Gravity modelling of a negative flower structure along the East Anatolian Fault: Western Lake Hazar Basin, Türkiye

This study presents a gravity-based structural interpretation of the Lake Hazar region in Elazığ, Türkiye, where a pull-apart basin has developed along the East Anatolian Fault. The basin overlies magmatic and metamorphic basement rocks and is filled with younger sedimentary deposits. To investigate the subsurface geometry and the trajectories of both the main fault and its sub-branches, seven north–south gravity profiles, along with a perpendicular control profile, were modeled using a four-unit geological framework and the Talwani method. Each profile was individually inverted to match observed anomalies, and the results were integrated into a comprehensive three-dimensional block model. The modelling reveals a well-defined negative flower structure in the eastern part of the study area, where the basin reaches a maximum width of ∼4000 m. This structure tapers westward, reflecting a gradual reduction in extensional deformation. Deformation becomes localized between profiles S4 and S5, where the modeled main fault exhibits a subtle S-shaped bend and intersects a lithological boundary between a sheeted dyke complex and more competent gneiss. West of this zone, extensional features dominated by blind normal faults appear, indicating a distinct tectonic regime likely related to the Doğanyol segment of the EAF. Across its onshore extent, the basin spans approximately 7000 m in length, with sedimentary thicknesses increasing toward the lake and reaching up to 90 m near its eastern margin. These findings provide the most detailed three-dimensional view of the Lake Hazar Basin to date, offering new insights into fault-controlled basin development and highlighting structurally significant zones that may have implications for seismic hazard assessment.