Habib Alimohammadian; F Mahdipour Haskouei; J Sabouri
Abstract
The study area is situated at about 8 km away of Neka city, on the main road of Sari-Behshahr, in MazandaranProvince, north of Iran. It is bounded by Alborz fault in the south and Caspian Sea coast line in the north. We applied new environmental magnetism technique and methods including magnetic susceptibility, ...
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The study area is situated at about 8 km away of Neka city, on the main road of Sari-Behshahr, in MazandaranProvince, north of Iran. It is bounded by Alborz fault in the south and Caspian Sea coast line in the north. We applied new environmental magnetism technique and methods including magnetic susceptibility, magnetic mineralogy, IRM and S-IRM to reconstruct the past 50 ka climate conditions and also investigate relationship between climate change and magnetic variations. We also compared the geochemistry and magnetic analysis of the loess/palaeosol deposits and the results were used to correlate these variations with climate change in the study area. The pattern of variation of geochemical data shows similarity with those of magnetic one. The increase/decrease in magnetic susceptibility is coinciding with palaeosol/loess sequences. Plotting magnetic susceptibility variation versus lithological column of Kolet section enabled us to recognize short period of climatically cycles known as stadials/interstadials in loess/palaeosol sequences. We recognized 4 stadials for upper palaeosol, single stadial for lower palaeosol, 6 interstadials for upper loess and one interstadial for lower loess deposites.
M. H. Karimpour; G. L. Farmer; C. R. Stern
Abstract
Biotite-muscovite leucogranite and associated pegmatite intruded meta-ophiolite and meta-flysch (the remnants of Paleo-Tethys) during collision of Turan plate with Iran plate. Four types of pegmatite dykes, crosscutting biotite muscovite leucogranite, are identified. The results of U-Pb zircon ...
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Biotite-muscovite leucogranite and associated pegmatite intruded meta-ophiolite and meta-flysch (the remnants of Paleo-Tethys) during collision of Turan plate with Iran plate. Four types of pegmatite dykes, crosscutting biotite muscovite leucogranite, are identified. The results of U-Pb zircon age of Khajeh Mourad biotite muscovite leucogranite is 205.9 ± 4.1 Ma (Late Triassic, Rhaetian). Chemically, biotite muscovite leucogranite and aplite granite are peraluminous S-type pluton. Magnetic susceptibility of biotite muscovite leucogranite and aplite granite are between than 0-5 × 10-5 and the ratio of ferric to ferrous ratio (< 0.35),therefore they are classified as belonging to the ilmenite-series (reduced type). The total REE content of biotite muscovite leucogranite is between TREE = 130-176 and aplite is very low Total REE = 50.79. They have small negative Eu anomalies (Eu/Eu*= 0.52 to 0.76). The initial 87Sr/86Sr and (143Nd/144Nd)i was recalculated to an age of 205 Ma. Initial 87Sr/86Sr ratios for B-M leucogranite and aplite are 0.708161-0.709853. The (143Nd/144Nd)i isotope composition for B-M leucogranite 0.512214, aplite dykes 0.512024. Initial ε Nd isotope values for B-M leucogranite -6.48 and aplite dykes is -6.83. These values could beconsidered as representative of continental crust-derived magmas. The ratios of Rb/Sr = 1-1.3 and CaO/Na2O » 0.3 of biotite-muscovite leucogranite indicate that the source rock had a composition between meta-pelite and meta-psammite.
