Implication of sedimentology and climatic data for recognition of dust origin, a case study: Khour and Biabanak area (Isfahan province)

Possible sources of the dusts in the Khour and Biabanak were been investigated. For these purposes, 28 surface samples from this area were collected for sedimentology and mineralogy studies. Most of the surficial sediments of the area are fine sand, a few samples with silt and clay size; which are susceptible to wind erosion. Furthermore, climatology could facilitate a better understanding of natural hazards such as dust events. Climatic data for a period of 20 years (1991-2010) including rainfall, dust events, wind speed and directions obtained from Meteorological Organization of Iran were analyzed. Major wind directions are W and NE. Heavy minerals including pyroxene, biotite, amphibole, as well as some opaque minerals are recognized in these sediments, among which the pyroxene is more frequent than the others (1-1.2% av. in whole samples and up to 5-10% in heavy mineral fraction). Most of the pyroxene is augite. According to climatic conditions, overwhelming fine grain sediment particle size (less than 63 µ) of the area and predominant wind direction, the dusts might originate from west of the Khour and Biabanak. Detailed knowledge of dust provenance could aim to eliminate its environmental impacts. Hence, possible sources of dusts were examined. Majority of the sediment cover in the NE of Isfahan provenance are originated from acidic, intermediate and ultramafic rocks exposed in the Anarak area; altered ultramafic rocks of Proterozoic to early Palaeozoic in the Anarak-Khour; as well as ophiolites exposed along major faults such as Naein-Dehshir-Baft.