The Appalachian Mountain belt extends through the eastern United States and into southeastern Canada, and is expressed as elongated topographic ridges and valleys of folded and thrust faulted sedimentary and crystalline rock. The Appalachian Plateau (AP) in northwest Pennsylvania, and the Appalachian Valley and Ridge in southeastern Pennsylvania have pronounced differences in geologic structure and topographic expression. The AP consists of gentle folds and low relief (but higher elevation) topography, and 10-15 percent layer parallel shortening (LPS) in rocks sampled at the surface. In contrast, the Valley and Ridge province is a blind fold and thrust belt. The duplexing sequence in the Valley and Ridge is bound by a deep decollement surface within shales of the Cambrian Waynesboro Formation, underlying a detachment at the base of the Ordovician Reedsville shale. Twenty-four kilometers of shortening in the Cambrian – Ordovician sequence is expressed as LPS in the AP. Due to the deficiency of geophysical and outcrop data, all the strata in the AP above the Silurian salt detachment has been assumed to be shortening via LPS plus very gentle folding. Increased hydrocarbon exploration has led to the acquisition of new high quality 3-D seismic and well log data which reveal that the strata from Silurian Salina Group through the Devonian Marcellus shale is shortening through a variety of mechanisms including wedge-style thrust faulting and folding. Through kinematically restored and balanced cross sections we show that the magnitude of microscale shortening calculated from the rocks exposed at the surface of the AP is equal to the magnitude of macroscale shortening in the Silurian-lower Devonian units immediately above the salt detachment. Comparing our interpretations with previously published seismic throughout the AP allows us to extend our model of how shortening in the Salina Group through Marcellus shale is balanced by LPS in the rocks above the Marcellus shale to include the extent of the previously published studies. As the hydrocarbon-rich Marcellus shale is a part of this uniquely deforming Silurian-Devonian package, understanding the geometries of these structures has a potential impact on the quality and quantity of hydrocarbon recovery.

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记录阿勒格尼阵线缩短的几何形状和幅度：美国宾夕法尼亚州莱康明县

阿巴拉契亚山脉带穿过美国东部并进入加拿大东南部，表现为褶皱和逆冲断层沉积岩和结晶岩的拉长地形山脊和山谷。宾夕法尼亚州西北部的阿巴拉契亚高原（AP）与宾夕法尼亚州东南部的阿巴拉契亚山谷和山脊在地质结构和地形表现上存在明显差异。AP 包括平缓的褶皱和低起伏（但海拔较高）的地形，以及在地表采样的岩石中 10-15% 的层平行缩短 (LPS)。相比之下，山谷和山脊省是一个盲褶皱和逆冲带。Valley 和 Ridge 中的双重层序被寒武系 Waynesboro 组页岩内的深层脱滑面所束缚，位于奥陶纪 Reedsville 页岩底部的一个拆离层之下。寒武纪-奥陶纪序列中 24 公里的缩短在 AP 中表示为 LPS。由于地球物理和露头数据的不足，已经假设志留系盐层拆离上方的 AP 中的所有地层都通过 LPS 加上非常温和的折叠而缩短。油气勘探的增加导致获得了新的高质量 3-D 地震和测井数据，这些数据表明志留系盐沼群到泥盆纪马塞勒斯页岩的地层正在通过各种机制缩短，包括楔式逆冲断层和折叠。通过运动学恢复和平衡的横截面，我们表明从 AP 表面暴露的岩石计算出的微尺度缩短幅度等于盐层拆离正上方志留系-下泥盆统单元的宏观缩短幅度。将我们的解释与之前发表的整个 AP 地震的解释进行比较，使我们能够扩展我们的模型，即通过 Marcellus 页岩在 Salina Group 中的缩短如何通过 Marcellus 页岩上方岩石中的 LPS 来平衡，以包括以前发表的研究的范围。由于富含碳氢化合物的 Marcellus 页岩是这种独特的志留系-泥盆纪变形组合的一部分，因此了解这些结构的几何形状对碳氢化合物采收的质量和数量具有潜在影响。