PNRA16_00263(coordinated by V.Olivetti)funded by PNRA(Italian Research Program in Antarctica)。

摘　　要：The Admiralty Mountains region forms the northern termination of the northern Victoria Land,Antarctica.Few quantitative data are available to reconstruct the Cenozoic morpho-tectonic evolution of this sector of the Antarctic plate,where the Admiralty Mountains region forms the northern termination of the western shoulder of the Mesozoic-Cenozoic West Antarctica Rift System.In this study we combine new low-temperature thermochronological data(apatite fission-track and(U-Th-Sm)/He analyses)with structural and topography analysis.The regional pattern of the fission-track ages shows a general tendency to older ages(80-60 Ma)associated with shortened mean track-lengths in the interior,and younger fission-track ages clustering at 38-26 Ma with long mean track-lengths in the coastal region.Differently from other regions of Victoria Land,the younger ages are found as far as 50-70 km inland.Single grain apatite(U-Th-Sm)/He ages cluster at 50-30 Ma with younger ages in the coastal domain.Topography analysis reveals that the Admiralty Mountains has high local relief,with an area close to the coast,180 km long and 70 km large,having the highest local relief of>2500 m.This coincides with the location of the youngest fission-track ages.The shape of the area with highest local relief matches the shape of a recently detected low velocity zone beneath the northern TAM,indicating that high topography of the Admiralty Mountains region is likely sustained by a mantle thermal anomaly.We used the obtained constraints on the amount of removed crustal section to reconstruct back-eroded profiles and calculate the erosional load in order to test flexural uplift models.We found that our back-eroded profiles are better reproduced by a constant elastic thickness of intermediate values(Te=20-30 km).This suggests that,beneath the Admiralty Mountains,the elastic properties of the lithosphere are different with respect to other TAM sectors,likely due to a stationary Cenozoic upper mantle thermal anomaly in the region.

关 键 词：ANTARCTICA THERMOCHRONOLOGY Transantarctic mountains Rift margin uplift 

分 类 号：P597.3[天文地球—地球化学]