Late Cenozoic shift from extension to strike-slip stress regime in the west of the Biga Peninsula, NW Turkey

To the west of the Biga Peninsula, there are Paleozoic-Mesozoic metamorphic massifs and young fault systems that developed in different directions and periods. We investigated the types, formation times, and kinematics of these faults. Our field observations and kinematic studies show that there were three stress phases in the region between the Neogene and Quaternary. According to the analysis, in the first phase during the Miocene-Pliocene, the region was under NW-SE extension which affected western Anatolia. Right-lateral faults with left step-overs developed with the entrance of the North Anatolian Fault System into the Marmara region in the Middle-Late Pleistocene. This system started the second stage in the Late Pleistocene, and a short-lived NNE-SSW compression regime prevailed in the region. As a result, reverse faults and thrusts developed. In the third phase, During the Late Pleistocene-Holocene, the direction of extension turned to the NE-SW as the North Anatolian Fault System affected the region. The data we obtained from the region show that the West Anatolian Extensional System was effective during the Miocene-Pliocene. Then, particularly within the Late Pleistocene-Holocene period, the North Anatolian Fault System played the main role in the morphotectonic development of the Biga Peninsula and its surroundings.

Automated summary

The study shows the presence of Paleozoic-Mesozoic metamorphic massifs and young fault systems in the west of the Biga Peninsula. Three stress phases were identified in the region between the Neogene and Quaternary, with NW-SE extension dominating in the first phase, NNE-SSW compression prevailing in the second phase, and NE-SW extension in the third phase. The North Anatolian Fault System played a significant role in the morphotectonic development of the region, particularly in the Late Pleistocene-Holocene period.