Melting and Volatile Interactions in the 50-70 Kbar Mantle

少量的挥发性分子H2O和CO2 发现 来自地球上地幔的岩浆和岩石 这些挥发物 可能对一些问题产生重要影响， 岩浆，地幔的熔化温度作为一个函数， 深度，熔体的存在沿着地热在原始 地幔和地幔的化学分异。 在过去30年中完成的实验研究集中在 在高达35 kbar的压力下回答这些问题， 只进入最上层的地幔 上层压力很大程度上 由设备限制决定。在过去的三年里，A 集中在70-250千巴压力范围内的活动爆发， 由于多砧高压的出现， 设备. 金伯利岩角砾岩中发现的上地幔岩石碎片 记录化石地热（温度剖面）与拐点 在压力下的压力-温度轨迹（变化） 大约50 kbar。 最深处的样本记录了60 kbar。 在这些石榴石橄榄岩碎片和 金伯利岩表明压力稍高。 的 在地热拐点表明，主要的过程发生在 这个压力范围。 提出的问题，将调查的相互作用， 在50-70千巴压力范围内， 为： * 哪些H2O储层矿物是稳定的，它们是否具有 所需的成分，如钾？ * CO2对岩浆成分有什么影响？ * 压力对三价铁/二价铁比率的影响是什么 在岩浆中？ * H2O-CO2-oxygen与一次反应的关系是什么？ 岩浆成分 一种新研制的装置--主动环带活塞缸 常规操作范围为70 kbar，将用于 探索这些问题。

Small quantities of the volatile molecules H2O and CO2 are found magmas and rocks from the Earth's upper mantle. These volatiles can have important effects on such problems as the origin of magmas, the melting temperature of the mantle as a function of depth, the existence of melts along geotherms in the primitive mantle, and the chemical differentiation of the mantle. Experimental research completed in the past 30 years has focused on answering these questions at pressures up to 35 kbar, reaching only into the uppermost mantle. The upper pressure was largely determined by apparatus limitations. In the last three years, a burst of activity focusing on the 70-250 kbar pressure range has occurred due to the advent of the multiple anvil high pressure device. Fragments of upper mantle rocks found in kimberlite breccias record fossil geotherms (temperature profiles) with an inflection (change) in their pressure-temperature trajectories at pressure of about 50 kbar. The deepest samples record pressures of 60 kbar. Diamonds found in these garnet peridotite fragments and in the kimberlites suggest somewhat higher pressures. The inflection in the geotherm suggests that major processes occur in this pressure range. The proposed problems that will investigate the interaction of volatiles with minerals and magmas at a 50-70 kbar pressure range are: *Which H2O reservoir minerals are stable, and do they have a required constituent such as potassium? *What is the effect of CO2 on magma compositions? *What is the effect of pressure on the ferric/ferrous iron ratio in magmas? *What is the relationship between H2O-CO2-oxygen and primary magma composition? A newly developed apparatus, an active girdle piston-cylinder with a routine operating range to 70 kbar, will be used to explore these questions.