Post-early Messinian counterclockwise rotations on Crete: implications for Late Miocene to Recent kinematics of the southern Hellenic arc

Abstract

Most geodynamical models for the kinematics of the central Mediterranean recognise that major tectonic rotations must have played an important role during the Neogene. The Hellenic arc is believed to have been subjected to clockwise rotations in the west and counterclockwise rotations in the east, while the southern part (Crete) shows no rotations (Kissel and Laj, 1988). Many qualitative and quantitative models are based on the idea that Crete did not rotate. We present new palaeomagnetic data which show that post-early Messinian counterclockwise rotations have occurred on Crete. The amount of counterclockwise rotation generally varies between 10º and 20º, but in central Crete much larger rotations (up to ¾40º counterclockwise) were found. Only a few sections did not show any rotation. The anisotropy of magnetic susceptibility (AMS) shows lineations, which are consistently WNW-ESE throughout Crete, indicating post-rotational WNW-ESE extension, or NNE-SSE compression. The observed counterclockwise rotations are consistent with the results of tectonic modelling by Ten Veen and Meijer (1998). The latter study compares the late-Middle Miocene to Recent kinematics with modelled intra-plate stresses for various possible distributions of plate boundary forces. Observations reveal that motion along left-lateral and right-lateral faults occurred during the Pliocene. The model analysis shows these motions to be consistent with transform resistance along the eastern segment of the overriding margin. The counterclockwise block rotations observed by us are probably a consequence of displacements along the left-lateral and right-lateral faults and could reflect a similar tectonic regime that involved transform resistance.

Shallow bias in Mediterranean paleomagnetic directions caused by inclination error

“…Numerous paleomagnetic studies have been performed on the late Miocene sediments from Crete, especially focussing on vertical axis rotation (e.g., [17,39]) and on magnetostratigraphic dating (e.g., [40 -42]). The central part of Crete is presently located at 35.2jN and 25jE.…”

“…The magnetostratigraphic data set is much larger, having 686 sites of good quality directions [41 -43]. The directions have been adjusted for their local block rotation (see [39]) and are shown in Fig. 1.…”

A Late Pleistocene clockwise rotation phase of Zakynthos (Greece) and implications for the evolution of the western Aegean arc

“…Many geophysical modelling studies concerning the Aegean arc have used constraints derived from these palaeomagnetic data [20][21][22]. However, recent results from Crete indicate predominantly post-early Messinian anticlockwise (ac) rotations, in agreement with a tectonostratigraphic analysis [23]. These ac rotations are governed by rotations of fault-bounded blocks.…”

Shallow bias in Mediterranean paleomagnetic directions caused by inclination error

“…This has a corresponding GAD inclination of 54.8j. The main conclusion derived from the declination data was that Crete as a whole did not experience any significant rotation since Tortonian times [17], although many sites showed counterclockwise rotations related to local fault-bounded blocks [39]. The mean direction of the 20 sites (9 reversed and 11 normal) of [17] is D = 358.9j, I = 45.7j.…”