Submission Type
Poster
Abstract
Trilobites are an extinct group of arthropods made up of three distinct body parts produced by calcite that disarticulate after molting. Trilobites lived in shallow, tropical, marine environments and left an excellent fossil record. The Cambrian is known as the age of trilobites, with the greatest diversity of trilobite forms. However, trilobites went extinct at the end of the Permian. The Carrara Formation (lower Cambrian) in Emigrant Pass, Mojave Desert, CA hosted a wide range of trilobite fossils. The area contains moderately deformed and metamorphosed siliciclastic and carbonate rocks from the lower Carrara. Trilobite samples were examined using a Zeiss Stereo microscope and identified based on their morphology. The samples were mostly incomplete with the cephalon as the most common segment found. The cephalon of the trilobites have been mildly sheared as a result of tectonic uplift and tilt making some of them difficult to identify. After examining the various traits within the Trilobite samples, we have concluded they are part of the Olenellidae family. Trilobite samples were also crushed to examine the bulk composition and mineralogy found within them by using tools like scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), and x-ray diffraction (XRD). Trilobites displayed variable preservation of molds, minor original hard parts, and replacement exhibiting a red coating. XRD bulk analysis revealed a bulk mineral composition of quartz, Fe +2 bearing clinochlore, and Fe +3 bearing muscovite. Furthermore, SEM and EDS analysis revealed the red coating to be iron oxide, with traces of calcite and chlorite.
Recommended Citation
Torres Lopez, Reydaliz, "028-Taxonomy and Preservation of Lower Cambrian Trilobites, Carrara Formation, Southern CA" (2024). GREAT Day Posters. 9.
https://knightscholar.geneseo.edu/great-day-symposium/great-day-2024/posters-2024/9
028-Taxonomy and Preservation of Lower Cambrian Trilobites, Carrara Formation, Southern CA
Trilobites are an extinct group of arthropods made up of three distinct body parts produced by calcite that disarticulate after molting. Trilobites lived in shallow, tropical, marine environments and left an excellent fossil record. The Cambrian is known as the age of trilobites, with the greatest diversity of trilobite forms. However, trilobites went extinct at the end of the Permian. The Carrara Formation (lower Cambrian) in Emigrant Pass, Mojave Desert, CA hosted a wide range of trilobite fossils. The area contains moderately deformed and metamorphosed siliciclastic and carbonate rocks from the lower Carrara. Trilobite samples were examined using a Zeiss Stereo microscope and identified based on their morphology. The samples were mostly incomplete with the cephalon as the most common segment found. The cephalon of the trilobites have been mildly sheared as a result of tectonic uplift and tilt making some of them difficult to identify. After examining the various traits within the Trilobite samples, we have concluded they are part of the Olenellidae family. Trilobite samples were also crushed to examine the bulk composition and mineralogy found within them by using tools like scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), and x-ray diffraction (XRD). Trilobites displayed variable preservation of molds, minor original hard parts, and replacement exhibiting a red coating. XRD bulk analysis revealed a bulk mineral composition of quartz, Fe +2 bearing clinochlore, and Fe +3 bearing muscovite. Furthermore, SEM and EDS analysis revealed the red coating to be iron oxide, with traces of calcite and chlorite.