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

根据库萨达斯湾多道地震数据的层序地层模型研究西安纳托利亚伸展省的构造

• 批准号: 1559098
• 负责人: Michael Steckler
• 金额: $ 24.62万
• 依托单位: Columbia University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-03-15 至 2022-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1559098&HistoricalAwards=false
• 关键词: Tectonics; Western; Anatolian; Extensional; Province

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.

该项目将实现两个目标。 该项目的第一部分将创建用于建模地层学的软件，地层学是在世界各地沉积盆地中积累的岩石层。 沉积层或地层的模式取决于海平面变化、构造和沉积物供应的复杂相互作用。 该模型将适用于模拟从10，000到数百万年的时间尺度上的地层学，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，可利用的软件非常有限。 该项目的第二部分将把新的软件包应用于土耳其西部的一个地区。 这是一个地壳拉伸导致陆地下沉并积累沉积物层的地区。土耳其同事绘制的地层图显示，在过去的100万年里，由于断层作用，海湾出现了复杂的沉降和隆起模式。在10万年的冰川循环中，海平面的变化使海岸线来回移动，这为解释地层的年龄提供了一个框架。我们将建立地层模型，以确定构造，并有助于评估该地区的地震危险性。最近发生了6级地震，历史上发生了7级地震。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，提高他们定量建模地层学和估计构造的能力。库萨达斯湾是西安纳托利亚伸展省地震最活跃的地区之一，其活动断层系统表现为南北向伸展、东西向挤压、东北-西南和西北-东南走向滑动。 高分辨率的土耳其多道地震数据图像的伸展盆地，裂谷切割该地区的离岸延伸，并在高角度的两个隆起带，它保存的沉积物包含13个地层层序组成的叠置三角洲与叠瓦状的斜坡，已被相关的冰川海平面变化的周期可以追溯到1马。这些层序被不同方向的断层切割，并显示出相关的沉降和抬升模式。因此，这些沉积物可以用来量化垂直运动和断层偏移，从而限制该地区的构造。这些序列被解释为10万年的冰川-海平面变化周期，为解释该地区的构造和沉积历史提供了一个清晰的时间框架。我们建议使用一个数值层序地层模型来重现地层几何形状和量化的垂直运动在过去的1马。为了进行建模，我们将重写层序，这是一个在层序地层时间尺度上进行地层建模的代码。在考虑了延伸的均衡卸载和沉积物的加载后，计算的沉降将用于估计延伸。结果将确定该区域是否经历纯拉伸、纯剪切或两者的混合。将估计随时间推移的断层速率，并将指示变形是稳定状态、增强还是减弱。为了了解爱琴海-安纳托利亚地区复杂的构造，并更好地评估地震危险，有必要对这种规模的变形进行定量估计。