Distribution and Significances of the Major Oxides in Recent Coastal Sabkha Sediments of the Al-Dafna Plateau, Northeast Tobruk, Libya

Ahmed Mohamme

doi:10.37375/sjfssu.v1i2.82

Abstract

Twenty sabkha samples were chemically analyzed by XRF technique for determination of their major oxides concentrations. Six cores penetrated both the intertidal and supratidal flat zones developed in six wadis mouths in the coastal stretch of the Al-Dafna plateau, northeast Tobruk city. The significance distribution and concentration of the major oxides are discussed and interpreted. Elements in the raw material of the study area reflect important evidence of geochemical weathering processes that affecting parent rocks as well as conditions of sedimentation, and rate of deposition. Correlation coefficients have been used to illustrate the abundance and distribution of these elements. The distribution of major oxides are follows Si2O > CaO > LOI > Al2O3 > SO3 > MgO > Na2O > K2O. The vertical distribution of major elements is mainly controlled by the abundance and proportions of the clastics, carbonates and evaporite minerals. It was found that silica present in the form of detrital, subrounded to rounded silt- to sand-sized quartz grains, while the content of Al2O3 is associated with terrigenous argillaceous materials. On the other hand, the presence of Fe2O3 is related to the abundance of clastic materials in sabkha deposits. It was found that K2O and Na2O concentrations increase toward the sabkha surfaces.

Highlights

Sabkhas are widespread geomorphological features in the coastal landforms of the Mediterranean Sea of Libya Wadis sabkhas always subjected to flash floods during the rainy season in the main Wadis and/or recharge from tidal flow
The chemical composition of the sabkha deposits provide important information in order to define and understand the basic processes involved in major elements transport during and after the deposition of the sabkha deposits
ClChlorine concentration in the studied intertidal sabkha varies between 0.897 % and 6.39 % with an average value of 2.25 % (Table 1 and Figure 2), whereas the content in the supratidal sabkha ranges from 0.52 % to 5.36 % and its average value is 2.72 % (Table 2 and Figure 3)

Summary

Introduction

Sabkhas are widespread geomorphological features in the coastal landforms of the Mediterranean Sea of Libya Wadis sabkhas always subjected to flash floods during the rainy season in the main Wadis and/or recharge from tidal flow. An attempt has been made to study the geochemical features regarding both abundance and vertical distribution of major elements in the raw sabkha samples of intertidal and supratidal zones. XRF is a well-established analytical technique used for estimating the chemical composition of rocks and sediments both in the field and the laboratory (Potts et al, 1997). XRF is a well-established analytical technique used for estimating the chemical composition of rocks and sediments both in the field and the laboratory (Potts et al, 1997; Ramsey et al, 1995). Wavelengths make it possible to detect which elements are present in the samples. Percentages of silica (SiO2), alumina (Al2O3), ferric oxide (Fe2O3), lime (CaO), magnesium oxide (MgO), sulfur trioxide (SO3), sodium oxide (Na2O), potassium oxide (K2O) chloride content (Cl-) and loss on ignition (LOI) were determined

Study area

Results

Discussion

Conclusion