Jayagopal Madhavaraju

This study investigates the textural characteristics, mineral composition, and U–Pb ages of detrital zircon grains from the Playa Norte (PN) and Playa Tamiahua (PT) beach sediments along the Gulf of Mexico (GoM). The objective is to trace the sediment origin and to identify the possible environmental impacts in the coastal ecosystem. This work represents the first integrated provenance and geochemical analysis performed in these beaches, contributing to a broader regional sedimentological and geochronological database for the GoM. The results reveal distinct compositional and provenance signatures: PN sediments are rich in quartz (57.7% avg.), feldspars (15.7% avg.), and carbonate minerals (8.6% avg.), with zircon populations dominated by Proterozoic ages (~820–2200 Ma) and minor anthropogenic enrichment. In contrast, PT exhibits higher contents of quartz (78.6% avg.), andesine (9.6% avg.), and anorthite (8.5% avg.), with zircons mainly of Oligocene age (~32 Ma) and minimal contamination. Comparison with potential source regions indicates that PN sediments were derived primarily from the Sierra Madre Oriental, while PT sediments were originated from the Mesa Central and Eastern Mexican Alkaline Provinces. Overall, the findings demonstrate that, beyond littoral mixing and sediment recycling, the composition of GoM coastal sediments reflects the region’s complex tectono-sedimentary evolution and variable natural versus anthropogenic influences. PN is enriched in arsenic content, which is associated with agricultural activities and oil industries, while PT exhibits low values with no evidence of contamination. Meanwhile, Cr in PN suggests an anthropogenic input, which is linked to oil exploration activities in the GoM.

The Salina Cruz and Puerto Ángel beach areas in the Gulf of Tehuantepec, Mexican Pacific coast represent an important economic sector of the region. In this study, the mineralogy and geochemistry of bulk sediments, and geochronology of 400 detrital zircons recovered from the beach sediments were analysed to investigate their origin. The sediments are abundant in quartz, feldspar, ilmenite, cordierite, aragonite and anorthite. The chemical index of weathering revealed a moderate to intense weathering in the source area. The chondrite normalized REE patterns of bulk sediments are similar to the found in the Upper Continental Crust, suggesting the derivation of sediments from felsic igneous rocks. The REE patterns of zircons and the trace elemental ratios reveal a continental crust origin. Zircon U–Pb ages in the Salina Cruz beach were represented by Proterozoic (~545.1–1314.1 Ma; n = 170) and Cenozoic (~0.01–66 Ma; n = 20). The Puerto Ángel beach was abundant in Proterozoic zircon grains (~600.9–1171.4 Ma; n = 109) and followed by Mesozoic grains (~73.78–246.9 Ma; n = 40). The comparison of zircon U–Pb ages of this study with probable source rocks reveals that the Oaxaquia Terrane and Chiapas Massif Complex were the major contributors of Proterozoic zircons to the coastal areas. Similarly, the results indicate that the Cenozoic zircons were contributed by the Chiapas Massif Complex, coastal batholith and Cuicateco Terrane. The Mesozoic zircons are very few, derived from the nearby Xolapa Complex and the Chuacús Terrane.