西贝加尔湖KALTYGEI角ht麻粒岩的P-T条件、U/Pb和40Ar/39Ar同位素年龄

IF 0.8 Q4 GEOCHEMISTRY & GEOPHYSICS

Geodynamics & Tectonophysics Pub Date : 2021-06-23 DOI:10.5800/gt-2021-12-2-0526

N. Volkova, E. Mikheev, A. Travin, A. Vladimirov, A. Mekhonoshin, V. .. Khlestov

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引用次数: 2

摘要

研究对象为Kaltygei角(西贝加尔湖地区)的变质岩麻粒岩，其诊断矿物组合为超高温(UHT)变质岩(正辉石+硅线石+石英)。基于伪剖面的热气压测量得到了变质温度和压力的峰值(T=950℃，P=~9 kbar)，表明麻粒岩在逆行演化过程中处于近等压冷却(IBC)状态。变质作用的U/Pb锆石年龄估计(~1.87 Ga)支持其他研究人员发表的数据。SHRIMP-II锆石U-Pb测年结果表明，锆石年龄最小为1.94 ~ 1.91 Ga。Kaltygei角麻粒岩中的黑云母和角闪石的40Ar/39Ar同位素年龄接近于西贝加尔湖地区早古生代的吸积-碰撞体系。

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P–T CONDITIONS, U/Pb AND 40Ar/39Ar ISOTOPIC AGES OF UHT GRANULITES FROM CAPE KALTYGEI, WESTERN BAIKAL REGION

The study is focused on metapelitic granulites of Cape Kaltygei (Western Baikal region) that contain a diagnostic mineral assemblage of ultrahigh temperature (UHT) metamorphic rocks (orthopyroxene+sillimanite+quartz). The pseudosection-based thermobarometry yields peak metamorphic temperature and pressure values (T=950 °C, P=~9 kbar) and suggests near-isobaric cooling (IBC) conditions during the retrograde evolution of the granulites. The U/Pb zircon age estimates for metamorphism (~1.87 Ga) support the data published by other researchers. The SHRIMP-II U-Pb dating of zircon cores yields a minimum protolith age of 1.94–1.91 Ga. Biotites and amphiboles from granulites of Cape Kaltygei show the 40Ar/39Ar isotopic ages that are close to the Early Paleozoic accretion-collision system of the Western Baikal region.

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来源期刊

Geodynamics & Tectonophysics GEOCHEMISTRY & GEOPHYSICS-

CiteScore

1.20

自引率

14.30%

发文量

审稿时长

24 weeks

期刊介绍： The purpose of the journal is facilitating awareness of the international scientific community of new data on geodynamics of continental lithosphere in a wide range of geolchronological data, as well as tectonophysics as an integral part of geodynamics, in which physico-mathematical and structural-geological concepts are applied to deal with topical problems of the evolution of structures and processes taking place simultaneously in the lithosphere. Complex geological and geophysical studies of the Earth tectonosphere have been significantly enhanced in the current decade across the world. As a result, a large number of publications are developed based on thorough analyses of paleo- and modern geodynamic processes with reference to results of properly substantiated physical experiments, field data and tectonophysical calculations. Comprehensive research of that type, followed by consolidation and generalization of research results and conclusions, conforms to the start-of-the-art of the Earth’s sciences.