Ultradeep Kimberlite/Carbonatite Petrogenesis: Melting of Model Carbonated Lherzolite in the System CaO-MgO-Al2O3-SiO2-CO2 at 7-14 GPa

超深金伯利岩/碳酸岩成岩作用：7-14 GPa 下 CaO-MgO-Al2O3-SiO2-CO2 系统中模型碳化二辉橄榄岩的熔融

• 批准号: 0106645
• 负责人: Dean Presnall
• 金额: $ 36万
• 依托单位: University of Texas at Dallas
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-09-01 至 2006-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0106645&HistoricalAwards=false
• 关键词: Ultradeep; Kimberlite; Carbonatite; Petrogenesis; Melting

EAR-0106645PresnallKimberlite is the magma type that is the carrier of most diamonds from the deep interior (mantle) of the Earth. These magmas generally erupt at the Earth's surface, form a pipe-like throat near the surface where the diamonds are found, and are commonly associated with another magma type called carbonatite. Kimberlites are generally understood to represent the greatest depth of origin of any magma type and therefore tell us something about the Earth's interior at depths not generally sampled. Traditionally, the depth of origin has been thought to be about 220 km., but the recent discovery of exotic mineral inclusions in a very few diamonds indicates an origin much deeper in some cases, possibly even to the core-mantle boundary. Experimental data on the chemistry of melting processes at depths in excess of about 200 km are very sparse. This project is designed to examine melting relations for compositions that model the Earth's deep interior at depths up to about 430 km. The apparatus used for this study is called a multianvil press and is capable of duplicating temperatures and pressures thought to be relevant to possible melting process at these great depths. The purpose is to determine the temperature of melting as pressure increases and the compositions of the melts generated. These data will provide quantitative data that will help resolve the issue of whether melting at these depths is reasonable or if the diamonds are transported slowly from extreme depths by solid-state convective processes in the mantle, to be sampled by kimberlites generated at more traditionally accepted depths of about 220 km.

金伯利岩是一种岩浆类型，是地球内部深处（地幔）大多数钻石的载体。 这些岩浆通常在地球表面喷发，在发现钻石的表面附近形成管状喉道，通常与另一种称为碳酸岩的岩浆类型有关。 金伯利岩通常被认为代表了任何岩浆类型起源的最大深度，因此告诉我们一些关于地球内部的深度，而不是通常采样。 传统上，起源的深度被认为是大约220公里，但最近在极少数钻石中发现的外来矿物包裹体表明，在某些情况下，钻石的起源要深得多，甚至可能到核幔边界。 关于深度超过200公里的熔化过程的化学性质的实验数据非常稀少。 该项目旨在研究模拟深度达约430公里的地球深部内部的成分的熔化关系。 用于这项研究的设备被称为多砧压力机，能够复制温度和压力，这些温度和压力被认为与这些深度处可能的熔化过程有关。 其目的是确定随着压力增加的熔化温度和所产生的熔体的组成。 这些数据将提供定量数据，有助于解决在这些深度熔化是否合理的问题，或者钻石是否通过地幔中的固态对流过程从极深处缓慢迁移，由传统上接受的深度约220公里处产生的金伯利岩取样。