COUNTER-CLOCKWISE ROTATIONS IN THE SOUTHERN APENNINES DURING THE PLEISTOCENE - PALEOMAGNETIC EVIDENCE FROM THE MATERA AREA

被引:43
作者
SCHEEPERS, PJJ [1 ]
LANGEREIS, CG [1 ]
HILGEN, FJ [1 ]
机构
[1] INST EARTH SCI,DEPT GEOL,3584 CD UTRECHT,NETHERLANDS
关键词
D O I
10.1016/0040-1951(93)90306-5
中图分类号
P3 [地球物理学]; P59 [地球化学];
学科分类号
0708 ; 070902 ;
摘要
Sediments from late Pliocene to early Pleistocene age have been sampled at six different localities/sections (38 sites) in the Matera area which is in the southern part of peninsular Italy (Basilicata). Three of the localities are from the Apenninic belt, the other three from the Bradano Unit, both of them west of the earlier sampled Apulian Unit. Stepwise thermal demagnetisation revealed that usually two important components contribute to the natural remanent magnetisation (NRM) of these clay sediments: a low-temperature (LT) component removed between 100 and 300-320 degrees C and a high-temperature (HT) component removed between 300-320 and 430-450 degrees C. The HT component is a characteristic remanent magnetisation (ChRM) for the sediments and has a clear primary (= pre-folding) origin. In fresh, unweathered sediments the LT component is identical in direction to the HT component, but there is evidence that moderate weathering replaced a high-intensity primary LT component with a low-intensity secondary LT magnetisation. The HT magnetisation is affected by this weathering process in a decrease of its intensity. A counter-clockwise deflection in declination is observed for the sites sampled in the Apenninic belt. The HT directions reveal a 23 degrees counter-clockwise rotation relative to the magnetic north: D-m = 336.6 degrees and I-m= 57.2 degrees. Sites in the Bradano Unit have no tectonic rotation: D-m = 359.1 degrees and I-m = 56.3 degrees. Earlier sampled sites from the Apulian Unit also showed no tectonic rotation: D-m = 359.4 degrees and I-m = 57.0 degrees. Paleomagnetic data support the hypothesis that the southern Apennines rotated in the middle-late Pleistocene, after the major phase of extension in the southern part of the Tyrrhenian basin and contemporaneous with a regional compressional phase.
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页码:379 / 410
页数:32
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