HR: 1340h
AN: GP33A-0102    [Abstracts]
TI: Tectonic Evolution of the Hatay Ophiolite of SE Turkey: Implications for the Evolution of the Eastern Mediterranean Neotethys
AU: * Inwood, J
EM: ji18@le.ac.uk
AF: University of Leicester, Department of Geology, University Road, Leicester, LE1 7RH United Kingdom
AU: * Inwood, J
EM: ji18@le.ac.uk
AF: University of Plymouth, School of Earth, Ocean and Environmental Sciences, Drake Circus, Plymouth, PL4 8AA United Kingdom
AU: Morris, A
EM: A.Morris@plymouth.ac.uk
AF: University of Plymouth, School of Earth, Ocean and Environmental Sciences, Drake Circus, Plymouth, PL4 8AA United Kingdom
AU: Anderson, M
EM: M.Anderson@plymouth.ac.uk
AF: University of Plymouth, School of Earth, Ocean and Environmental Sciences, Drake Circus, Plymouth, PL4 8AA United Kingdom
AU: Robertson, A H
EM: Alastair.Robertson@ed.ac.uk
AF: University of Edinburgh, School of GeoSciences, Grant Institute, The King's Buildings, West Mains Road, Edinburgh, EH9 3JW United Kingdom
AU: Unlugenc, U
EM: uunlugenc@cu.edu.tr
AF: Cukurova University, Geological Engineering Department, Adana, 01330 Turkey
AB: Late Cretaceous ophiolitic rocks are found throughout the eastern Mediterranean and are remnants of small Neotethyan ocean basins destroyed during collision of the African and Eurasian plates. The Troodos (Cyprus), Hatay (SE Turkey) and Baer Bassit (NW Syria) ophiolites are remnants of the southernmost basin. The Troodos ophiolite is relatively undeformed and remains in a pre-emplacement setting, in contrast to Hatay and Baer Bassit which were emplaced as a thrust sheet onto the Arabian continental margin in the Maastrichtian. Previous paleomagnetic investigations identified a regionally significant Late Cretaceous-Eocene 90 degree anticlockwise intraoceanic rotation of the Troodos `microplate' (Clube and Robertson 1986). More recent data from the highly dismembered Baer Bassit ophiolite (Morris et al. 2002) indicate extreme anticlockwise rotations of the leading edge of the emplaced sheet. Kilometric scale variability makes their relationship to the Troodos rotation difficult to determine. Here we present the first paleomagnetic data from the more coherent Hatay ophiolite. These data provide the key that allows the regional pattern of rotations to be established for the first time. Paleomagnetic results have been obtained from various levels of the ophiolite. All retain stable components of magnetization with directions unrelated to the present day field. An inclination-only tilt test applied to data from sites with paleohorizontal control indicates that magnetization pre-dates deformation. This is supported by rock magnetic analyses that indicate a magnetic mineralogy consistent with acquisition of remanences soon after crustal genesis. The overall westerly mean direction of magnetization indicates a large bulk anticlockwise rotation of the Hatay ophiolite. Localised minor rotations revealed by variability in tilt corrected declinations may be readily related to the deformation history of the ophiolite determined from complementary structural analyses. New paleomagnetic data from the authochthonous, post-emplacement sedimentary cover sequences demonstrate that the large rotations observed in the Hatay and Baer Bassit ophiolites occurred prior to deposition of these sequences. Comparison with the history of Troodos microplate rotation as recorded by its continuous sedimentary cover suggests a common intraoceanic origin for a significant component of rotation. Hence, the combined datasets from all three ophiolites are consistent with a regional tectonic history involving: (i) intraoceanic bulk rotation of a coherent region of oceanic crust within the southern Neotethyan basin; (ii) emplacement of part of the rotated unit onto the Arabian platform; and (iii) subsequent minor post-emplacement rotations that locally modify the bulk rotation angle. These results have important implications for the evolution of the eastern Mediterranean, requiring re-assessment of the scale of the "Troodos" microplate. Furthermore, back-stripping of rotations observed in the sheeted dyke complexes of the various ophiolites reveals a primary variation in dyke strike (and hence spreading axes) within the southern Neotethyan ocean. This suggests formation of the ophiolites within a complex spreading system, analogous in many respects to fast spreading marginal basin systems of the modern oceans.
DE: 1500 GEOMAGNETISM AND PALEOMAGNETISM
DE: 1525 Paleomagnetism applied to tectonics: regional, global
DE: 3042 Ophiolites (8140)
DE: 8140 Ophiolites (3042)
SC: Geomagnetism and Paleomagnetism [GP]
MN: Fall Meeting 2005