Formation of intracratonic basins by lithospheric shortening and phase changes: a case study from the ultra‐deep East Barents Sea basin
Formation of intracratonic basins by lithospheric shortening and phase changes: a case study from the ultra‐deep East Barents Sea basin
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岩石圈缩短和相变形成克拉通内盆地：以超深东巴伦支海盆地为例
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发表时间：
2013
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影响因子：
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通讯作者：
J. Faleide
中科院分区：
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作者：
Sébastien Gac;R. Huismans;N. Simon;Y. Podladchikov;J. Faleide
克拉通盆地大沉降的成因至今仍有争议。我们为这些盆地的形成提出了一个新的自洽模型，其中岩石圈缩短/屈曲引发地壳镁铁质非均质的变质和致密化。我们使用正演热机械有限元技术来评估这种机制的典型例子东巴伦支海盆地（EBB），其中一个非常大的补偿沉降，容纳高达20公里厚的沉积物序列，观察。动力学模型中的下地壳采用岩石学一致的密度进行建模，用于湿基性辉长岩成分，该成分取决于压力和温度，并考虑到高PT条件下的脱水。该模型成功地解释了EBB的主要特征，特别是在晚二叠世-早三叠世期间的大异常和快速沉降，其现今的几何形状以及没有显著的重力异常。
The origin of large subsidence in intracratonic basins is still under debate. We propose a new and self‐consistent model for the formation of those basins, where lithospheric shortening/buckling triggers metamorphism and densification of crustal mafic heterogeneities. We use a forward thermo‐mechanical finite element technique to evaluate this mechanism for the typical example of the East Barents Sea basin (EBB) where a very large and compensated subsidence, accommodating an up to 20‐km‐thick sediment succession, is observed. The lower crust in the dynamic model is modelled with petrologic‐consistent densities for a wet mafic gabbroic composition that depend on pressure and temperature taking into account dehydration at high PT conditions. The model successfully explains the main characteristics of the EBB, notably the large anomalous and fast subsidence during the Late Permian–Early Triassic, its present‐day geometry and the absence of a significant gravity anomaly.