Geology and Permian paleomagnetism of the Merano region, province of Bolzano, n. Italy

摘要: Geology Stratigraphically, the facies of permo-triassic deposits Merano area is closely connected with that Southern Dolomites. Structurally, region belongs to southern flank east-alpine geanticline. The part alpine geanticline cut in by a major fault southwest-northeast trend, called Judicaria (fig. 2, p. 15). In former syntheses structure Eastern Alps, has generally been considered as sinistral transcurrent or wrench fault. This was assumed have displaced suture line between northern branch sensu stricto and dinaric Alpine Mountain System (sensu largo). net slip Insubric Tonale west Pusteria-Drau east would then be about 80 km. However, analysis minor tectonic features do not confirm this concept. On account outcrop its present character steep upthrust northwestern dip 27, sections I,ll, VI, VII IX, 38). according encountered close fault, originally normal southeastern 28, subphase b, 41). vertical component displacement amounts 5-9 km near town Merano. formation facilitated diapiric ascent tonalitic magma, causing emplacement massifs Monte Croce, Ivigna, Bressanone c). These plutonic masses belong peri-adriatic series tonalites, which most probably, intruded during mid-tertiary insubric phase orogenesis. During intrusion bodies upper dip, probably because magma-tectonic mass-circuit geological data fit van Bemmelen's concept structural evolution (van Bemmelen, 1957, 1960-b, 1960-c). Paleomagnetism A study made paleomagnetic properties permian quartz-porphyries occurring at margin Bolzano volcanic province. Progressive partial demagnetization experiments on orientated samples, means alternating magnetic fields indicate remanent magnetization composed two components, namely relatively unstable component, stable component. represents original acquired upon cooling volcanics. resulted from induction postpermian fields. secondary components can removed exposing samples procedure "cleaning" greatly reduces scatter primary directions magnetization. south pole position deduced average direction (declination 164°, inclination -7,5°) 1460 Wand 45° N. Though latitude agreement poles inferred other rocks european continent, longitude deviates appreciably position, 40° 42, 53). following possibilities for cause above mentioned deviation may suggested: divergence north italian might result secular variation; but also geotectonic possible, instance counter-clockwise rotation around axis