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Collaborative Research: Study of Relationship of Crustal Extension to Mantle Dynamics: Paleobotanical Constraints on the Eocene History of Mean Elevations in Pacivic NW

合作研究：地壳伸展与地幔动力学关系的研究：太平洋西北始新世平均海拔历史的古植物学约束

基本信息

批准号：
9725807
负责人：
Peter Molnar
金额：
--
依托单位：
Massachusetts Institute of Technology
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
1998
资助国家：
美国
起止时间：
1998-02-15 至 2001-07-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=9725807&HistoricalAwards=false
关键词：
Collaborative Research Study Relationship Crustal

项目摘要

9725807 Molnar Normal faulting and horizontal crustal extension, not just erosion, ultimately destroy most major mountain belts. Because most such belts have been built by crustal shortening and thickening, some change in the regional geodynamics must occur to cause such a change from horizontal compression to extension. One possibility is that the lower part of the mantle lithosphere, thickened during the phase of compression, becomes unstable and sinks into the mantle beneath the range. When this happens, the range rises, giving it potential energy to drive normal faulting. To test such an idea requires that paleo-altitudes are measured before and after the normal faulting begins. The P.I.s plan to make such measurements using fossil leaf morphology, which has been calibrated to modern climates (and hence altitudes) with an extensive collection of such leaf morphology from modern forests. The Pacific Northwest is an ideal locality for such analysis because the region underwent crustal shortening in Mesozoic time and crustal extension in Cenozoic time and because there are numerous fossil leaf localities, both near sea level and inland where a high mountain belt once lay. ***

小行星9725807 正断层和地壳水平伸展，而不仅仅是侵蚀，最终摧毁了大多数主要的山脉带。由于这类构造带大多是地壳缩短和增厚的产物，因此区域地球动力学的某些变化必然会导致这种由水平挤压向伸展的转变。一种可能性是地幔岩石圈的下部，在压缩阶段增厚，变得不稳定并沉入山脉下方的地幔。当这种情况发生时，幅度上升，给予它驱动正常断层的势能。为了验证这样的想法，需要在正断层开始之前和之后测量古海拔。研究人员计划使用化石叶形态进行此类测量，化石叶形态已被校准到现代气候（以及海拔），并从现代森林中广泛收集了此类叶形态。太平洋西北部是进行这种分析的理想地点，因为该地区在中生代经历了地壳缩短，在新生代经历了地壳伸展，而且在海平面附近和曾经有高山带的内陆都有许多化石叶。 ***