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

EAR-0106645普里纳尔金伯利岩是一种岩浆类型，它携带着来自地球深部(地幔)的大多数钻石。这些岩浆一般在地球表面喷发，在发现钻石的地表附近形成管状喉道，通常与另一种称为碳酸盐岩的岩浆类型有关。金伯利岩通常被理解为代表了任何岩浆类型的最大起源深度，因此可以告诉我们一些关于地球内部在一般情况下没有取样的深度的信息。传统上，成因深度被认为约为220公里，但最近在极少数钻石中发现的奇异矿物包裹体表明，在某些情况下，成因要深得多，甚至可能到达核幔边界。关于深度超过200公里的熔化过程的化学实验数据非常稀少。该项目旨在研究模拟地球深处约430公里深处的成分的融化关系。这项研究使用的设备被称为多砧压机，能够复制被认为与这些巨大深度可能的熔化过程有关的温度和压力。目的是确定随着压力的增加熔化的温度和产生的熔体的组成。这些数据将提供量化数据，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缓慢地从极端深度输送到金伯利岩，并由在传统上可接受的约220公里深度产生的金伯利岩进行采样。

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.