The major Quaternary faults of Marzanabad in the north Alborz can be classified based on their strikes into two sets: northwest and eastwest. In this paper, we use a model to evaluate their movement potential. Their t...The major Quaternary faults of Marzanabad in the north Alborz can be classified based on their strikes into two sets: northwest and eastwest. In this paper, we use a model to evaluate their movement potential. Their theoretical model is based on the relationship between fault geometrical characteristics and regional tectonic stress field. The results show that Taleqan, Kandovan Chitan-Dozbon and Makaroud-Dalir fault zones are of the highest movement potential in the area. Also, the region where the fault zones have been intersected (northeastern part of study area) is prone to high seismicity;however, these fault zones don’t have high movement potentials.展开更多
The alkali-basalt and basaltic trachy-andesites volcanic rocks of south Marzanabad were erupted during Cretaceous in central Alborz, which is regarded as the northern part of the Alpine-Himalayan orogenic belt. Based ...The alkali-basalt and basaltic trachy-andesites volcanic rocks of south Marzanabad were erupted during Cretaceous in central Alborz, which is regarded as the northern part of the Alpine-Himalayan orogenic belt. Based on petrography and geochemistry, en route fractional crystallization of ascending magma was an important process in the evolution of the volcanic rocks. Geochemical characteristics imply that the south Marzanabad alkaline basaltic magma was originated from the asthenospheric mantle source, whereas the high ratios of （La/Yb）N and （Dy/Yb）N are related to the low degree of partial melting from the garnet bearing mantle source. Enrichment pattern of Nb and depletion of Rb, K and Y, are similar to the OIB pattern and intraplate alkaline magmatic rocks. The K/Nb and Zr/Nb ratios of volcanic rocks range from 62 to 588 and from 4.27 to 9 respectively, that are some higher in more evolved samples which may reflect minor crustal contamination. The isotopic ratios of Sr and Nd respectively vary from 0.70370 to 0.704387 and from 0.51266 to 0.51281 that suggest the depleted mantle as a magma source. The development of south Marzanabad volcanic rocks could be related to the presence of extensional phase, upwelling and decompressional melting of asthenospheric mantle in the rift basin which made the alkaline magmatism in Cretaceous, in northern central Alborz of lran.展开更多
文摘The major Quaternary faults of Marzanabad in the north Alborz can be classified based on their strikes into two sets: northwest and eastwest. In this paper, we use a model to evaluate their movement potential. Their theoretical model is based on the relationship between fault geometrical characteristics and regional tectonic stress field. The results show that Taleqan, Kandovan Chitan-Dozbon and Makaroud-Dalir fault zones are of the highest movement potential in the area. Also, the region where the fault zones have been intersected (northeastern part of study area) is prone to high seismicity;however, these fault zones don’t have high movement potentials.
基金Dr.Luigi Beccaluva and Dr.Renzo Tassinari University of Ferrara,Italy,for their financial support and providing laboratory facilities
文摘The alkali-basalt and basaltic trachy-andesites volcanic rocks of south Marzanabad were erupted during Cretaceous in central Alborz, which is regarded as the northern part of the Alpine-Himalayan orogenic belt. Based on petrography and geochemistry, en route fractional crystallization of ascending magma was an important process in the evolution of the volcanic rocks. Geochemical characteristics imply that the south Marzanabad alkaline basaltic magma was originated from the asthenospheric mantle source, whereas the high ratios of （La/Yb）N and （Dy/Yb）N are related to the low degree of partial melting from the garnet bearing mantle source. Enrichment pattern of Nb and depletion of Rb, K and Y, are similar to the OIB pattern and intraplate alkaline magmatic rocks. The K/Nb and Zr/Nb ratios of volcanic rocks range from 62 to 588 and from 4.27 to 9 respectively, that are some higher in more evolved samples which may reflect minor crustal contamination. The isotopic ratios of Sr and Nd respectively vary from 0.70370 to 0.704387 and from 0.51266 to 0.51281 that suggest the depleted mantle as a magma source. The development of south Marzanabad volcanic rocks could be related to the presence of extensional phase, upwelling and decompressional melting of asthenospheric mantle in the rift basin which made the alkaline magmatism in Cretaceous, in northern central Alborz of lran.
