Characterizing Eastern North American Mantle Using Re-Os

本文将研究北美东部的地幔捕虏体和蛇绿岩（保存的大洋岩石圈），以确定从太古代到中生代大西洋裂谷的地幔岩石圈演化。这两个不同的套样品不同的地幔区域，并将返回补充信息的演化大陆岩石圈地幔，对流地幔，导致海洋岩石圈。这项工作的第一个目标是表征一套地幔捕虏体中发现的层状岩脉和金伯利岩在北部纽约，佛蒙特州和魁北克。这些捕虏体包含了从太古代到白垩纪北美东部地幔演化的信息。第二个目标是确定跨越阿巴拉契亚山脉的构造就位蛇绿岩中铬铁矿的Re-Os系统学。这些蛇绿岩都是在奥陶纪的短时间内结晶并侵位的。这个样本集将允许对流地幔的锇同位素的异质性的评价，并俯冲板派生的锇在形成超俯冲带海洋岩石圈的可能作用。本科生研究人员将执行大部分的工作中概述了这个建议作为独立的研究或高级论文项目的一部分。该研究的主要贡献是更好地理解造山运动中岩石圈的形成过程。

MinarikEAR-0229995Mantle xenoliths and ophiolites (preserved oceanic lithosphere) from eastern North America will be studied with the purpose of constraining the evolution of mantle lithosphere from the Archean through the Mesozoic Atlantic rifting. These two different suites sample different mantle regions and will return complementary information on the evolution of the subcontinental lithospheric mantle, and the convecting athenospheric mantle which gives rise to oceanic lithosphere. The first goal of this work is to characterize a set of mantle xenoliths found in lamprophyre dikes and kimberlites in upstate New York, Vermont, and Quebec. These xenoliths hold information about the evolution of the mantle under eastern North America from the Archean to the Cretaceous. The second goal will be to determine the Re-Os systematics of chromites from tectonically emplaced ophiolites spanning the length of the Appalachians. These ophiolites all crystallized and were emplaced within a short period of time during the Ordovician. This sample set will allow an evaluation of the heterogeneity of the convecting mantle with respect to osmium isotopes, and of the possible role of subducting slab-derived osmium during the formation of supra-subduction zone ocean lithosphere.Undergraduate student researchers will perform much of the work outlined in this proposal as part of independent research or senior thesis projects. The major contributions of this study will be a better understanding of the processes of creation of lithosphere during mountain-building events.