RUI: Motion History and Tectonic Significance of Major Faults in Southeastern New England

RUI：新英格兰东南部主要断层的运动历史和构造意义

• 批准号: 8708244
• 负责人: Arthur Goldstein
• 金额: $ 4.7万
• 依托单位: Colgate University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1987
• 资助国家: 美国
• 起止时间: 1987-07-01 至 1989-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=8708244&HistoricalAwards=false
• 关键词: RUI; Motion; History; Tectonic; Significance

The goals of this project are to define the thermal history, direction, sense and timing of motion(s) on potential terrane-bounding faults in the northern Appalachians. The regional geology is reasonably well known with the exception of fault motions. The fault system to be studied marks the western boundary of the Avalon zone in southeastern New England and may be a segment of a fault system which spans the northern Appalachians. Although the faults have been proposed as marking a Permian collisional suture, preliminary results suggest that various segments have experience different motion histories. The entire system of faults may have experienced Silurian (430-400 Ma.) left-lateral motion with a thrust component and some segments were reactivated in Permian time as low-angle normal faults. Additional work is required to define the motion histories of fault segments not yet studied, to establish relationships between segments with different motion histories, to investigate possible relationships between fault motion and deformation in isolated occurrences of Pennsylvanian metasedimetary rocks and to integrate these results with the regional geology. Techniques to be used will be standard detailed structural analysis in the field and microstructural analysis on oriented thin sections. Thermal histories will be established by characterization of temperature dependent microstrutures corroborated by phase equilibria where applicable. Timing of motions will be established by structural analysis of dated igneous rocks. Student involvement will take the form of two undergraduate field assistants for each of the two field seasons and several "senior honors theses". Results are expected to help constrain the tectonic history of some of the terranes in New England.

该项目的目标是确定阿巴拉契亚北部潜在的地界断层的热历史、方向、感觉和运动时间。除断层运动外，该地区的地质情况相当为人所知。待研究的断层系统标志着新英格兰东南部阿瓦隆带的西部边界，可能是横跨阿巴拉契亚山脉北部的断层系统的一部分。虽然这些断裂被认为是二叠纪碰撞缝合的标志，但初步结果表明，不同的断层段经历了不同的运动历史。整个断裂系统可能经历了志留纪（430-400 Ma）带逆冲成分的左旋运动，部分断裂段在二叠纪时期被重新激活为低角度正断层。还需要进一步的工作来定义尚未研究的断层段的运动历史，建立具有不同运动历史的断层段之间的关系，研究宾夕法尼亚系变质沉积岩孤立发生的断层运动与变形之间的可能关系，并将这些结果与区域地质相结合。使用的技术将是现场标准的详细结构分析和定向薄片的微观结构分析。热历史将通过表征温度相关的微观结构来建立，并在适用的情况下通过相平衡来证实。运动的时间将通过对年代确定的火成岩的结构分析来确定。学生的参与将采取两名本科生实地助理负责两个实地季节和几篇“高级荣誉论文”的形式。研究结果有望帮助确定新英格兰地区一些地体的构造历史。