Late Paleozoic Deformation of Interior North America: The Greater Ancestral Rocky Mountains
Late Paleozoic Deformation of Interior North America: The Greater Ancestral Rocky Mountains
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DOI：
10.1306/64ed9a4c-1724-11d7-8645000102c1865d
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发表时间：
1996-09
期刊：
影响因子：
3.5
通讯作者：
Hongzhuan Ye;L. Royden;C. Burchfiel;Martin Schuepbach
中科院分区：
文献类型：
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作者：
Hongzhuan Ye;L. Royden;C. Burchfiel;Martin Schuepbach
北美内陆晚古生代的变形产生了一系列从北西北到西北走向的细长盆地，覆盖了俄克拉何马州、德克萨斯州、新墨西哥州、科罗拉多州和犹他州的大部分地区。每个盆地向相邻的同时期基底隆起区域不对称增厚，由同沉积断裂分隔，具有较大的垂向起伏。整个晚古生代变形区域在时间、几何形状和明显的构造样式上的显著重合，强烈表明这些盆地沉降和基底隆升的对偶区域形成了一个统一的区域变形系统，即大祖先落基山脉。在该地区，盆地沉降和基底隆起几乎是同步的，从切斯特-莫罗万期开始，延续到宾夕法尼亚期，结束于狼坎期（尽管局部发生了狼坎期后的轻微变形）。基底隆升显示了宾夕法尼亚和早二叠世褶皱和断裂的证据。逆断层和逆冲断层已经在许多隆起上钻探，但只有在阿纳达科地区，基底隆起对邻近盆地的逆冲作用被清楚地记录下来。在特拉华盆地和米德兰盆地的边缘也发生了广泛的基底冲断作用，这表明整个更大的祖先落基山脉地区可能是东北-西南方向的板内缩短的结果。大祖先落基山脉内的变形与晚古生代沿北美板块边缘的俯冲同时发生，传统上与瓦希塔-马拉松造山带内逆冲片的侵位有关。沿着瓦希塔-马拉松带的事件的性质、时间和方向使得很难通过瓦希塔-马拉松带沿北美南缘的就位来驱动更大的祖先落基山脉的变形。我们推测变形是由晚古生代安第斯山脉沿北美西南边缘的事件所驱动的。以前未被认识到的安第斯边缘存在的证据来自墨西哥中东部，宾夕法尼亚和二叠纪火山弧表明，向东北倾斜的俯冲边界位于南部和西部。对整个大祖先落基山脉的变形的解释是，在平缓至中等倾斜的逆冲断层上发生了基底相关的逆冲作用，这表明晶体逆冲片下的潜在油气储量可能比通常认为的要大得多。
Late Paleozoic deformation within interior North America has produced a series of north-northwest- to northwest-trending elongate basins that cover much of Oklahoma, Texas, New Mexico, Colorado, and Utah. Each basin thickens asymmetrically toward an adjacent region of coeval basement uplift from which it is separated by synsedimentary faults with great vertical relief. The remarkable coincidence in timing, geometry, and apparent structural style throughout the region of late Paleozoic deformation strongly suggests that these paired regions of basin subsidence and basement uplift form a unified system of regional deformation, the greater Ancestral Rocky Mountains. Over this region, basin subsidence and basement uplift were approximately synchronous, beginning in the Chesterian-Morrowan, continuing through the Pennsylvanian, and ending in the Wolfcampian (although minor post-Wolfcampian deformation occurs locally). The basement uplifts show evidence for folding and faulting in the Pennsylvanian and Early Permian. Reverse faults and thrust faults have been drilled over many of the uplifts, but only in the Anadarko region has thrusting of the basement uplifts over the adjacent basin been clearly documented. Extensive basement-involved thrusting also occurs along the margins of the Delaware and Midland basins, and suggests that the entire greater Ancestral Rocky Mountains region probably formed as the result of northeast-southwest-directed-intraplate shortening. Deformation within the greater Ancestral Rocky Mountains was coeval with late Paleozoic subduction along much of the North American plate margin, and has traditionally been related to emplacement of thrust sheets within the Ouachita-Marathon orogenic belt. The nature, timing, and orientation of events along the Ouachita-Marathon belt make it difficult to drive the deformation of the greater Ancestral Rocky Mountains by emplacement of the Ouachita-Marathon belt along the southern margin of North America. We speculate the deformation was driven instead by events within a late Paleozoic Andean margin along the southwestern margin of North America. Evidence for the existence of this previously unrecognized Andean margin comes from east-central Mexico, where a Pennsylvanian and Permian volcanic arc indicates that a northeast-dipping subduction boundary lay to the south and west. The interpretation that deformation throughout the greater Ancestral Rocky Mountains occurs by basement-involved overthrusting on gently to moderately dipping thrust faults suggests that potential hydrocarbon reserves beneath crystalline thrust sheets may be much greater than is generally supposed.