Low-δ18Ο in mississippian los leones granite (46°S). Tectonic implications for the understanding of late paleozoic evolution in patagonia

IF 16.4 1区化学 Q1 CHEMISTRY, MULTIDISCIPLINARY

Accounts of Chemical Research Pub Date : 2024-09-21 DOI:10.1016/j.jsames.2024.105174

P. Rossel , M. Suárez , D. Morata , R. De la Cruz

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Abstract

Los Leones Granite represents a calc-alkaline tonalite-granodiorite tabular stock of ∼3 km² intruded within Paleozoic metasedimentary rocks from the Eastern Andean Metamorphic Complex. Two newly obtained zircon SHRIMP U-Pb ages reveal a Middle Mississippian (340-335 Ma) crystallization age, contrasting with previously accepted K-Ar Pennsylvanian age. Isotopic analysis indicate derivation from a depleted source with minimal influence of continental crust contamination (eHf_(i) ∼14), which experienced hydrothermal alteration at high temperatures (δ¹⁸O ∼4.13). New data coupled with contemporaneous subduction-related rocks in Western Patagonia and Antarctica suggest the existence a broader Lower Carboniferous subduction zone extending at least from Northern Patagonia, to Western Antarctica. On the other hand, isotopic signatures depict a tectono-magmatic framework with a thermal configuration of the margin that was modified by the presence of a local slab tear or the progressive horizontalization of the isotherms as result of the ∼20 myr. of magmatic quiescence in the area.

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密西西比时期洛斯莱昂斯花岗岩（南纬 46°）中的低δ18Ο。构造对了解巴塔哥尼亚晚古生代演化的影响

洛斯莱昂内斯花岗岩是一个面积约为 3 平方公里的钙碱性碳酸盐岩-花岗闪长岩岩体，侵入于东安第斯变质岩群的古生代变质岩中。新获得的两个锆石 SHRIMP U-Pb 年龄显示了中密西西比（340-335 Ma）结晶年龄，与之前公认的 K-Ar 宾夕法尼亚年龄形成对比。同位素分析表明，该矿石来自贫化源，受大陆地壳污染的影响极小（eHf(i) ∼14），在高温下经历了热液蚀变（δ18O ∼4.13）。新的数据以及西巴塔哥尼亚和南极洲与俯冲有关的同期岩石表明，存在一个更广泛的下石炭统俯冲带，至少从北巴塔哥尼亚一直延伸到南极洲西部。另一方面，同位素特征描绘了一个构造-岩浆框架，其边缘的热构造因当地板块撕裂的存在或该地区岩浆静止 20 万年左右导致的等温线逐渐水平化而发生了变化。

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来源期刊

Accounts of Chemical Research 化学-化学综合

CiteScore

31.40

自引率

1.10%

发文量

312

审稿时长

2 months

期刊介绍： Accounts of Chemical Research presents short, concise and critical articles offering easy-to-read overviews of basic research and applications in all areas of chemistry and biochemistry. These short reviews focus on research from the author’s own laboratory and are designed to teach the reader about a research project. In addition, Accounts of Chemical Research publishes commentaries that give an informed opinion on a current research problem. Special Issues online are devoted to a single topic of unusual activity and significance. Accounts of Chemical Research replaces the traditional article abstract with an article "Conspectus." These entries synopsize the research affording the reader a closer look at the content and significance of an article. Through this provision of a more detailed description of the article contents, the Conspectus enhances the article's discoverability by search engines and the exposure for the research.