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

近20年来，构造地质学中最活跃的争论之一是是否存在因折带迁移而形成的褶皱（如断层弯曲褶皱（FBF）和断层传播褶皱（FPF））。 由于褶皱面与1944年地震中的挠曲滑动面断层密切相关，该场地可能包含近地震周期时间尺度上扭结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表面的结构几何形状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，这就排除了对它们的潜力的明确定义，从而为扭结带的迁移和折叠机制提供了新的见解。 因此，我们寻求一笔探索性的赠款，从这些独特的、极好的暴露表面开发一个初始数据集，以更清楚地确定未来研究的潜力和方向。 初步研究的主要目标包括：（1）了解褶皱在空间和时间尺度上的几何演化，这些空间和时间尺度上的褶皱逐渐变小;（2）详细描述一个活跃生长的突现褶皱表面的地貌特征，其中褶皱生长和侵蚀/沉积是异相的;（3）确定扭结带迁移褶皱的程度是该褶皱生长的机制。 这些数据和分析将有助于框架更明确的问题，关于这个和其他增长褶皱的结构和地貌演化在该地区，褶皱的增长和侵蚀和沉积之间的相互作用，以及褶皱的增量增长在近地震的时间尺度。在这个时间尺度上增加对褶皱生长的了解，对于理解与活动盲断层相关的地震危险性、从同构造地层解释褶皱生长历史、在以同构造沉积为特征的盆地和基底参与的逆冲推覆区域进行石油勘探以及与断层相关的褶皱模型具有潜在的影响。

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.