Tectonics in the Western Anatolian Extensional Province from sequence stratigraphic modeling of multichannel seismic data in the Gulf of Kusadasi

该项目将实现两个目标。该项目的第一部分将创建建模地层学的软件，地层学是指聚集在世界各地沉积盆地中的岩层。沉积层或地层的模式取决于海平面、构造和沉积物供应变化的复杂相互作用。该模型将适用于对从1万年到数百万年的时间尺度的地层学进行建模，将适用于许多环境，并广泛供其他科学家使用。对于这种类型的地层建模，公开可用的软件非常有限。该项目的第二部分将把新的软件包应用到土耳其西部附近的一个地区。这是一个地壳伸展导致陆地下沉并积累层层沉积物的地区。土耳其同事绘制的地层图显示了过去100万年来由于断层作用而导致的海湾沉降和抬升的复杂模式。在10万年的冰川周期中，海平面的变化使海岸线来回移动，为解释地层的年龄提供了一个框架。我们将建立地层学模型来确定构造，并为评估该地区的地震危险性做出贡献。它最近经历了6级以上的地震和7级以下的历史性地震。该项目将为一名年轻的土耳其科学家和一名美国本科生提供培训，增加他们对地层学进行定量建模和估计构造的能力。库萨达西湾是西安纳托利亚伸展省地震最活跃的地区之一，其活动断裂系统表现为北S伸展、东西向挤压、NE-西南向和NW-SE向走滑。土耳其高分辨率多道地震数据成像了一个伸展盆地，一个裂谷切割该地区的近海延伸，以及与之成高角度的两个隆起带。保存下来的沉积物包含13个地层层序，这些层序由具有褶皱状床形的进积三角洲组成，与1 Ma以来的冰川稳定旋回相关联。层序被不同方向的断层切割，并显示出与之相关的沉降和隆升模式。因此，这些矿床可以用来量化垂直运动和断层错动，从而约束该地区的构造。这些序列被解释为由于10万年的冰川-海平面循环，为破译该地区的构造和沉积史提供了一个明确的时间框架。我们建议使用数值层序地层学模型来再现地层几何形状并量化过去1 Ma以来的垂直运动。为了进行建模，我们将重写Sequence，这是一个在层序地层学时间尺度上建模地层学的代码。计算的沉降量将在计入伸展的均衡卸荷和沉积物的加载后用于估算伸展。结果将决定该地区正在经历的是纯粹的伸展、纯粹的剪切，还是两者的混合。随着时间的推移，断层的速率将被估计，并将指示变形是稳定的、逐渐增大的还是逐渐减弱的。对这种规模的变形进行定量估计对于了解爱琴海-安纳托利亚地区的复杂构造和更好地评估地震危险性是必要的。

This project will accomplish two goals. The first part of the project will create software for modeling stratigraphy, the layers of rock that accumulate in sedimentary basins around the world. The patterns of the sedimentary layers, or strata, depend on the complex interplay of changes in sea level, tectonics and the supply of sediments. The model will be appropriate for modeling stratigraphy over time scales of from 10,000 to millions of years, will be applicable to many settings, and made broadly available for use by other scientists. There is very limited publically available software for this type of stratigraphic modeling. The second part of the project will apply the new software package to an area off of western Turkey. This is an area where stretching of the crust is causing the land to sink and accumulate layers of sediment. Mapping of the layers by Turkish colleagues show a complex pattern of both subsidence and uplift of the bay over the last 1 million years due to faulting. Changes in sea level that shifted the coastline back and forth over the 100,000-year glacial cycles provide a framework for interpreting ages of the strata. We will model the stratigraphy to determine the tectonics and contribute to assessing the seismic hazard of this region. It has been subject to recent earthquakes up to M6 and historic earthquakes up to M7. The project will provide training for a young Turkish scientist, and a U.S. undergraduate student, adding to their abilities to quantitatively model stratigraphy and estimate tectonics.The Gulf of Kusadasi is one of the most seismically active regions of the Western Anatolian Extensional Province with active fault systems expressing N-S extension, E-W compression, and NE-SW and NW-SE strike slip. High-resolution Turkish multichannel seismic data image an extensional basin, the offshore extension of a rift cutting the area, and two uplifted zones at high angle to it. The preserved sediments contain thirteen stratigraphic sequences composed of prograding deltas with shingled clinoforms that have been correlated to glacioeustatic cycles going back to 1 Ma. The sequences are cut by faults with varied orientations, and they reveal associated patterns of subsidence and uplift. These deposits can thus be used to quantify the vertical motions and fault offsets, and thereby constrain the tectonics of the region. The sequences, interpreted as due to the 100,000 year glacio-eustatic cycles, provide a clear temporal framework for deciphering the tectonic and sedimentary history of the region. We propose to use a numerical sequence stratigraphic model to reproduce the stratal geometries and quantify the vertical motions over the last 1 Ma. In order to do the modeling, we will rewrite Sequence, a code for modeling stratigraphy at a sequence stratigraphic timescale. The calculated subsidence will be used to estimate the extension, after accounting for isostatic unloading by the extension and loading by the sediments. The results will determine whether the area is undergoing pure extension, pure shear, or a mixture of the two. The rates of faulting through time will be estimated and will indicate if the deformation is steady-state, waxing or waning. Quantitative estimates of deformation at this scale are necessary to understand the complex tectonics of the Aegean-Anatolian region, and to better evaluate the earthquake hazard.