Carbonate Platform Models in Strike-Slip Settings
Steven L. Dorobek
Texas A&M University, College Station, TX
Carbonate platforms may form in many plate-boundary and plate-interior settings where strike-slip deformation occurs. Platform types can be classified in a kinematic sense, according to whether they are syn-tectonic (i.e., platforms cut by strike-slip faults during platform growth), post-tectonic (i.e., platforms grow on antecedent strike-slip structures that formed during previous phases of deformation), or tectonically segmented (i.e., cut by younger strike-slip faults after platform growth).
Syn-tectonic strike-slip platforms are typically isolated platforms that develop on faulted anticlinal or steep-sided, fault-bounded highs. Flower structures are common during early stages of strike-slip deformation before linkage of isolated strike-slip fault segments and provide ‘broken' antiformal substrates for isolated platforms with complex internal growth strata. In plan view, flower structures create elongate, ovoid platforms with limited areal dimensions. With continued strike-slip displacements, isolated fault segments often link and form more regional strike-slip fault zones that may begin to accommodate lateral offset along the boundaries of crustal blocks. Some component of vertical displacement typically accompanies strike-slip offset, producing structural relief between fault-bounded basement highs to adjacent basinal areas. These more regional strike-slip fault systems may control platform-margin profiles for the entire growth history of the platform, especially where adjacent basinal areas remain underfilled. The width of carbonate platforms also may be entirely controlled by horizontal spacing between the through-going strike-slip fault zones. Small isolated platforms may coalesce into larger composite platforms where displacements on strike-slip faults are slow to accrue and platforms have the ability to fill any newly generated tectonic accommodation.