Metal Sources and Mechanisms of Enrichment for Cu-Ni-PGE Mineralization in Fe-Ti-Rich Gabbroic Rocks in the Duluth Complex, Minnesota

德卢斯杂岩的Babbitt Cu-Ti-Ni- PGE矿床的浸染式硫化物矿化发生在富铁和富钛的辉长岩中，这些辉长岩与下伏的弗吉尼亚组变质沉积岩接触较近。为了评估可能的金属来源，计划进行Re- Os和Pb同位素研究。这两种同位素系统将提供直接证据，说明金属的地壳或地幔来源的相对重要性，金属富集的机制将通过追踪伴随分离结晶、地壳同化、岩浆补给和岩浆混合的化学变化来评估。德卢斯的地壳硫的增加被认为是导致富硫化物和贫硫化物的氧化磷灰石岩石之间可能存在连续体差异的主要原因。由于化学上的相似性，计划与魁北克St. Urbain和Labrieville斜长岩杂岩中的富铁-钛-磷岩石进行比较研究。研究结果将有助于我们理解层状侵入体、次火山侵入体和块状斜长岩及其相关岩石的矿化异同。

Disseminated sulfide mineralization at the Babbitt Cu-Ti-Ni- PGE deposit of the Duluth Complex is found within iron-and titanium-rich gabbroic rocks that occur near the contact with metasedimentary rocks of the underlying Virginia Formation. In order to evaluate possible metal sources Re- Os and Pb isotopic studies are planned. These two isotopic systems will provide direct evidence as to the relative importance of crustal or mantle sources of metals Mechanisms of metal-enrichment will be evaluated by tracing chemical variations that accompany fractional crystallization, crustal assimilation, magma recharge, and magma mixing. The addition of crustal sulfur at Duluth is thought to be a prime reason for the differences in what may be a continuum between sulfide-rich and sulfide-poor, oxide- apatite rocks. Because of the chemical similarities a comparative study with Fe-Ti-P-rich rocks from the St. Urbain and Labrieville anorthosite complexes in Quebec is planned. Results will aid our understanding of similarities and differences between mineralization in layered intrusions, subvolcanic intrusives, and massif-type anorthosites and related rocks.