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High Resolution Paleomagnetism and Magnetostratigraphy of Ferrar Volcanic rocks from the Southern Mesa Range (North Victoria Land, Antarctica)

梅萨山脉南部（南极洲北维多利亚地）费拉尔火山岩的高分辨率古地磁学和磁性地层学

基本信息

批准号：
131563479
负责人：
Professor Dr. Valerian Bachtadse
金额：
--
依托单位：
Sektion Geophysik
依托单位国家：
德国
项目类别：
Infrastructure Priority Programmes
财政年份：
2009
资助国家：
德国
起止时间：
2008-12-31 至 2013-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/131563479?language=en
关键词：
Resolution Paleomagnetism Magnetostratigraphy Ferrar Volcanic

项目摘要

Continental Flood Basalts (CFB) such as the Karoo-Ferrar province are interpreted as having been emplaced over continental areas in the order of 10 km and within a relatively short period of time of less than 1m.y. and therefore are often linked to mass extinctions. Whether the Karoo-Ferrar volcanic rocks of early Jurassic age meet the requirement of rapid extrusion has recently been debated and geochronological data suggests a longer duration of the volcanic activity of up to 6 m.y. If this longer period of emplacement is realistic than it becomes questionable whether the end- Plienbachian mass extinction is linked to the Karro-Ferrar CFB at all. Taking into account that the early Jurassic geomagnetic field displays extremely high reversal rates, any volcanic sequence which spans more than 1m.y. should record at least one, but probably more, reversals of the Earth magnetic field. It is therefore planned to study paleomagnetically the Kirkpatrick basalts of Mesa Range, Antarctica, where at least 40 volcanic flows are exposed in the Gair Mesa a sequence of up to 800m in height. Preliminary results of earlier studies suggest that there is a realistic chance to isolate primary magnetizations a notion being supported by the presence of unaltered glass in the ground mass which has been described for these rocks indicates the pristine conditions of these basalts. Our studies will be complemented by the determination of paleointensities. Taking into account that the paleointensity data base for the Mesozoic is extremely small, any contribution towards improvement of data density represents a great step forward to a better understanding geodynamo processes in the past.

大陆洪水玄武岩（CFB），如Karoo-Ferrar省，被解释为在不到1米的相对较短的时间内以10公里的速度放置在大陆地区。因此它们经常与大灭绝联系在一起。早侏罗纪时期的Karoo-Ferrar火山岩是否满足快速挤压的要求最近一直存在争议，地质年代学数据表明，火山活动的持续时间长达6英里。如果这种更长的侵位期是真实的，那么Plienbachian末期的大灭绝是否与Karro-Ferrar CFB有关就变得值得怀疑了。考虑到早侏罗世地磁场显示出极高的反转率，任何跨度超过1米的火山序列。应该至少记录一次，但可能更多，地球磁场的倒转。因此，计划对南极洲梅萨山脉的柯克帕特里克玄武岩进行古地磁研究，在盖尔梅萨，至少有40个火山流暴露在高达800米的序列中。早期研究的初步结果表明，有一个现实的机会来隔离初级磁化——这一概念得到了地面质量中未改变的玻璃的支持，这些玻璃被描述为这些岩石，表明这些玄武岩的原始状态。我们的研究将得到古强度测定的补充。考虑到中生代的古强度数据库非常少，任何对数据密度的改进都是对更好地理解过去地球动力学过程的一大步。