Stratigraphic Correlation by Integrating Photostratigraphy and Remote Sensing Multispectral Data: An Example from Jurassic-Eocene Strata, Northern Somalia

Abstract

Integrated analyses of aerial photographs and multispectral remote sensing images were used for stratigraphic correlation in mainly carbonate and evaporitic rocks. These rocks crop out in an area of northern Somalia characterized by an arid climate. By the aerial photo analysis, we recognized photostratigraphic logs and stratal patterns and established correlations based on the tracing of physical surfaces with chronostratigraphic significance, such as photohorizons and photostratigraphic discontinuities. A limited number of field sections provided the lithological interpretation of the packages of strata delineated in aerial photos. By satellite multispectral (Landsat Thematic MapperTM) data analysis we identified image facies that represent packages of strata with different lithological characteristics. To interpret the image facies, we compared the responses in the thematic mapper (TM) bands with the laboratory spectroscopic properties of rock samples from the study area, and interpreted the absorption features by p trographic analysis. The Mesozoic and Tertiary strata analyzed herein are part of several formations deposited on a passive margin preceding the Oligocene-Miocene Gulf of Aden rifting and initial drifting. Following this approach, a number of stratigraphic units were recognized and mapped on aerial photos, and a framework of photostratigraphic correlation surfaces was delineated over significantly wide areas. These surfaces approximate time surfaces and are traced both within and across the lithostratigraphic units, improving existing maps. This method represents a mapping tool preliminary to more detailed field work, and is particularly useful in areas of difficult access.