ORIGINAL ARTICLE Sedimentological and geoenvironmental evaluation of the coastal area between Al-Khowkhah and Al-Mokha, southeastern Red Sea, Republic of Yemen Ahmed R. El-Younsy 1 • Mahmoud A. Essa 1 • Saeed O. Wasel 2 Received: 17 January 2016 / Accepted: 2 December 2016 Ó Springer-Verlag Berlin Heidelberg 2016 Abstract The increasing anthropogenic activities (e.g., constructing touristic resorts) have led to notable changes in the Yemeni Red Sea coastal regions. In this context, recent sediments have been investigated to infer possible natural and man-induced processes on these coastal areas. The target area lies between longi- tudes 43°13 0 –43°30 0 E and latitudes 13°15 0 –13°55 0 N. It extends about 90 km along the coastline as a part of the Tihama plain. Geomorphologically, it forms a long- curved stretch with pronounced headlands, embayments and bays. Generally, it is covered by recent sediments (wadi, lagoon, beach and spit deposits along with sab- kha, coastal dunes and mangrove). Textural studies reveal that most of the studied sediments are mainly poorly to moderately sorted and are composed mainly of sandy fractions with few gravel and mud, mostly bimodal with minor unimodal patterns. The igneous (granites) as well as basic (basalt, andesite and andesitic pyroclastics) and acidic (dacite and rhyolite) volcanic rocks of Tertiary age, which are exposed to the east of the study area, are believed to be the source of pyrox- enes, amphiboles, epidotes, biotite, sphene, zircon, tourmaline and rutile, in a decreasing order of abun- dance. Moreover, smectite, kaolinite, chlorite, illite and palygorskite are the predominant clay minerals, mainly of detrital origin. The total carbonate content fluctuates from 37.41% (lagoon sediments) to 53.74% (sabkha sediments). The high amount of sea grasses, which covers the tidal flat zone and relates to the fine-grained sediments, accounts for the high organic matter content. The mineralogy of the source rocks has controlled the general distribution of major elements (Fe, Mg, Na, K and Mn) in the beach sediments. In such sediments, the concentrations of the heavy metals (Cu, Zn, Cd, Ni, Pb and Co) may reflect the sediment pollution using dif- ferent approaches. The enrichment factors (EFs) of the trace metals for most samples reveal values that are greater than 1, referring to three groupings, which are: moderate to moderately severe (Zn, Cu and Mn), minor to moderate (Pb and Co) and zero to minor (Cd and Ni) enrichment. The EFs for Pb, Cd, Ni and Co metals ( \ 5) may be attributed to the crustal materials and/or natural weathering processes. But, those for Zn, Cu and Mn ( [ 5), especially in Al-Khowkhah–Abu-Zahr, Moushij– Zahari–Ruays, Yokhtol and Mokha localities, are possi- ble of anthropogenic contributions. Keywords Yemen Á Sedimentology Á Tihama plain Á Pollution Á Mineralogy Á Geochemistry Introduction Several studies have linked the sedimentological, miner- alogical, geochemical and geoenvironmental data on recent sediments to characterize and evaluate the evolution of a coastal area (Al-Edressi 2002; Zhang and Liu 2002; Birch 2003; Pekey et al. 2004; Al-Dughiem 2005; Zhang et al. 2007; Zubair et al. 2014; Reddad et al. 2016). The Republic of Yemen is located in the southern part of the Arabian Peninsula between latitudes 12°–20°N and & Mahmoud A. Essa maessa2002@yahoo.com 1 Department of Geology, Faculty of Science, Assiut University, Assiut 71516, Egypt 2 Department of Marine Geology, Faculty of Marine Sciences and Environments, Hodeidah University, Al Hudaydah, Yemen 123 Environ Earth Sci (2017) 76:50 DOI 10.1007/s12665-016-6355-1