Tectono-sedimentary evolution of a marginal fault: Insights from the Dead Sea Transform Fault System

Abstract

The Dead Sea Transform (DST), a prominent tectonic feature on Earth's crust, provides an exceptional natural laboratory for investigating the dynamic processes associated with continental rifting and its subsequent evolution. This study focuses on the sedimentary and tectonic evolution of the Yesha Fault, a marginal fault of the DST. Along the Yesha Fault, a distinct, elongated depression, known as the Yesha Valley was formed. Through detailed analysis of sedimentary sequences from boreholes and geochronological data obtained by optically stimulated luminescence and magnetostratigraphy, this research aims to refine the understanding of sedimentation patterns, rates, and tectonic activity associated with this marginal fault. The initial formation of the Yesha Valley, postdating the Brunhes-Matuyama reversal (∼773 ka), was driven by normal faulting, resulting in an accommodation space progressively infilled with clastic and aeolian sediments. The sedimentary record reveals four distinct cycles of calcic soil between ∼780 ka and ∼450 ka, indicative of short episodes of tectonic subsidence, each followed by a period of tectonic quiescence, during which carbonate accumulated and calcic soils have developed. Following ∼450 ka, the sedimentary sequence accumulated in the subsiding valley lacks evidence of abrupt tectonic events, suggesting a transition to a tectonic regime dominated by gradual creep. During the last glacial period, sedimentation is characterized by clay deposition, with more hydric conditions and increased organic content observed between 4 and 6.5 m, whereas the uppermost 2 m of the soil reflects the influence of recent anthropogenic activity. Sediment accumulation rates within the Yesha Valley exhibit considerable variability, ranging from 20.8 cm/ka to 1.8 cm/ka, with an average of 3.2 cm/ka. These rates are an order of magnitude lower than those observed in the adjacent Hula Basin, indicating a slower tectonic regime along the marginal Yesha Fault and valley.