Melt Inclusions in Zircon (and other accessory minerals)

Ear-0001168Bodnar/SinhaZircon(ZrSiO4)是大多数花岗岩类岩石中常见的副矿物。花岗岩类岩石中的锆石晶体通常含有结晶熔体包裹体，这些包裹体在岩浆晶体生长过程中被捕获。锆石通常在30到250微米之间，熔融包裹体在20到120微米之间。初步的常量元素和微量元素分析表明，熔融包裹体保存了岩浆化学成分，并提供了传统块状岩石分析不易获得的信息。熔体包裹体的化学成分将用于评估岩浆从源岩熔融(以产生母岩)到岩浆最终结晶的化学演化。反过来，这些信息将被用来推断岩浆历史和熔体在地壳结晶过程中经历的化学变化。在熔化和结晶过程中，一些元素与形成的结晶矿物有亲和力，而另一些元素与熔体相有亲和力。我们将利用熔体包裹体和共存的锆石化学为各种微量元素提供新的分配数据，这些元素通常用于推断花岗岩的岩石成因。初步结果表明，从难熔矿物中的熔融包裹体获得的分配数据，作为小型天然高压灭菌器，可能优于在短期实验室实验中获得的数据。初步的常量元素和微量元素数据表明，锆石中的熔融包裹体保留了原始的熔体成分。然而，这些成分往往与从块状岩石分析中推断的岩浆成分不一致。协调这一差异将是拟议研究的主要重点。

EAR-0001168Bodnar/SinhaZircon (ZrSiO4) is a common accessory mineral present in most granitoid rocks. Zircon crystals from granitoid rocks often contain crystallized melt inclusions trapped during crystal growth from a magma. The zircons typically range from 30 to 250 um and the melt inclusions range from 20 to 120 um. Preliminary major and trace element analyses suggest that the melt inclusions preserve magma chemistries and provide information not easily attainable by traditional bulk rock analyses. The chemistry of the melt inclusions will be used to assess chemical evolution of magmas from melting of source rocks (to produce parental magmas) to final crystallization of magmas. This information, in turn, will be used to infer magma histories and the chemical changes that a melt undergoes during crystallization in the earth's crust. During melting and crystallization, some elements have an affinity for the crystalline minerals that form, whereas other elements have an affinity for the melt phase. We will use the melt inclusion and co-existing zircon chemistries to provide new partitioning data for various trace elements which are commonly used to infer petrogenesis of grantitoid rocks. Preliminary results indicate that partitioning data obtained from melt inclusions in refractory minerals, acting as miniature natural autoclaves, may be superior to data obtained in during short-duration laboratory experiments. Preliminary major and trace element data suggests that melt inclusions in zircon preserve original melt compositions. However, these compositions often disagree with magma compositions inferred from bulk rock analyses. Reconciliation of this discrepancy will be a main focus of the proposed research.