Mineralogy and origin of the carbonate beach sediments of Malta and Gozo, Maltese Islands

Abstract

The contents of aragonite, calcite and rugh-Mg calcite, as well as the content of MgCO, within the calcites were determined by X-ray diffraction analyses in samples of Recent sandy sediments collected on the beaches of Malta and Gozo (Maltese Islands). The comparison of mineralogical data obtained, with the results of the observation at the microscope of both the sediments themselves and the Tertiary rocks (Late Oligocene-Miocene) outcropping in the Maltese Islands, allowed for the following conclusions: 1) The beach sediments are constituted of over 90% carbonates, mostly of organic origin. The prominent mineralogical phase is calcite, with which minor quantities of aragonite and highMg calcite are generally associated. 2) The major part of the calcite derives from erosion of the Tertiary formations. 3) The aragonite can be attributed to Recent mollusk shells. 4) The high-Mg calcite is attributable to Recent porcelaneous foraminifer tests and to red algae and echinoids remains. 5) The MgCO, content in the high-Mg calcite is comparable to that in the Recent carbonate sediments of the Mediterranean area and southern Florida. 6) The carbonate production in the Maltese Islands is presently rather scarce.