MORB-derived amphibolites in the Paleozoic basement of the Aluminé Igneous-Metamorphic Complex,.

IF 1.3 4区地球科学 Q2 GEOLOGY

Geologica Acta Pub Date : 2019-11-08 DOI:10.1344/geologicaacta2019.17.10

I. Urraza, S. Delpino, L. E. Grecco

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引用次数: 1

Abstract

Amphibolites included in the metapelitic sequence and as xenoliths in intrusive magmatic rocks outcropping in the southern sector of the Alumine Igneous-Metamorphic Complex (AIMC), Neuquen, Argentina, are studied in detail in order to determine their origin and their subsequent metamorphic evolution. Field evidence and wholerock geochemistry indicate that these rocks were derived from a Mid-Ocean Ridge Basalt (MORB)-type protolith, and were accreted as tectonic slices into the metapelitic sequence that mainly formed the basal accretionary prism associated with a pre-Andean SW-NE subduction setting. Phase relationships, geochemistry of mineral assemblages and geothermobarometry indicate the presence of at least two metamorphic events (M 1 1.9−3.9kbar, 677−745oC and M 2 6.4kbar, 723oC) framed in a counterclockwise P-T path, comparable to those previously determined for the metapelitic country-rocks and metatroctolites outcropping in the same sector of the AIMC. Based on regional correlations and the agreement in the petrological, geochemical, geochronological and structural characteristics, we suggest that the MORB-derived Norquinco amphibolites and neighboring aluminous metasedimentary basement rocks of the AIMC belong to the eastern prolongation of the Western Series of the Coastal Accretionary Complex of Central Chile in west-central Argentina territory.

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铝质火成岩变质杂岩古生代基底中morb衍生角闪岩。

本文详细研究了阿根廷Neuquen铝质火成岩-变质杂岩(AIMC)南段露头侵入岩浆岩中的角闪岩及其变质演化过程。现场证据和整体岩石地球化学特征表明，这些岩石起源于中洋脊玄武岩(MORB)型原岩，并作为构造片沉积到变质岩序列中，变质岩序列主要形成与前安第斯山脉西南向ne俯冲背景相关的基底增生棱镜。相关系、矿物组合的地球化学特征和地温压特征表明，在逆时针的P-T路径上至少存在两个变质事件(m1 1.9 ~ 3.9kbar, 677 ~ 745oC)和m2 6.4kbar, 723oC)，与之前在AIMC同一区域露头的变质岩和变质岩相类似。基于区域对比和岩石学、地球化学、年代学和构造特征的一致性，我们认为morb衍生的Norquinco角闪岩与邻近的AIMC铝质变质沉积基底岩属于阿根廷中西部智利中部海岸沉积杂岩西系的东延。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Geologica Acta 地学-地质学

CiteScore

2.50

自引率

6.70%

发文量

审稿时长

>12 weeks

期刊介绍： - Relevant conceptual developments in any area of the Earth Sciences. - Studies presenting regional synthesis. - Thematic issues or monographic volumes presenting the results from one or more research groups. - Short papers reflecting interesting results or works in progress. - Contributions and results from Research Projects, Workshops, Symposiums, Congresses and any relevant scientific activity related to Earth Sciences. - Geologica Acta aims to stimulate rapid diffusion of results and efficient exchange of ideas between the widespread communities of Earth Science researchers (with special emphasis on Latinamerica, the Caribbean, Europe, the Mediterranean