SGER AWARD: A Potential Example of Fold Growth Due to Kink-Band Migration on Near Earthquake-Cycle Timescales

在过去的20年里，构造地质学中最活跃的争论之一是扭结带运移形成的褶皱(如断层弯曲(FBF)和断层传播褶皱(FPF)的存在)。阿根廷西部一套明显显示扭带运移褶皱的基本几何特征的褶皱地貌面已经被识别出来。由于褶皱表面与1944年地震中的挠曲滑动面断裂密切相关，该遗址可能包含了在近地震周期时间尺度上扭折带迁移的第一个证据。这项探索性研究的主要目的是确定一套褶皱地貌面的结构几何是否与扭结带迁移褶皱生长的基本预测一致。然而，目前对它们的结构特征的了解是有限的，这排除了对它们的潜力的明确定义，从而为一般的扭结带迁移和折叠机制提供了新的见解。因此，寻求一笔探索性赠款，以从这些独特的、高度暴露的表面开发初始数据集，以更清楚地确定未来研究的潜力和方向。这项初步调查的主要目标包括：(1)了解褶皱在连续年轻地貌表面的空间和时间尺度上的几何演化；(2)详细描述褶皱生长和侵蚀/沉积不同步的活跃新生褶皱表面的地貌特征；(3)确定扭折带迁移褶皱的程度是褶皱生长的机制。这些数据和分析将有助于更清楚地阐明该地区该褶皱和其他正在生长的褶皱的结构和地貌演化、褶皱生长与侵蚀和沉积间隔期之间的相互作用以及褶皱在近地震时间尺度上的增量生长等问题。在这个时间尺度上对褶皱生长的认识的增加，对于理解与活动的隐伏断裂有关的地震危险性，解释同构造地层中的褶皱生长历史，在以同构造沉积为特征的盆地和涉及基底的逆冲区进行石油勘探，以及与断层相关的褶皱模式具有潜在的影响。

One of the most active debates in structural geology over the last 20 years has focusedon the existence of folds formed due to kink-band migration (e.g. the fault-bend (FBF) andfault-propagation (FPF) folds).A suite of folded geomorphic surfaces in western Argentinahave been identified that apparently display the essential geometrical characteristics of foldingdue to kink-band migration. Because the folded surfaces are closely associated with flexuralslip surface faulting in an earthquake in 1944,this site may contain the first evidence of kink-band migration on near earthquake cycle time scales. The primary purpose of this exploratoryresearch is to establish whether the structural geometry of a suite of folded geomorphicsurfaces is consistent with fundamental predictions of kink-band migration fold growth. Thepresent knowledge of their structural characteristics is limited, however, which precludes cleardefinition of their potential for providing new insight into kink-band migration and foldingmechanisms in general. Thus, an exploratory grant is sought to develop an initial data set fromthese unique, superbly exposed surfaces to define more clearly the potential and direction forfuture investigation. Key objectives of this initial investigation include:(1)understanding thegeometrical evolution of folds at the spatial and temporal scale of successively youngergeomorphic surfaces;(2)detailed characterization of the geomorphology of the surface of anactively growing emergent fold in which fold growth and erosion/deposition are out-of-phase;and (3)determination of the extent to which kink-band migration folding is the mechanism bywhich this fold is growing. These data and analyses will help to frame more explicitlyquestions regarding the structural and geomorphic evolution of this and other growing folds inthe region, the interplay between fold growth and intervening periods of erosion anddeposition, and the incremental growth of folds at near-earthquake time scales. Increased knowledge of fold growth on this time scale has potential impacts for understanding the earthquake hazard associated with active blind faults, the interpretation of fold growth history from syntectonic strata, petroleum exploration in basins characterized by syntectonic sedimentation and in regions of basement-involved thrusting, and fault-related fold models.