Mud volcanoes and evaporite seismites in a tidal flat of northern Kuwait-implications for fluid flow in sabkhas of the Persian (Arabian) Gulf

摘要

This paper reports the first interpretative field map and stable isotope geochemistry of an exhumed Miocene inlier with conical mud volcanoes in a Persian (Arabian) Gulf salt flat (sabkha). In Kuwait, the siliciclastic low-heat flow margin of the northern gulf sector produced sedimentary conditions with numerous multilayered, unstable density gradients that were highly susceptible to recording liquefaction effects. The geotechnical characteristics of the sabkhas and the effects of local seismic activity resulted in ideal conditions in marginal sediments of Kuwait Bay, well suited for the development of deformation features. Three-dimensional, pseudo-biohermal exposures exhibit ellipsoidal pillows with craters separated by fluidized channels of chaotic orientation. The size and morphology of these structures together with co-genetic mud volcanoes are strongly influenced by sedimentary factors such as density gradients and tectonic events such as localized seismic activity, which caused mixing of fluids. Diapirs emerged concurrently with syn-sedimentary deformation, and the mud injection responded to episodic seismic activity. Interpretation based on previously published reflux models such as evaporative pumping and seawater flooding of coastal sabkhas is not applicable in this case. Rather, a model of focused ascent of brine initiated by episodic seismicity is proposed. Swarms of mud volcanoes represent new abiotic sedimentary features in sabkhas, but the per-ascensum nature of the fluid offers some comparisons to siliceous hot-water vents in south-eastern Brazil.