Subsidence basin

Fuentes, F., Feraud, G. Aguire, L., Morata, D. 2005. " °Ar/ Ar dating of volcanism and subsequent very low-grade metamorphism in a subsiding basin example of the Cretaceous lava series from central Chile. Chemical Geology, 214, 15-177. 

Fig. 2.10 Rock beds in a subsidence basin. The part above the terminal base of drainage, for example, the sea, functions as a through-flow system (arrows). The deeper rock beds are fossil through-flow systems that host stagnant groundwater as they are (1) covered by impermeable rocks, (2) bisected by plastic impermeable rocks that have been squeezed into stretch joints in the competent rock beds and in between bedding plane thrusts, and (3) placed in a zone of zero hydraulic potential.

Fig. 2.21 An example of a cross-section depicting hundreds of kilometers across a subsidence basin, with stratigraphic units assumed to act as through-flow ducts (the Great Artesian Basin, Australia) (following Seidel, 1980).

Exercise 14.7 Figure 14.2 incorporates a large body of noble gas data obtained from a huge subsidence basin. What can be learned from the reported noble gas fingerprints ... 

Groundwater flow in actively filling and subsiding basins... 

The hydrocarbons expelled from the mature source rocks in separate phase, may initially occur in a very finely dispersed state. At depths corresponding to the peak phase of hydrocarbon expulsion in actively filling and subsiding basins, the hydrodynamic condition is characterized by the intermediate or the deep subsystem of burial-induced groundwater flow. Initially, the very finely dispersed hydrocarbons will move along with the burial-induced groundwater... 

The qualitative assessment of the hydrodynamic conditions in a filling and subsiding basin results in the identification of the areal distribution of the different subsystems of burial-induced groundwater flow, the general pattern of lateral burial-induced groundwater flow and the identification of zones of concentrated upward directed flow of groundwater. 

When a subsiding basin is surrounded by continental areas or when part of the basin has emerged and stabilized above sea level, the hydrodynamic characteristics of such basins reflect the interaction of burial- and gravity-... 

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