Paper No. 7
Presentation Time: 9:00 AM-6:00 PM
CONSTRAINTS ON THE EVOLUTION OF THE MARMARA SEA TRANSFORM BASIN FROM HIGH-RESOLUTION SEISMIC REFLECTION DATA
SHILLINGTON, Donna J., Lamont-Doherty Earth Observatory of Columbia University, 61 Route 9W, Palisades, NY 10964, SORLIEN, Christopher C., Institute for Crustal Studies, University of California Santa Barbara, Santa Barbara, CA 93106, SEEBER, Leonardo, Seismology Geology and Tectonophysics, Lamont-Doherty Earth Observatory, 61 Route 9W, PO Box 1000, Palisades, NY 10964-8000, KURT, Hulya, Istanbul Technical University, Istanbul, 34390, Turkey, STECKLER, Michael, Lamont-Doherty Earth Observatory, 61 Route 9W, PO Box 1000, Palisades, NY 10964-8000 and TAMAM SCIENTIFIC PARTY, 2008 and 2010, Lamont-Doherty Earth Observatory, 61 Route 9W, PO Box 1000, Palisades, NY 10964, djs@ldeo.columbia.edu
The North Anatolian Fault (NAF) accommodates ~23-25 mm/yr of present-day right-lateral motion between the Anatolian and Eurasian plates, which occurs primarily by recurrent large earthquakes. This fault passes close to population centers in northern Turkey, and recent large earthquakes have had disastrous consequences (e.g., the 1999 7.4 Izmit earthquake). Although it is one of the best-studied transform systems in the world, many questions remain about the temporal evolution of the NAF, particularly near Istanbul, where it splinters into multiple strands, some of which are submerged under the Marmara Sea. We present constraints on the temporal evolution of the North Anatolian Fault and other fault strands beneath the Marmara Sea over the last ~0.5 m.y. from high-resolution multi-channel seismic (MCS) reflection data acquired with the R/V
K. Piri Reis in 2008 and 2010 during the ‘TAMAM’ program.
These data yield several fundamental new insights into the evolution of the Sea of Marmara transform basin. Until recently, a stratigraphic age model to characterize late Quaternary tectonics of the area has been lacking. High-resolution MCS data imaged a stack of progressively tilted glacial period deltas within the North Imrali basin. Seismic stratigraphy, tilting, fault vertical separations, and sediment volume was used to develop an age model for five horizons between 109 and 540 ka. We used TAMAM MCS data plus existing deep-penetration, low-resolution migrated MCS data for seismic stratigraphic interpretation to extend horizons associated with these low-stand deltas throughout much of the Marmara basin. This work demonstrates that most of plate motion for at least the last ~0.5 m.y. was taken up on the northern branch of the North Anatolian fault (NAF), and that the slip rates and configuration of the fault system over this time frame have been similar to the present. These data also reveal the presence of wide-spread downslope creep on the margins of the transform basin. The temporal and spatial evolution of the creep folds is clearly related to rapid tilting in this tectonically active transform basin, and they thus might serve as an important tool for reconstructing tilting in this active basin. They may also diminish hazards associated with catastrophic collapse by the loss of gravitational potential collapse.
