Evidence of Paleoproterozoic metamorphism in Vestfold Hills, East Antarctica: Insights from phase equilibria modelling and monazite CHIME dating

IF 1.5 4区地球科学 Q3 ECOLOGY

Polar Science Pub Date : 2023-12-01 DOI:10.1016/j.polar.2023.101004

Aditya Naik , Devsamridhi Arora , Mayuri Pandey , Naresh Chandra Pant , Rashmi Gupta

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Abstract

The Vestfold Hills sector on the coastal fringe of the Princess Elizabeth Land forms part of an Archean to Paleoproterozoic aged cratonic nucleus of the East Antarctic Shield. A charnockite-granite association from the Mossel Gneiss Group in the northern region of the Vestfold Hills is investigated in this work to characterise the metamorphic-magmatic evolution of the area. Conventional thermometry and phase equilibria modelling indicate that the charnockite formed as a result of ultra-high temperature metamorphism at low-intermediate pressure (∼4 kbar). Phase equilibria modelling, reveals that the melt-integrated charnockite composition is a restitic product of a protolith of quartz diorite composition which underwent isobaric heating (peak temperature up to 960 °C) at 4 kbar pressure followed by anatexis. The anatexis of the quartz diorite protolith also resulted in the formation of the associated granitic melt. U–Th-Pb_Total ages obtained from monazites of the granite integrated with CHIME ages extracted using the isochron method indicate an emplacement age of ∼2200 Ma and two younger events are recorded at ∼2000 Ma and ∼1700 Ma. The younger ages are ascribed to the resetting during the emplacement of younger basalt dykes that cross cut the charnockite-granite sequence. Vestfold Hills’ geological correlations with Indian and Australian cratons are discussed considering this new data.

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南极洲东部维斯特福尔丘陵古新生代变质作用的证据：相平衡模型和独居石CHIME年代测定的启示

伊丽莎白公主地沿海边缘的维斯特福尔德丘陵区是南极东盾构的阿新世至古新生代板块地核的一部分。这项研究调查了维斯特福尔丘陵北部地区莫塞尔片麻岩组的黑云母-花岗岩关联，以确定该地区变质-岩浆演化的特征。传统的测温和相平衡模型表明，芒硝是在中低压（4 千巴）下超高温变质形成的。相平衡模型显示，熔融整合的霞石成分是石英闪长岩成分的原岩在 4 千巴压力下经历等压加热（峰值温度高达 960 ℃）后发生消长作用的重结晶产物。石英闪长岩原岩的消长也导致了相关花岗岩熔体的形成。从花岗岩独居石中获得的铀-钍-铅-总年龄与利用等时线法提取的CHIME年龄相整合，表明其成岩年龄为2200Ma∼，两个较年轻的成岩年龄分别为2000Ma∼和1700Ma∼。较年轻的年龄是由于较年轻的玄武岩堤在横切芒硝-花岗岩序列的过程中发生了重置。根据这些新数据，讨论了维斯特福尔德丘陵与印度和澳大利亚火山口的地质关联。

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来源期刊

Polar Science ECOLOGY-GEOSCIENCES, MULTIDISCIPLINARY

CiteScore

3.90

自引率

5.60%

发文量

期刊介绍： Polar Science is an international, peer-reviewed quarterly journal. It is dedicated to publishing original research articles for sciences relating to the polar regions of the Earth and other planets. Polar Science aims to cover 15 disciplines which are listed below; they cover most aspects of physical sciences, geosciences and life sciences, together with engineering and social sciences. Articles should attract the interest of broad polar science communities, and not be limited to the interests of those who work under specific research subjects. Polar Science also has an Open Archive whereby published articles are made freely available from ScienceDirect after an embargo period of 24 months from the date of publication. - Space and upper atmosphere physics - Atmospheric science/climatology - Glaciology - Oceanography/sea ice studies - Geology/petrology - Solid earth geophysics/seismology - Marine Earth science - Geomorphology/Cenozoic-Quaternary geology - Meteoritics - Terrestrial biology - Marine biology - Animal ecology - Environment - Polar Engineering - Humanities and social sciences.