USING GEOCHEMICAL AND GEOSPATIAL ANALYSES TO DETERMINE FOSSIL LOCALITIES OF MOROCCAN TRILOBITES FROM THE DEVONIAN

A major obstacle to paleontological studies is limited data availability. This is made worse if there is no accurate or specific locality and stratigraphic information for a specimen. This is a particular problem for trilobites from Morocco. Nearly all specimens, whether in museums or in private hands, were purchased through the commercial fossil trade, and frequently come with little or vague locality and stratigraphic data. However, specimens show definite differences in the color and texture of the matrix and trilobites themselves. This would suggest there are distinct chemical differences present in the specimens and that these differences may be related to the diagenetic history of geography and stratigraphy. This project is an attempt to find a geochemical basis for locality designation.

Through contacts in the fossil trade, access was obtained to a large collection (329 specimens; 303 with locality data) of unprepared Devonian trilobite specimens from Morocco. At the request of the purchaser, these were collected with, associated locality information in the form of dig site coordinates and preliminary taxonomic identifications provided directly by the Moroccan diggers who collected the specimens. Geochemical data were collected from 329 specimens representing 11 localities using a Thermo Scientific™ Niton™ XL3t X-Ray Fluorescence (XRF) Analyzer to determine the chemical composition of the matrix. The compositions were used to identify trends between fossil localities. Multi-spectral satellite imagery obtained from the European Union’s Copernicus Program was used to georeference geologic maps of Morocco. Using remote sensing and GIS techniques the locality data was plotted on the maps to verify the dig locations.

The resulting maps and geochemical trends confirmed the provided digger information to the geologic units of the Devonian Era. The collected geochemical data revealed distinct differences and trends in the elements Fe, Ca, Si, Rb, and Sr present in the matrix. Specimens of the same locality are similar in composition of elements, while there are differences in elemental composition between localities. Based on the collected data, geochemical and geospatial analyses can identify region and locality and alleviate the lack of locality data associated with Moroccan specimens.