How sediment promotes narrow rifting: Application to the Gulf of California
How sediment promotes narrow rifting: Application to the Gulf of California
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DOI：
10.1029/2008tc002394
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发表时间：
2009-08-22
期刊：
影响因子：
4.2
通讯作者：
Buck, W. Roger
中科院分区：
文献类型：
--
作者：
Bialas, Robert W.;Buck, W. Roger
如果与地壳减薄有关的重力应力变化大到足以影响伸展模式，那么沉积作用也应该影响该模式。我们认为沉积物的重量减少了由局部地壳减薄引起的地壳浮力差异，使裂谷更容易以狭窄的裂谷模式延伸。我们研究了大量的非本地衍生沉积物的沉积对伸展样式的影响，使用二维，区域尺度的数值实验，扩展厚大陆地壳与不同的初始热条件，几何形状，流变参数和沉积特性。根据初始模型条件，在厚大陆地壳裂谷的开始发生在窄裂谷，宽裂谷，或核心复杂的模式。随着拉张作用的继续，所有的断块最终都转变为一个狭窄的裂陷模式。对于一个处于宽裂谷模式的系统来说，中等到快速的沉积缩短了过渡到窄裂谷所需的时间。在加州湾，伸展样式的变化与沉积厚度相关，北部比南部更早过渡到狭窄裂谷。我们比较我们的模型结果的伸展历史的加州，沉积物可能造成的北方和北中央域的海湾（德尔芬-Tiburon和瓜伊马斯段）过渡到狭窄的裂谷南部中央域（阿拉尔孔段）之前。引用：Bialas，R. W.，和W. R. Buck（2009），How sediment promotes narrow rifting：Application to the Gulf of加州州，Tectonics，28，TC 4014，doi：10.1029/2008TC 002394.
If the gravitational stress changes related to crustal thinning are large enough to affect the mode of extension, then sedimentation should also affect that mode. We propose that the weight of sediments reduces the difference in crustal buoyancy forces caused by local crustal thinning, allowing a rift to extend more easily in a narrow rift mode. We examine the effect of deposition of large amounts of nonlocally derived sediment on extensional style using two-dimensional, regional-scale numerical experiments of extending thick continental crust with varied initial thermal conditions, geometries, rheological parameters, and sedimentation properties. Depending on initial model conditions, the onset of rifting in thick continental crust occurs in the narrow rifting, wide rifting, or core complex mode. With continued extension, all cases eventually transition to a narrow rifting mode. For a system in wide rift mode, moderate to fast sedimentation shortens the time needed to transition to a narrow rift. In the Gulf of California, changes in extensional style correlate with sediment thickness, with an earlier transition to narrow rifting in the north versus the south. We compare our model results to the extensional history of the Gulf of California, where sediments may have caused the northern and north central domain of the gulf (Delfin-Tiburon and Guaymas segments) to transition to narrow rifting before the south central domains (Alarcon segment). Citation: Bialas, R. W., and W. R. Buck ( 2009), How sediment promotes narrow rifting: Application to the Gulf of California, Tectonics, 28, TC4014, doi:10.1029/2008TC002394.