Collaborative Research: Storage Duration of Giant Plagioclase Basalts, Deccan Traps, India

合作研究：印度德干圈闭巨型斜长石玄武岩的储存持续时间

• 批准号: 0538012
• 负责人: Gautam Sen
• 金额: --
• 依托单位: Florida International University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-01-01 至 2008-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0538012&HistoricalAwards=false
• 关键词: Collaborative; Research; Storage; Duration; Giant

Intellectual Merit. The bulk of the voluminous Deccan (India) flood basalts erupted at the K/T boundary, a major stratigraphic boundary associated with a major faunal extinction (e.g., the dinosaurs). Hence, there is a great deal of interest in understanding how long the Deccan eruption lasted and what impact it had on biotic evolution. Conventional dating techniques (40Ar/39Ar, K/Ar methods) have an uncertainty of +/- 0.5 m.y., and thus we do not know whether the whole eruption lasted a few years, 100 kyr, or 500 kyr! Preliminary calculations based on crystal growth rate data suggest that the most voluminous lava package from the Western Ghats region could have been erupted in as little as 50 kyr, corresponding to a phenomenal eruption rate. The present project is a pilot study aimed at evaluating a technique (time-dependent relaxation of diffusion profiles of elements across compositional zones in giant plagioclase phenocrysts) that may eventually provide an independent method for quantifying the duration of activities of individual Deccan magma chambers. Compositional profiles across large complexly zoned plagioclase crystals will also be utilized to evaluate their potential as 'micro-stratigraphic' correlations between crystals carried in successive lava flows to investigate magma chamber models - that is, do successive lavas erupt from long-lived dynamic reservoirs that underwent multiple episodes of magma emplacement, recharge, recharge, and extrusion. This work will entail detailed petrographic and crystal-size distribution studies coupled with high precision trace element (Mg, Fe, Sr) and 87Sr/86Sr profiles across compositional zones in individual phenocrysts using microdrill and Laser-ablation ICP-MS at work at Washington State University and electron microprobe analysis at Florida International University (FIU).Broader impacts. An appealing aspect of the proposed study is its potential to deliver time-resolution that is not attainable with current isotopic and paleomagnetic methods. FIU is a minority institution. The project will involve the education and training of a doctoral student (Melroy Borges) and likely will involve one part-time undergraduate (Kevin Chau). The proposed work will promote collaborations between investigators at several institutions in the US and India.

智力优点。大部分大型Deccan（印度）洪水盆地在K/T边界爆发，K/T边界是与主要动物灭绝相关的主要地层边界（例如，恐龙）。因此，了解Deccan爆发持续了多长时间以及它对生物进化的影响有很大的兴趣。常规的约会技术（40AR/39AR，K/AR方法）的不确定性为+/- 0.5 M.Y.，因此我们不知道整个喷发是否持续了几年，100 kyr还是500 kyr！基于晶体生长速率数据的初步计算表明，西高止山脉区域中最大的熔岩包装本来可以爆发到50 kyr中，这对应于惊人的喷发率。本项目是一项试点研究，旨在评估一项技术（巨型斜长石溶质晶体中元素的扩散谱的时间依赖性松弛）最终可能提供一种独立的方法来量化单个Deccan Magma Chambers的活动持续时间。在大型复杂的斜长石晶体上的组成谱也将被用来评估它们的潜力，作为在连续的熔岩流中携带的晶体之间的“微地层学”相关性，以研究岩浆室模型，即，长期寿命的动力学爆发了连续的熔岩爆发。这项工作将需要详细的岩石学和晶体尺寸的分配研究，结合高精度的痕量元素（MG，FE，SR）和87SR/86SR的构图区域的87SR/86SR概况，使用微型晶状体和激光型ICP-MS在华盛顿州立大学和电子大学的工作中使用Micrododrill和Laser-Ablation ICP-MS。拟议的研究的一个吸引人的方面是，它的潜力是提供当前同位素和古磁方法无法实现的时间分辨率。 FIU是少数族裔机构。该项目将涉及博士生（Melroy Borges）的教育和培训，并可能涉及一个兼职本科生（Kevin Chau）。拟议的工作将促进美国和印度几个机构的调查人员之间的合作。