Fluids from Ocean and Mantle may Ascend and Descend from One to Another along Passive Continental Margins such as the Northern Gulf of Mexico

摘要

Major normal and growth faults are known to extend from seafloor through to base of sediment wedge, with origins generally occurring along the then shelf break/ uppermost slope with overall less contemporary tectonics farther landward. Loci of extensional tectonics proceeds basinward as entire sediment mass migrates offshore, also incorporating lesser sediment depocenters due to sea level oscillations. These wedge-transiting faults appear to often terminate into semi-plastic salt accumulations. Uncon-solidated clay deposition, dominated by electromagnetics, can create breakage/weakness zones along which extruded fluids from dewatering can migrate. Thus, the seafloor expression of significant faults can range from well-defined fault-breaks to varying concentrations/domains of clay-sized particles. Let us grant a continental margin under extension from rifting while deepening into a new ocean basin, normal faults seemingly occur within subsiding crust. Given synchroneity of extension and subsidence in sediments and crust, breakage zones might coincide in both. The upper crust is brittle. Lower crust temperature and pressure suggest semi-plasticity, with dislocations between separate masses. Between upper and lower crust would be transitional crust, possibly with fluid-injection along brittle breakages. As measured by earthquake seismology, crust maintains constant densities of 3.3 g/cm3 for oceanic and 2.7 g/cm3 for continental crust with a transition between them; such density transition mandates the Airy-Pratt controversy is unresolved. Mantle, plastic and heterogeneous, contains convection cells with lateral extents from 10-100 km to basin spanning within a hierarchy of vertical to horizontal flows. Ocean and mantle fluids could find avenues to transit from one to another.