Implications of Very Low Electrical Resistivity In The Deep Crust of An Active Thick-Skinned Tectonics In Argentina

阿根廷活跃厚皮构造地壳深处电阻率极低的影响

• 批准号: 9909390
• 负责人: John Booker
• 金额: $ 14.83万
• 依托单位: University of Washington
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-03-01 至 2003-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9909390&HistoricalAwards=false
• 关键词: Implications; Very; Low; Electrical; Resistivity

Booker 9909390 A recent pilot magnetotelluric (MT) experiment near Tucuman across the eastern Andean deformation front concludes that the lower crust is as electrically conductive as under southern Tibet. Common to both areas is the rate of crustal strain. If one can show that high conductivity is an inevitable consequence of high strain rate one would have a powerful tool for probing active deformation of the deep crust. In collaboration with Argentine colleagues, the investigators are proposing to collect and analyze new MT data to (1) Determine whether very conductive lower crust at Tucuman is a local or regional feature. (2) Elucidate the transition from resistive to conductive crust at the deformation front. (3) Investigate the possibility of shallow asthenosphere in the mantle. (4) Compare Tucuman with two distinctly different regions of the eastern Andean deformation: (a) San Juan, where the crustal strain rate is high, but the subducted slab is very flat and there may be no intervening asthenosphere and (b) Cordoba, the most eastern extent of the flat slab, where crustal strain islow, but kinematics suggests there ought to be an asthenospheric wedge.

布克9909390最近在横跨东安第斯形变前缘的图库曼附近进行的一项试点大地电磁(MT)实验得出结论，下地壳的导电性与西藏南部的导电性一样。这两个地区的共同之处是地壳应变的速度。如果能证明高电导率是高应变率的必然结果，就有了探测地壳深部活动变形的有力工具。在与阿根廷同事的合作下，研究人员提议收集和分析新的大地电磁数据，以(1)确定图库曼极具导电性的下地壳是否是当地或区域特征。(2)阐明了形变前沿由阻性地壳向导电地壳的转变。(3)探讨地幔存在浅层软流圈的可能性。(4)将图库曼与东安第斯形变的两个截然不同的区域进行比较：(A)圣胡安，地壳应变速率高，但俯冲板块非常平坦，可能没有软流圈；(B)科尔多瓦，板块最东端，地壳应变较低，但运动学表明，应该存在软流圈楔形区。