Petrology and geochemistry of greywackes from the Aravalli Supergroup, Rajasthan, India and the tectonic evolution of a Proterozoic sedimentary basin
Petrology and geochemistry of greywackes from the Aravalli Supergroup, Rajasthan, India and the tectonic evolution of a Proterozoic sedimentary basin
复制标题
DOI：
10.1016/0301-9268(94)90003-5
复制
发表时间：
1994-03
影响因子：
3.8
通讯作者：
D. Banerjee;Prosun Bhattacharya
中科院分区：
文献类型：
--
作者：
D. Banerjee;Prosun Bhattacharya
印度西部拉贾斯坦邦中南部的元古界Aravalli超群主要由粗糙、低品位的变质砂岩、碳酸盐、灰岩、夹层细粉砂质砂岩和变质岩类组成，它们位于太古代的片麻岩、片岩和高级变质岩的基底杂岩上。我们在灰瓦克岩套中划分出四种岩相(A、B、C和D)，每一种岩相都具有特征的QFL组成、粒度和主要、微量和稀土元素的浓度。每种相类型的构造背景只能用QmFLtd.图解来区分。A相和D相灰岩来自再旋回造山带，B相来自与弧有关的安山质烃源岩。C相粉砂质砂岩具有陆块物源，这种岩相解释与基于岩相和沉积结构分析的环境重建具有较好的一致性。唯一的例外是B相，从岩相分析推断的安山型亲缘关系在其露头不能被证明。通过基于常量、微量和稀土元素的构造背景解释，对这些物源判别进行了检验。地球化学数据大体上证实了基于岩石学属性的构造解释。这些以实验室为基础的方法与原始沉积构造的野外测量相结合，使我们能够相当准确地区分物源和构造环境。提出了向西俯冲的元古界板块模式，解释了阿拉瓦利超群的沉积学变化。
The Proterozoic Aravalli Supergroup in south-central Rajasthan, western India is predominantly composed of coarse, low-grade meta-arenites, carbonates, greywackes, interbedded fine-grained silty arenites and metapelites resting on an Archaean basement complex of gneisses, schists and high-grade metasediments. We have differentiated four lithofacies (A, B, C and D) within the greywacke suite, each with characteristic QFL composition, grain size and major, trace and rare earth element concentrations. Tectonic setting for each facies type could only be discriminated using QmFLtplots. Greywackes of facies A and D were derived from a recycled orogen and facies B was derived from arc-related andesitic source rocks. A continental block provenance is indicated for the silty arenites of facies C. This petrofacies-based interpretation shows good agreement with environmental reconstructions based on lithofacies and sedimentary structure analyses. The only exception is facies B, whose andesitic parentage as deduced from petrofacies analysis could not be demonstrated at its outcrop. These provenance discriminations were tested through tectonic setting interpretations based on major, trace and rare earth elements. The geochemical data broadly confirmed the tectonic interpretations made on the basis of the petrological attributes. Use of these laboratory-based methods in conjunction with field measurements of primary sedimentary structures allow us to discriminate provenance and tectonic setting fairly precisely. A Proterozoic plate model with subduction to the west has been proposed to explain the sedimentological variation in the Aravalli Supergroup.