当前位置: X-MOL 学术Tectonics › 论文详情
Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)
Locally Derived, Meteoric Fluid Infiltration Was Responsible for Widespread Late Paleozoic Illite Authigenesis in the Appalachian Basin
Tectonics ( IF 4.2 ) Pub Date : 2020-07-20 , DOI: 10.1029/2020tc006137
A. Boles 1 , B. Pluijm 1
Affiliation  

Isotopic and geochronologic investigation of authigenic, K‐bearing clays in the Appalachian Plateau of the northeastern U.S. Midcontinent yields new insights about the tectonic and diagenetic history of the North American sedimentary cover sequence. In situ texture analysis by High Resolution X‐ray Texture Goniometry indicates preservation of bedding‐parallel diagenetic fabrics with burial depths of 2–5 km, and illite mineralization temperatures are spatially variable, ranging from 80 to 190 °C, correlating to similar depths of 3–6 km. The mineralizing geofluid is surface derived, with δD values ranging from −48‰ to −72‰ (in the range of predicted Pangea meteoric fluid). In addition, we find that mineralizing fluid δD values increase away from the orogenic front, consistent with a rain shadow effect from the high elevation Appalachian orogen. The age of authigenic illite is constrained by 40Ar/39Ar geochronology to 308–318 Ma, reflecting Upper Carboniferous diagenesis. We postulate that far‐field stress transmission from continent‐continent collision created regional permeability pathways for surface fluids, altering the hydrologic architecture of the brittle crust and allowing meteoric fluid infiltration into upper crustal rocks. This interpretation challenges the popular view of tectonically forced, lateral fluid flow from the Appalachian orogen (squeegee hypothesis).

中文翻译:

阿巴拉契亚盆地晚古生代伊利特造山作用是由局部衍生的流变流体渗透引起的。

对美国中部东北部阿巴拉契亚高原自生的含钾黏土的同位素和地球年代学研究,对北美沉积覆盖层的构造和成岩史提供了新的见解。通过高分辨率X射线纹理测角仪进行的原位纹理分析表明,埋藏深度为2-3 km的顺层平行成岩织物的保存情况,伊利石矿化温度在空间上可变,范围从80到190°C,与类似的深度相关3–6公里。矿化流体是表面衍生的,δD值在-48‰至-72‰之间(在预测的Pangea陨石范围内)。此外,我们发现矿化流体的δD值远离造山带前缘而增加,这与高海拔阿巴拉契亚造山带的雨影效应一致。40 Ar / 39 Ar年代学到308-318 Ma,反映了上石炭统的成岩作用。我们假设大陆-大陆碰撞的远场应力传递为地表流体创造了区域渗透路径,从而改变了脆性地壳的水文结构,并使陨石流体渗透到上地壳岩石中。这种解释挑战了来自阿巴拉契亚造山带的构造强迫的横向流体流动的流行观点(刮水板假设)。
更新日期:2020-07-20
down
wechat
bug