Petrogenesis and tectonic setting of mafic magmatism within the Laguna Amarga Metamorphic Complex, Andes of Catamarca, Argentina: Insights into the opening of the Cuyania/Precordillera terrane from the Ouachita rift

IF 3.2 2区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Precambrian Research Pub Date : 2024-10-23 DOI:10.1016/j.precamres.2024.107601

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Abstract

Neoproterozoic crystalline basement rocks are exposed as fault-bounded blocks over the high Andes of Catamarca. The crystalline basement is stratigraphically grouped into the unique Laguna Amarga Metamorphic Complex and represents the northern extension of the Cuyania/Precordillera terrane. Tabular bodies of meta-mafic rocks are widespread in the basement interspersed within a thick sequence of meta-sedimentary rocks derived from siliciclastic, calc-silicate, and limestone protoliths. Overall, the geochemical characteristics of meta-mafic rocks are in the compositional range of Normal-Mid Ocean Ridge Basalt (Normal-MORB), reflecting a common depleted-mantle source with varying degrees of partial melting. While preserving the typical bulk chemistry of MORB magmatism, some mafic magma underwent differentiation at emplacement, leading to the development of high-Ti mafic rocks. New U-Pb zircon geochronology reveals three distinct age peaks, with two coinciding with ages identified in the metasedimentary host rocks. The dominant Mesoproterozoic age cluster is linked to inherited zircon crystals assimilated within a single meta-mafic rock. In contrast, zircon ages from the late Ordovician to early Devonian are attributed to metamorphic overgrowths. Notably, the third age cluster, delineates a Late Neoproterozoic magmatic event, indicating the temporal span of mafic magmatism. The finding agrees with the best available age (576 ± 17 Ma) for mafic magmatism on the Precordillera Mafic-Ultramafic Belt. Stratigraphic relationships and geochemical fingerprints enable correlation among the meta-mafic rocks from Laguna Amarga, tracing a belt of mafic magmatism with an oceanic affinity that extends southward. Building upon previous works, this study reaffirms that the rift-drift transition of the Cuyania/Precordillera terrane, linked to the Ouachita rift opening from southeastern Grenville, evolved during the latest Neoproterozoic.

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阿根廷卡塔马卡安第斯山脉拉古纳阿马尔加变质岩群内钙质岩浆作用的成岩学和构造背景：从瓦奇塔断裂揭示库亚尼亚/普罗科迪勒拉地层的开辟过程

在卡塔马卡的安第斯高原上，新近新生代结晶基底岩石以断层块的形式出露。结晶基底岩按地层划分为独特的拉古纳-阿玛加变质岩群，是库亚尼亚/普雷科迪莱拉地层的北部延伸。基底中广泛分布着元杂岩的片状岩体，穿插在由硅质碎屑岩、钙硅酸盐岩和石灰岩原岩形成的元沉积岩厚层中。总体而言，元杂岩的地球化学特征与正常-中洋脊玄武岩（Normal-MORB）的成分范围一致，反映了具有不同程度部分熔融的共同贫化幔源。在保留了MORB岩浆岩典型的块体化学成分的同时，一些岩浆岩在成岩过程中发生了分异，从而形成了高钛岩浆岩。新的U-Pb锆石地质年代学显示了三个不同的年龄峰值，其中两个与在变质岩主岩中发现的年龄相吻合。占主导地位的中新生代年龄群与同化在单一元杂岩中的继承锆石晶体有关。相比之下，奥陶纪晚期到泥盆纪早期的锆石年龄则归因于变质过度生长。值得注意的是，第三个年龄群划定了新近纪晚期的岩浆活动，表明了岩浆活动的时间跨度。这一发现与前山地岩浆-超微岩浆带岩浆活动的最佳年龄（576 ± 17 Ma）相吻合。通过地层关系和地球化学指纹，可以对阿玛尔加湖的元黑云母岩进行关联，追踪出一条向南延伸的与大洋亲缘的岩浆岩带。在前人研究的基础上，这项研究再次证实了库亚尼亚/普罗科迪勒拉地层的裂谷-漂移过渡与格勒维尔东南部的瓦奇塔裂谷开口有关，是在新近纪演化的。

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来源期刊

Precambrian Research 地学-地球科学综合

CiteScore

7.20

自引率

28.90%

发文量

325

审稿时长

12 months

期刊介绍： Precambrian Research publishes studies on all aspects of the early stages of the composition, structure and evolution of the Earth and its planetary neighbours. With a focus on process-oriented and comparative studies, it covers, but is not restricted to, subjects such as: (1) Chemical, biological, biochemical and cosmochemical evolution; the origin of life; the evolution of the oceans and atmosphere; the early fossil record; palaeobiology; (2) Geochronology and isotope and elemental geochemistry; (3) Precambrian mineral deposits; (4) Geophysical aspects of the early Earth and Precambrian terrains; (5) Nature, formation and evolution of the Precambrian lithosphere and mantle including magmatic, depositional, metamorphic and tectonic processes. In addition, the editors particularly welcome integrated process-oriented studies that involve a combination of the above fields and comparative studies that demonstrate the effect of Precambrian evolution on Phanerozoic earth system processes. Regional and localised studies of Precambrian phenomena are considered appropriate only when the detail and quality allow illustration of a wider process, or when significant gaps in basic knowledge of a particular area can be filled.