Geochemistry of Barail sandstone in Champhai, Mizoram: Implications on provenance and weathering history,Journal of Earth System Science

当前位置： X-MOL 学术 › J. Earth Syst. Sci. › 论文详情

Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)

Geochemistry of Barail sandstone in Champhai, Mizoram: Implications on provenance and weathering history
Journal of Earth System Science ( IF 1.9 ) Pub Date : 2021-02-05 , DOI: 10.1007/s12040-020-01515-9
Malsawmtluangkima Hauhnar , Jimmy Lalnunmawia , Orizen M S Dawngliana

Abstract

Mizoram is geologically young comprising entirely of sedimentary rocks. The Oligocene age of Barail group of sedimentary rocks, exposed near the Indo Myanmar mobile belt, i.e., Champhai area, Mizoram have been studied to infer the provenance and paleoweathering history. The significance of the work is that it will uncover and reconstruct origin of Barail sandstone and restore the tectonic and paleoclimatic conditions based on petrography and geochemistry of the sandstone. The geochemical classification based on diagrams of log(SiO₂/Al₂O₃) vs. log(Na₂O/K₂O) and log(SiO₂/Al₂O₃) vs. log(Fe₂O₃/K₂O) of the Barail sandstones indicated that the sandstones belong to litharenite and wacke. The geochemical characteristics of the rock are plotted in various binary and ternary diagrams and selected ratios of elements are interpreted in the light of source rock characteristics. The Chondrite normalised REE pattern show similar pattern to UCC (Taylor and McLennan 1985) with an enrichment of LREE and depletion of HREE. The ratio of Al₂O₃/TiO₂ and the ternary diagram of La–Th–Sc indicate felsic to intermediate source. Similarly, the high LREE/HREE ratios and negative Eu anomaly (La/Lu)_cn, ratios of Eu/Eu*, La/Sc, La/Co, Cr/Th, Th/Sc, Th/Co and Cr/V ratio indicate felsic source. The binary diagram between ratios of Zr/Sc vs. Th/Sc inferred volcanic source. The sediments are also found to be derived from recycled sedimentary rock which is proved by ratios of Zr/Sc and Th/U. The A–CN–K diagram and weathering indices such as CIA, PIA shows moderate to intense weathering in the source area. The investigated Barail sandstones are chemically mature as indicated by the ICV while the ratio of SiO₂/Al₂O₃ indicated moderate sediment maturity.

Research Highlights

The present work focused on provenance and paleao-weathering history of the sedimentary rocks exposed in Champhai District of Mizoram, located in the eastern region of Indo-Myanmar border.
The research is mainly based on petrological and geochemical approaches. The work revealed the systematic nomenclature of the sandstone to sublitharenite and wacke.
The research found out that the detrital grains of the investigated sandstones are derived from active continental areas and the provenances which are cosmopolitan in nature varying from igneous and metamorphic to recycled sedimentary terrains.
The work also inferred intermediate to intense weathering phenomena in the provenance.

中文翻译：

米佐拉姆邦猜邦Barail砂岩的地球化学：对物源和风化历史的影响

摘要

Mizoram在地质上年轻，完全由沉积岩组成。研究了印度印支移动带附近（即Mizoram的Champhai地区）暴露的Barail组沉积岩的渐新世时代，以推断其起源和古气候历史。这项工作的意义在于，它将发现和重建Barail砂岩的成因，并根据岩石学和砂岩的地球化学来恢复其构造和古气候条件。基于log（SiO ₂ / Al ₂ O ₃）vs .的图的地球化学分类。log（Na ₂ O / K ₂ O）和log（SiO ₂ / Al ₂ O ₃）对Barail砂岩的log（Fe ₂ O ₃ / K ₂ O）表明该砂岩属于锂锰矿和瓦克岩。岩石的地球化学特征绘制在各种二元和三元图中，并根据烃源岩的特征解释了元素的选定比例。球粒陨石归一化REE模式显示出与UCC类似的模式（Taylor和McLennan 1985），其中LREE丰富而HREE耗尽。Al ₂ O ₃ / TiO ₂的比例和La–Th–Sc三元图表明是长源到中间源。同样，高LREE / HREE比和负Eu异常（La / Lu）_cn，Eu / Eu *，La / Sc，La / Co，Cr / Th，Th / Sc，Th / Co和Cr / V之比表示长英质来源。Zr / Sc与Th / Sc之比推断的火山源之间的二元图。还发现沉积物来自回收的沉积岩，这可以通过Zr / Sc和Th / U之比来证明。A–CN–K图和CIA，PIA等风化指数显示了源区中度到强烈的风化。如ICV所示，所研究的Barail砂岩是化学成熟的，而SiO ₂ / Al ₂ O ₃的比例则表明沉积物的成熟度适中。