Tectonic control on sedimentary facies pattern and sediment accumulation rates in the Miocene foreland basin of the southern Alborz mountains, northern Iran
Tectonic control on sedimentary facies pattern and sediment accumulation rates in the Miocene foreland basin of the southern Alborz mountains, northern Iran
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DOI：
10.1029/2008tc002278
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发表时间：
2008-12
期刊：
影响因子：
4.2
通讯作者：
P. Ballato;N. Nowaczyk;A. Landgraf;M. Strecker;A. Friedrich;S. Tabatabaei
中科院分区：
文献类型：
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作者：
P. Ballato;N. Nowaczyk;A. Landgraf;M. Strecker;A. Friedrich;S. Tabatabaei
伊朗北方的南部阿尔博尔兹山脉是阿拉伯/欧亚碰撞带的一个组成部分。通过对阿尔博尔茨山南部Eyvanekey地层剖面的磁性地层学和岩石磁学研究，揭示了阿尔博尔茨前陆盆地沉积相迁移的时空特征。该剖面由三个向上变粗的单元（单元1、2和3）组成，包括上红层和下红层。我们的数据表明，上红组的沉积时间为17.5和7.5 Ma之间，而Eschardarreh组顶部的沉积年龄可外推至17.2 Ma。缓慢的沉积物堆积速率与沉积相关，沉积相包括向上变粗的单元。这可能是前陆内隆起（单元1和2）和盆地反转的结果，可能与位于近端前陆（单元3）的生长向斜有关。相比之下，每个循环底部的细粒地层与更快的沉积物积累速率相关，证明在逆冲加载过程中弯曲盆地沉降增强。在相对快速的沉积物堆积过程中（单元2顶部）也发生了粗粒相的沉积作用，这表明粗粒沉积物的流入超过了近端前陆的储存能力。因此，尽管整体向南传播的变形到南部Alborz前陆，轨迹的活动变形必须迁移来回的时间尺度约为0.7至2马。
The southern Alborz mountains of northern Iran are an integral part of the Arabia/Eurasia collision zone. A magnetostratigraphic and rock magnetic investigation of the Eyvanekey stratigraphic section in the southern Alborz mountains reveals the spatiotemporal character of sedimentary facies migration in the Alborz foreland basin. The section constitutes three coarsening upward units (units 1, 2, and 3), comprising the Upper Red and Hezardarreh formations. Our data reveal that the Upper Red Formation was deposited between 17.5 and 7.5 Ma, while the depositional age of the top of the Hezardarreh Formation can be extrapolated to ∼6.2 Ma. Slow sediment accumulation rates correlate with sedimentary facies comprising prograding, coarsening‐upward units. This is likely the result of intraforeland uplift (units 1 and 2) and basin inversion, probably associated with a growth syncline located in the proximal foreland (unit 3). In contrast, fine‐grained strata at the bottom of each cycle are associated with faster sediment accumulation rates, testifying to enhanced flexural basin subsidence in the course of thrust loading. Progradation of coarse‐grained facies also occurred during relatively fast sediment accumulation (top of unit 2), suggesting that the influx of coarse‐grained sediment outpaced the storage capacity of the proximal foreland. Thus, despite an overall southward propagation of deformation into the southern Alborz foreland, the locus of active deformation must have migrated back and forth on a time scale of circa 0.7 to 2 Ma.