地质测温对特立尼达北部山脉热构造、变质作用和剥露的限制

IF 3.5 2区 地球科学 Q1 GEOLOGY
Ivano Gennaro, John Weber, Alberto Vitale Brovarone, Jeanette Arkle, Xu Chu
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引用次数: 0

摘要

特立尼达北部山脉由中生代被动边缘沉积岩组成,在中新世早期经历了韧性变形和亚绿片岩-绿片岩相变质作用。先前的研究表明,在加勒比海板块和南美板块之间,北部山脉的形成分为两个阶段:中新世,最初的碰撞推动了造山运动,随后的走滑板块运动优先挖掘了西部板块,导致变质热梯度向西增加。然而,这些研究无法确定这种梯度是离散的还是连续的,因此构造模型有待检验。在这项研究中,我们使用了碳质材料的拉曼光谱(RSCM),一种经验地温计,以比以前的研究更高的分辨率约束北部山脉的峰值温度。RSCM温度从东部的337°C±10°C突然增加到丘帕拉点以西的442°C±16°C,在以前的地质测绘活动中推断出了一个范围切割断层(丘帕拉断层)。因此,~100°C的离散热不连续很可能代表丘帕拉断层。我们的RSCM得出的峰值变质温度比以前的估计高50°C到100°C,这需要修改构造模型以考虑更深的埋藏和更大的挖掘。本文确定的变质峰条件,以及根据已发表的热年代学资料推断出的断裂时间,与前人提出的两阶段构造模型一致。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
Geothermometric constraints on the thermal architecture, metamorphism, and exhumation of the Northern Range, Trinidad

The Northern Range of Trinidad is composed of Mesozoic passive margin sedimentary rocks that underwent ductile deformation and subgreenschist- to greenschist-facies metamorphism in the early Miocene. Previous studies suggested a two-stage formation of the Northern Range between the Caribbean and South American plates: an initial collision drove mountain building in the Miocene and subsequent strike-slip plate motion preferentially exhumed the western segment, producing a westward increase in the metamorphic thermal gradient. However, these studies were not able to resolve whether this gradient was discrete or continuous so the tectonic model awaits testing. In this study we use Raman spectroscopy on carbonaceous material (RSCM), an empirical geothermometer, to constrain peak temperatures across the Northern Range with a greater resolution than was available in previous studies. The RSCM temperatures show an abrupt increase from 337°C ± 10°C in the east to 442°C ± 16°C west of Chupara Point, where a range-cutting fault (Chupara Fault) had been inferred in previous geologic mapping campaigns. Thus, the discrete thermal discontinuity of ~100°C very likely represents the Chupara Fault. Our RSCM-derived peak metamorphic temperatures are 50°C to 100°C higher than those from previous estimates, requiring revision of tectonic models to account for deeper burial and greater exhumation. The peak metamorphic conditions determined here, and the deduced timing of faulting from published thermochronological data, are consistent with the two-stage tectonic model proposed in previous studies.

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来源期刊
CiteScore
6.60
自引率
11.80%
发文量
57
审稿时长
6-12 weeks
期刊介绍: The journal, which is published nine times a year, encompasses the entire range of metamorphic studies, from the scale of the individual crystal to that of lithospheric plates, including regional studies of metamorphic terranes, modelling of metamorphic processes, microstructural and deformation studies in relation to metamorphism, geochronology and geochemistry in metamorphic systems, the experimental study of metamorphic reactions, properties of metamorphic minerals and rocks and the economic aspects of metamorphic terranes.
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