2023-06-28 ミネソタ大学
A relief map shows the Anatolian plate and its boundaries, with yellow arrows indicating the motion of the plates. Photo credit: Donna Whitney
◆研究結果は地質学の専門誌である『Geology』に掲載され、インフラや住宅配置の意思決定に役立つ情報を提供します。アナトリアンプレートの形成に関する議論がありましたが、この研究ではデータを用いて、約500万年前に形成されたと結論付けました。これにより、地域の地震活動や景観形成の理解が深まりました。
＜関連情報＞
- https://cse.umn.edu/college/news/researchers-unearth-mysteries-how-turkeys-east-anatolian-fault-formed
- https://pubs.geoscienceworld.org/gsa/geology/article/doi/10.1130/G51211.1/623411/Breaking-plates-Creation-of-the-East-Anatolian
プレートの破壊：東アナトリア断層、アナトリアプレート、地殻変動脱出システムの誕生
Breaking plates: Creation of the East Anatolian fault, the Anatolian plate, and a tectonic escape system
Donna L. Whitney;Jonathan R. Delph;Stuart N. Thomson;Susan L. Beck;Gilles Y. Brocard;Michael A. Cosca;Michael H. Darin;Nuretdin Kaymakcı;Maud J.M. Meijers;Aral I. Okay;Bora Rojay;Christian Teyssier;Paul J. Umhoefer
Geology Published:MAY 16, 2023
DOI:https://doi.org/10.1130/G51211.1
Lateral movement of lithospheric fragments along strike-slip faults in response to collision (escape tectonics) has characterized convergent settings since the onset of plate tectonics and is a mechanism for the formation of new plates. The Anatolian plate was created by the sequential connection of strike-slip faults following ≥10 m.y. of distributed deformation that ultimately localized into plate-bounding faults. Thermochronology data and seismic images of lithosphere structure near the East Anatolian fault zone (EAFZ) provide insights into the development of the new plate and escape system. Low-temperature thermochronology ages of rocks in and near the EAFZ are significantly younger than in other fault zones in the region, e.g., apatite (U-Th)/He: 11–1 Ma versus 27–13 Ma. Young apatite (U-Th)/He ages and thermal history modeling record thermal resetting along the EAFZ over the past ~5 m.y. and are interpreted to indicate thermal activity triggered by strike-slip faulting in the EAFZ as it formed as a through-going, lithosphere-scale structure. The mechanism for EAFZ formation may be discerned from S-wave velocity images from the Continental Dynamics–Central Anatolian Tectonics (CD-CAT) seismic experiment. These images indicate that thin but strong Arabian lithospheric mantle extends ~50–150 km north beneath Anatolian crust and would have been located near the present surficial location of the Bitlis-Zagros suture zone (co-located with the EAFZ in our study area) at ca. 5 Ma. Underthrusting of strong Arabian lithosphere facilitated localization of the EAFZ and thus was a fundamental control on the formation of the Anatolian plate and escape system.
