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Geoscience e-Journals





An International Year of Planet Earth-2008 Initiative

Current Issue Technical

Year 2020

Volume 13 (3)

Sediment Transport Mechanisms and Tectonic Origin of Quaternary Sediments in Saghalak-Sar Wetland, Rasht, Iran
Masoumeh Mojmeli Renani1, Khalil Rezaei2, Mehran Arian1, Seyed Mohsen Aleali1 and Pantea Giahchi3

The importance of wetlands as unique environments and rich in various elements from an environmental point of view is increasing every day. In this research, the grain size and geochemistry of Quaternary sediments in Saghalak-Sar lagoon, as one of the wetlands in Guilan province, north of Iran, were investigated. For these propose, 74 surface and subsurface samples of the above sediments were collected and analyzed for grain size and finally, frequency of major elements and sub-elements oxides was determined by ICP and XRF, respectively. The granulometery results showed that the sediments can be classified into eight sedimentary classes including slightly gravelly muddy sand, slightly gravelly sandy mud, sandy mud, gravelly muddy sand, gravelly mud, Slightly Gravelly Sandy Mud, and gravelly sand. Surface adsorption of sediment samples are moderate - weak and the tilting in most samples is negative towards negative coarse grains. The frequency of sediment populations in the region is not same so, the mutation population is the most frequent in the majority of the samples. Based on the results of texture analyses, these sediments are probably transmitted to the basins by the river or muddy streams. Also, based on the compatibility of wetland samples on the two-axial diagrams of the main elements oxides, i.e., Fe2O3 + MgO versus Al2O3/ SiO2 and TiO2 and log (K2O / Na2O) versus SiO2, as well as the triangular diagrams of the sub-elements Zr, Th, La, and Sc, it seems that the above sediments are more belong to the range of oceanic arc islands and continental arcs, and are composed of subduction rocks.

Keywords: Wetland,Sediment, Saghalak-Sar, Tectoinic

Neoarchean A-Type Granite in the BundelkhandCraton near Kuraicha: Implications for Crustal Reworking
Mir MdRamiz1, M.E.A. Mondal* and Iftikhar Ahmad

A distinct Neoarchaean granite is identified from the Bundelkhand Craton in Kuraichaarea, Jhansidistrict, Uttar Pradesh.These granites are fine to medium grained,metaluminous to peraluminous in nature,enriched in silica and K, and very low in FeOt+MgO+MnO, Ni, Cr, V concentration. They show pronounced negative Eu-anomaly, HREE enriched patterns and very low Sr/Y ratio. They show A-type characters and plot in the A2 field with high Y/Nb ratio. High ZST of 684-799?C along with increasing Rb/Sr for decreasing Ba concentration in the Kuraicha granites indicate high temperature melting in a fluid absent condition at shallow crustal depths. We propose this A-type granite are the product of high temperature re-melting of older crust and mark the culmination of granite magmatism in the BundelkhandCraton and thus represent a phase of major tectonothermal reworking event during the Neoarchean.


Keywords: BundelkhandCraton, granites, A-type, reworking, Neoarchean