Geodynamic reconstruction of an accreted Cretaceous back-arc basin in the Northern Andes
Geodynamic reconstruction of an accreted Cretaceous back-arc basin in the Northern Andes
复制标题
DOI：
10.1016/j.jog.2018.09.008
复制
发表时间：
2018-11-01
影响因子：
2.3
通讯作者：
Mueller, R. Dietmar
中科院分区：
文献类型：
--
作者：
Braz, Carmen;Seton, Maria;Mueller, R. Dietmar
俯冲、弧后盆地形成、地体增生和压扭剪切的复杂历史是侏罗纪以来加勒比海和南美北部边缘演化的特征。该地区的定量板块构造重建不包括有地质和地球物理观测的侏罗纪-白垩纪弧后地体。我们根据地质观测和地震层析成像模型进行了修订后的板块构造重建，以约束加勒比地区西缘东部 Panthalassa 的侏罗纪白垩纪俯冲历史。该重建考虑了北安第斯弧后盆地于 145 Ma 开启，Quebradagrande 弧后于 120 Ma 关闭，随后从 100 Ma 开始沿南美边缘发生地体增生和向北平移。通过使用 CitcomS 与全球数值地幔对流模型耦合，对这种运动学重建进行了针对先前发布的两个构造重建的测试。模拟地幔结构与层析成像地幔结构的比较表明，需要在南美洲边缘外侧俯冲，以重现南美洲地下 500-2000 公里深度的纵波和横波地震层析成像中所成像的中地幔正地震异常。此外，我们还表明，该俯冲带可能是由弧后盆地产生的，该弧后盆地在白垩纪期间沿着安第斯山脉北部发育，通过从 145 Ma 开始的海沟回滚并在 100 Ma 关闭。 Quebradagrande弧后盆地与安第斯山脉南部的Rocas Verdes弧后盆地同时打开，与后退板片后面地幔物质回流的模型一致，这可以解释为什么在晚侏罗世-早白垩世期间，沿着安第斯边缘的秘鲁和智利部分的伸展没有经历完全的地壳破裂和弧后打开。
A complex history of subduction, back-arc basin formation,terrane accretion and transpressional shearing characterizes the evolution of the Caribbean and northern South American margin since Jurassic times. Quantitative plate tectonic reconstructions of the area do not include Jurassic-Cretaceous back-arc terranes of which there are both geological and geophysical observations. We developed a revised plate tectonic reconstruction based on geological observations and seismic tomography models to constrain the Jurassic Cretaceous subduction history of eastern Panthalassa, along the western margin of the Caribbean region. This reconstruction considers the opening of a Northern Andean back-arc basin at 145 Ma, the Quebradagrande back arc, closing at 120 Ma and followed by terrane accretion and northward translation along the South American margin starting at 100 Ma. This kinematic reconstruction is tested against two previously published tectonic reconstructions via coupling with global numerical mantle convection models using CitcomS. A comparison of modelled versus tomographically imaged mantle structure reveals that subduction outboard of the South American margin, lacking in previous tectonic models, is required to reproduce mid-mantle positive seismic anomalies imaged in P- and S-wave seismic tomography beneath South America, 500-2000 km in depth. Furthermore, we show that this subduction zone is likely produced by a back-arc basin that developed along the northern Andes during the Cretaceous via trench roll-back from 145 Ma and was closed at 100 Ma. The contemporaneous opening of the Quebradagrande back-arc basin with the Rocas Verdes back-arc basin in the southern Andes is consistent with a model that invokes return flow of mantle material behind a retreating slab and may explain why extension along the Peruvian and Chilean sections of the Andean margin did not experience full crustal break-up and back-arc opening during the late Jurassic-early Cretaceous Period.