Epeirogenic transients related to mantle lithosphere removal in the southern Sierra Nevada region, California: Part II. Implications of rock uplift and basin subsidence relations
Epeirogenic transients related to mantle lithosphere removal in the southern Sierra Nevada region, California: Part II. Implications of rock uplift and basin subsidence relations
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DOI：
10.1130/ges00816.1
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发表时间：
2013-06
期刊：
影响因子：
2.5
通讯作者：
J. Saleeby;Z. Saleeby;L. Pourhiet
中科院分区：
文献类型：
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作者：
J. Saleeby;Z. Saleeby;L. Pourhiet
我们调查假定的上新世-第四纪地幔岩石圈去除下的南部山脉内华达州地区使用合成的沉降数据从大峡谷，整个山脉内华达州的地貌关系。这些发现被用来测试岩石圈移除过程的热力学模型的结果和预测，这是特定于Sierra内华达州的，如本文引用的第一部分所附的论文中所介绍的。我们最成功的热力学模型和观测数据，它解释了进一步捆绑成一个综合的地形演化地球动力学模型的三维造陆变形场，主要影响了南部内华达山脉-圣华金盆地地区作为底层地幔岩石圈去除的结果。耦合的Sierra内华达州山脉和大峡谷盆地被认为是一个相对刚性的块体（Sierra内华达州微板块）在圣安德烈亚斯-沃克巷右旋板块接合系统内移动。我们的分析认识到，塞拉利昂内华达州拥有更大规模的本地和区域的古地形起伏，大峡谷弧前盆地具有可比的结构救济其主要地层，都可以追溯到白垩纪末。在考虑新生代晚期微板块的隆起和沉降时，必须考虑到这种古老的古地形。我们进一步认识到，新生代岩石和地表隆升必须从两个角度来考虑的地幔岩石圈去除驱动的局部造陆，和区域远场驱动的板块构造和区域上地幔浮力结构的造陆。位于Sierra内华达州基底北方和南部的上白垩统和下新生代海相地层的地层关系为新生代近巨型岩石隆升提供了证据。这种隆起可能具有正的，然后叠加负（沉降）阶段的救济生成，使净区域岩石和地表隆起。考虑到古老的古地形和远场驱动的区域隆起，留下了一个残留的模式，即1200米的东南部山脉顶部的岩石和类似的表面隆起，以及1700米的空间和时间相连的构造沉降在南部大峡谷所需的地幔岩石圈去除在晚新生代。这些值是接近我们的建模预测，但应用模型的结果，观察到的地质是复杂的空间和时间变化的区域构造，可能煽动地幔岩石圈去除，以及空间和时间变化的观察到的隆起和沉降模式。相当多的重点是这些时空变化模式，这是解释，以反映一个复杂的三维模式所造成的地幔岩石圈从下面的区域，以及它的造陆表达的逐步删除。最重要的因素是有力的证据表明，地幔岩石圈去除首先驱动的晚中新世-上新世的时间由东向西的模式拆沉，然后迅速过渡到一个南向北的模式拆沉在第四纪。
We investigate the putative Pliocene–Quaternary removal of mantle lithosphere from beneath the southern Sierra Nevada region using a synthesis of subsidence data from the Great Valley, and geomorphic relations across the Sierra Nevada. These findings are used to test the results and predictions of thermomechanical modeling of the lithosphere removal process that is specific to the Sierra Nevada, as presented in an accompanying paper referenced here as Part I. Our most successful thermomechanical model and the observational data that it explains are further bundled into an integrated physiographic evolution–geodynamic model for the three-dimensional epeirogenic deformation field that has affected mainly the southern Sierra Nevada–San Joaquin Basin region as a result of underlying mantle lithosphere removal. The coupled Sierra Nevada mountain range and Great Valley basin are recognized as a relatively rigid block (Sierra Nevada microplate) moving within the San Andreas–Walker Lane dextral plate juncture system. Our analysis recognizes that the Sierra Nevada possessed kilometer-scale local and regional paleotopographic relief, and that the Great Valley forearc basin possessed comparable structural relief on its principal stratigraphic horizons, both dating back to the end of Cretaceous time. Such ancient paleorelief must be accounted for in considering late Cenozoic components of uplift and subsidence across the microplate. We further recognize that Cenozoic rock and surface uplift must be considered from the perspectives of both local epeirogeny driven by mantle lithosphere removal, and regional far-field–forced epeirogeny driven by plate tectonics and regional upper-mantle buoyancy structure. Stratigraphic relations of Upper Cretaceous and lower Cenozoic marine strata lying on northern and southern Sierra Nevada basement provide evidence for near kilometer-scale rock uplift in the Cenozoic. Such uplift is likely to have possessed positive, and then superposed negative (subsidence) stages of relief generation, rendering net regional rock and surface uplift. Accounting for ancient paleorelief and far-field–driven regional uplift leaves a residual pattern whereby ∼1200 m of southeastern Sierra crest rock and similar surface uplift, and ∼700 m of spatially and temporally linked tectonic subsidence in the southern Great Valley were required in the late Cenozoic by mantle lithosphere removal. These values are close to the predictions of our modeling, but application of the model results to the observed geology is complicated by spatial and temporal variations in the regional tectonics that probably instigated mantle lithosphere removal, as well as spatial and temporal variations in the observed uplift and subsidence patterns. Considerable focus is given to these spatial-temporal variation patterns, which are interpreted to reflect a complex three-dimensional pattern resulting from the progressive removal of mantle lithosphere from beneath the region, as well as its epeirogenic expressions. The most significant factor is strong evidence that mantle lithosphere removal was first driven by an east-to-west pattern of delamination in late Miocene–Pliocene time, and then rapidly transitioned to a south-to-north pattern of delamination in the Quaternary.