Collaborative Research: Magmatic Evolution of the Midcontinent Rift System: Constraints From the Layered and Felsic Series of the Duluth Complex

9903266 Vervoort本项目的目的是限制中大陆裂谷系（MRS）的岩浆和化学演化。 我们将通过对明尼苏达州东北部MRS的杜鲁和比弗湾侵入杂岩的两个重要组成部分进行综合的主元素和微量元素、Sm-Nd和Lu-Hf同位素以及U-Pb年代学检查来实现这一目标：（1）层状镁铁质侵入体;（2）侵入杂岩上层的大型花岗斑岩（浅成花岗岩）体。MRS裂谷的这一部分对于详细研究至关重要，因为：（1）整个上地壳的大部分区域，包括完整的火山序列和浅岩浆房，都暴露出来，这将使我们能够研究侵入和喷出单元之间的成因关系;（2）该区域包含大量的长英质单元，这些单元在火山序列和侵入杂岩中都具有重要的体积。 这些长英质单位的起源和时间仍然没有完全理解，这将是本提案的主要焦点。对层状镁铁质和花岗斑岩侵入体的岩石成因、演化和年龄的限制将有助于完善中大陆裂谷系统演化的综合模型。

9903266VervoortThe aim of this project is to constrain the magmatic and chemicalevolution of the Midcontinent Rift System (MRS). We will accomplish thiswith an integrated major- and trace-element, Sm-Nd and Lu-Hf isotopic, andU-Pb geochronological examination of two important components of the Duluthand Beaver Bay intrusive complexes of the MRS in northeast Minnesota: (1)layered mafic intrusions; and (2) large granophyric (hypabyssal granitic)bodies that have been intruded into the upper levels of the complexes. This portion of the MRS rift is critical for detailed study because (1)much of the entire upper crustal section, including complete volcanicsequences and shallow magma chambers, is exposed which will allow us toexamine the genetic relationships between the intrusive and extrusiveunits; and (2) this region contains numerous felsic units that arevolumetrically important in both the volcanic sequences and in theintrusive complexes. The genesis and timing of these felsic units is stillnot completely understood and will be a major focus of this proposal. Constraints on the petrogenesis, evolution, and ages of the layered maficand granophyric intrusions will help refine an integrated model for theevolution of the Midcontinent Rift System.