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Group 1 – LAD | Poster Abstracts
Lithospheric Architecture and Dynamics (LAD)
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INTERNATIONAL COLLABORATION IMAGES THE NORTH ANATOLIAN FAULT
SYSTEM IN MARMARA SEA, TURKEY: SUBSIDED LOWSTAND DELTAS,
ONLAPPING BASIN FILL, THRUST-FOLD TRANSVERSE RIDGES, TRANSTENSION,
AND DISTRIBUTED ACTIVE FAULTING TAMAM Scientific Party*
We collected high-resolution multichannel seismic reflection (MCS) data to image the North
Anatolian Fault (NAF) and basin sediments in the Marmara Sea. The North strand of the NAF,
passing closest to Istanbul, is considered to carry most of the current and late Holocene plate
motion, based on GPS data, historic seismicity and onshore trenching. Three >1200 m-deep
bathymetric basins and the 800 m-deep Kumburgaz basin are arrayed along the northern NAF.
Our results may support long-standing yet still controversial suggestions that the NW-SE releasing
segment of the northern NAF is non-vertical with a normal component of slip, and that this
ongoing process is responsible for the basin. However, additional advanced data processing
(migration) is planned to better image the fault geometry. Extension or transtension, however, are
by no means universal within Marmara Sea. We image transverse (NE-SW) ridges between the
basins to be thrust-related anticlines. We also imaged large-scale deep-seated landslide complexes
on the basin flanks that are important contributors to basin fill.
Our chirp data image several strands of the southern fault system, 50 km south of the northern
NAF, to offset strata above the Last Glacial Maximum unconformity. A WNW-striking segment of
the intervening Imrali fault system is associated with normal-separation, 300 m-high sea floor
scarps, and numerous young secondary faults in its hanging-wall. There, stacked low-stand shelf
edge deltas, whose tops were formed near sea level or lake level, are now >400 deep. Sea level and
climate cycles control delivery of sediment to the deep basins, resulting in a repeating pattern of
onlapping fill on the progressively-tilting basin flanks. We will attempt to relate the onlapping fill
events to the succession of low-stand deltas by tracing horizons via regional strike profiles.
MCS profiles with simple migrations indicate that the E-W segment of the NAF through
Kumburgaz basin adjacent to western Istanbul is associated with shortening structures. The deep
part of a N-dipping transpressional fault there would be closer to western Istanbul than would a
south-dipping transtensional NAF.
*Selin D. Akhun, A. Evren Buyukasik, Melis Cevatoglu, Günay Çifçi, Süleyman Coskun, Emin
Demirbag, John Diebold, Derman Dondurur, Savas Gurcay, Caner Imren, H. Mert Kucuk, Hülya
Kurt, Pinar G. Özer, Emre Perinçek, Leonardo Seeber, Donna Shillington, Christopher C. Sorlien,
Michael Steckler, and Duygu Timur
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SOUTHERN CALIFORNIA MODELING OF GEODYNAMICS IN 3D (SMOG3D):
TOWARD QUANTIFYING THE STATE OF TECTONIC STRESS IN THE SOUTHERN
CALIFORNIA CRUST Fay NP, Becker TW, and Humphreys ED
We present results from numerical modeling of three-dimensional geodynamics of the southern
California lithosphere. Our primary objective is to quantify how faults are loaded and, more
generally, the state of stress in the southern California crust. We evaluate how buoyancy and
rheology control this stress state, and aim to better understand the relationships to active
deformation and earthquakes, horizontal coupling between tectonic plates, and the vertical
coupling between the lithosphere and upper mantle. We use a 3D finite element approach
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