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。大量德干（印度）溢流玄武岩在 K/T 边界喷发，这是与一次重大动物灭绝（例如恐龙）相关的主要地层边界。因此，人们对了解德干火山喷发持续了多长时间以及它对生物进化产生的影响非常感兴趣。传统的测年技术（40Ar/39Ar、K/Ar方法）的不确定度为+/- 0.5 m.y.，因此我们不知道整个喷发持续了几年、100 kyr还是500 kyr！基于晶体生长速率数据的初步计算表明，西高止山脉地区最大量的熔岩包可能在短短 50 凯尔的时间内喷发，这相当于惊人的喷发速率。本项目是一项试点研究，旨在评估一种技术（巨型斜长石斑晶中元素扩散分布随时间的松弛），该技术最终可能为量化单个德干岩浆室活动的持续时间提供一种独立的方法。大型复杂分区斜长石晶体的成分剖面也将用于评估它们作为连续熔岩流中携带的晶体之间的“微观地层”相关性的潜力，以研究岩浆房模型 - 也就是说，连续的熔岩是否从长寿命的动态储层中喷发？经历了多次岩浆侵位、补给、补给和挤压过程。这项工作将需要使用华盛顿州的微钻和激光烧蚀 ICP-MS 进行详细的岩相学和晶体尺寸分布研究，以及单个斑晶中成分区域的高精度微量元素（Mg、Fe、Sr）和 87Sr/86Sr 分布研究佛罗里达国际大学 (FIU) 的大学和电子微探针分析。更广泛的影响。这项研究的一个吸引人的方面是它有可能提供当前同位素和古地磁方法无法实现的时间分辨率。金融情报机构是一个少数派机构。该项目将涉及一名博士生（梅尔罗伊·博尔赫斯）的教育和培训，并可能涉及一名兼职本科生（凯文·周）。拟议的工作将促进美国和印度多个机构的研究人员之间的合作。