HR: 1340h
AN: T53B-0486    [Abstracts]
TI: Niklas - a Hitherto Unknown Deep Magmatic Massif in the Eastern Mediterranean
AU: * Rybakov, M
EM: rybakov@gii.co.il
AF: Geophysical Institute of Israel, 6 Baal-Shem Tov St., P.O. Box 182, Lod, 71100 Israel
AU: Voznesensky, V
EM: v_voznesensky@hotmail.com
AF: Ben Gurion University of the Negev, P. O. Box: 653, Beer-Sheva, 84105 Israel
AU: Ben-Avraham, Z
EM: zvi@terra.tau.ac.il
AF: Tel Aviv University, Ramat Aviv, Tel Aviv, 69978 Israel
AB: A Niklas massif was discovered recompiling the gravity and magnetic maps and interpreting in 3-D mode all the available data in the area around Eratosthenes Seamount (ESM). The updated datasets clearly show two partially superimposed magnetic dipoles, which also correspond well to disturbances in the gravity field. The pronounced Eratosthenes magnetic anomaly (EMA) is only the positive part of the southeastern dipole. There is no large gravity anomaly here, however the specific gravity pattern corresponds to the magnetic body. The northwestern `magnetic dipole coincides with a prominent (about of 100mGal) gravity high that was recently delineated by Russian geophysicists. Such grav/mag combination allowed us to interpret the anomalies as being caused by a hitherto unknown dense and magnetic body which we have named the Niklas massif. The parameters and depth of causative bodies were calculated by inverse programs and forward modeling using the seismic refraction and reflection constraints. The reliability of the final model was verified using forward modeling. The magnetic data were interpreted by assuming an induced magnetization as the main magnetizing factor. The final model consists of two large compact features oriented NE-SW and located south of the Cyprian arc,as the Eratosthenes and Niklas bodies. The gravity and magnetic pattern of the Niklas is typical for the ophiolite massifs of the Eastern Mediterranean and Southern Turkey (Troodos, Hatay, Antalya). Based on this likeness we assume the Niklas composed by dense and magnetic ophyolites. This large (~100*75km) deep-seated (~7km) thick (~7km) massif is located ~95km southwest of Cyprus. We consider the Niklas as the south-most fragment of the large allochthonous ophiolite thrust slab including the Troodos massif. The tectonic situations of the Niklas area and the central segment of the Cyprian Arc are similar to that of the Eastern Taurus, Bayer-Bassit and Hatay areas. Interaction of the large Late Cretaceous overthrusts, younger Miocene reverse faults inclined mainly to north and Miocene- Pliocene normal faults and strike-slip faults revealed to the existing tectonic pattern. A system of reverse faults of the Cyprian arc separates the Niklas massif from the Troodos. This system is the main reason of the considerably lower level of the Niklas massif relative to the Troodos one. A pronounce tectonic boundary separates probably Niklas area from the Eratosthenes Block. Upper Cretaceous section of this block is sterile of ophiolites suggesting that during the Mesozoic the paleo-Eratosthenes area was located far from present-day position.
DE: 9345 Large bodies of water (e.g., lakes and inland seas)
DE: 8102 Continental contractional orogenic belts
DE: 3000 MARINE GEOLOGY AND GEOPHYSICS
DE: 1234 Regional and global gravity anomalies and Earth structure
DE: 1517 Magnetic anomaly modeling
SC: Tectonophysics [T]
MN: 2004 AGU Fall Meeting