تحليل زمين ساخت- رسوبي رسوبات پليو- كواترنري مرتفع دامنه جنوبي ميشوداغ در شمال باختري ايران

Tectono-sedimentary analysis of high-altitude Plio-Quaternary sediments, southern slope of Mishow-Dagh, northwest of Iran

This study investigates the role of tectonic activities in fluvial systems and produce of accommodation space for Plio-Quaternary sediments of Southern slope of Mishow-Dagh horst which is an important structural element within the horst-graben system of north of the Orumia Lake, northwest of Iran. The result of these activities and other environmental and geomorphologic processes has been to impose control mechanisms in quality of sedimentation in sedimentary environments of the study area. Investigations on Plio-Quaternary sediments via interpretation of geological, topographical and areal photos and especially field studies, indicate that several evolution stages are occurred in sedimentary systems in the study area. Based on all constraints, a five stage evolutionary model of deposits as moderately consolidated conglomerate, Qt1, Qt2, Qt3 and Qt4 are proposed and then, the role of tectonic activities assessed on each of them. The results of study showed that present topographic and geomorphologic landscape of study area hardly influenced by Quaternary tectonic activities and this factor was played the main role in produce of accommodation space and formation of transverse drainage network. The record of formation of transverse drainage network referred to after the Pasadanian orogeny and before the beginning of stage Qt1 sedimentation. Since there are not witnesses based on uplift movements in central part of Mishow-Dagh in recent geologic times and especially Quaternary, therefore, it should be look for the reason of the increase in sediment yield of fluvial systems and spread sedimentation in Quaternary, in other factors such as climatic changes. However, geomorphologic witnesses based on fluvial systems properties, indicate that the Orumia Lake bed subsided in Pleistocene and Holocene as the result of Sharafkhaneh fault activities, that probably synchronous to Quaternary climatic changes(?) caused falling of Orumia Lake water surface. In particular, this paper provides a case study that contributes to the understanding of landscape development within tectonically active zones.