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The mineralogy, bulk sediment geochemical composition, and U–Pb ages of detrital zircons retrieved from the Barra del Tordo (Tordo) and Tesoro beach sediments in the northwestern Gulf of Mexico were analyzed to determine their provenance. The beach sediments are mainly composed of quartz, ilmenite, magnetite, titanite, zircon, and anorthite. The weathering proxies such as the Chemical Index of Alteration (CIA), Chemical Index of Weathering (CIW), and Plagioclase Index of Alteration (PIA), reveal a moderate-to-high intensity of weathering in the source area. The chondrite-normalized rare earth element (REE) patterns are similar to felsic igneous rocks, with large negative europium anomaly (Eu/Eu* = ~ 0.47–0.80 and ~ 0.57–0.67 in the Tordo and Tesoro beach sediments, respectively).Three major zircon U–Pb age groups are identified in the Tordo and Tesoro beach sediments, i.e., Proterozoic (~ 2039–595 Ma), Mesozoic (~ 244–70.3 Ma), and Cenozoic (~ 65.9–1.2 Ma). The differences of the zircon age spectrum between the Tordo and Tesoro beach sediments are not significant. The comparison of zircon U–Pb ages in this study with ages of potential source terranes suggests that the Mesozoic and Cenozoic zircons of the studied Tordo and Tesoro beach sediments were derived from the Eastern Alkaline Province (EAP) and Mesa Central Province (MCP). Similarly, the likely sources for the Proterozoic zircons were the Sierra Madre Oriental (SMOr) and Oaxaquia in the northwestern Gulf of Mexico. The results of this study further indicate that the sediments delivered to the beaches by rivers and redistributed by longshore currents were crucial in determining the sediment provenance.

In this study, we analyzed the mineralogy and bulk chemical composition of 20 sediment samples, as well as trace, rare earth element (REE) concentrations and U–Pb ages of 400 detrital zircons retrieved from the Bosque (PB) and Paseo del Mar (PM) coastal sediments, southwestern Gulf of Mexico, to investigate the provenance. The XRD study revealed that the PB sediments are associated with quartz, muscovite, cordierite, albite, and anorthite. The PM sediments are associated with calcite, aragonite, and biogenic materials, which derived probably within the coastal environment. The weathering indices like Chemical Index of Alteration (CIA), Chemical Index of Weathering (CIW), and Plagioclase Index of Alteration (PIA) revealed a moderate intensity of weathering for the PB sediments. The chondrite normalized REE patterns of the PB and PM sediments are with negative and positive europium anomalies (Eu/Eu*), suggesting that the sediments were derived by the combination of felsic and mafic source rocks. The Th/U ratios (>0.3) of the PB and PM zircons indicated an igneous origin. The chondrite normalized REE patterns of the PB and PM zircons are depleted in low REE (LREE) and enriched in heavy REE (HREE) with positive cerium and negative europium anomalies. A wide variation in chondrite normalized REE patterns of zircons with respect to ages was observed. The PB is dominated by Proterozoic (~551–2500 Ma) and Paleozoic zircons (~445–480 Ma; Ordovician), whereas PM is dominated by Cenozoic zircons (~5–21 Ma; Miocene), indicating that the zircons were derived from different source terranes. The Chiapas Massif (CMC) and Chuacus complexes are identified as the potential source areas, which contributed Proterozoic zircons to PB. On the other hand, Cuicateco terrane (CUI) and Tuxtla Volcanic Field (TVF) are considered as the potential source areas, which supplied significant number of Cenozoic zircons to the PM coastal area. The zircon U–Pb ages and the bulk sediment geochemistry together indicate that the source terranes, which supplied sediments to the PB and PM coastal areas, consist of mafic and felsic rocks. The results of this study further illustrated the importance of littoral currents in distributing sediments, although rivers are considered as a carrier and agent of distributing sediments along the coastal areas.

Surface features of quartz and zircon grains in the Barra del Tordo (PBT) and Tesoro (PT) beaches, NW Gulf of Mexico (GoM), were analyzed. The microtextures in the PBT and PT beaches were classified into mechanical, chemical, and mechanical/chemical origin. The quartz grains from the two beach areas were subrounded to rounded in shape. Rounded zircon grains in PT suggest that the sediments were derived by wind, long transport distance, and long residence time relative to PBT. Rounded quartz grains with the combination of bulbous and broken edges indicated a recycled provenance. Mechanical features such as V-shaped marks, impact scars, conchoidal fractures, and straight-curved grooves indicated a fluvial environment. Chemical features such as solution pits, crystal overgrowth, and adhering particles in quartz and zircon grains indicated a diagenetic environment and silica re-precipitation in a coastal environment. The association of mechanical (bulbous edge) and chemical (silica overgrowth, small and large solution pits) features in a single grain suggested a dual environment, that is, the combination of littoral and coastal environments. The sediments were also partly supplied by the coastal dunes located along the GoM coastal region and were redistributed by wave energy and littoral currents. Euhedral, subhedral, and unetched zircon grains in PBT and PT were mixed with rounded and etched grains, indicating a diverse provenance from crystalline rocks. In general, the microtextures identified on zircon and quartz grains reveal that sediments are influenced by wind, fluvial, and subaqueous marine environment and derived by nearby and distal sources.

Microtextures of quartz and zircon grains from the Bosque and Paseo del Mar beaches in the Gulf of Mexico were examined using a Scanning Electron Microscopy (SEM), to infer their provenance and palaeoenvironment. A total of 16 microtextures from 200 grains were identified and were grouped into mechanical, chemical, and mechanical/chemical origin. Microtextures of mechanical origin represent parallel striations (ps), cracks due to collision (ck), conchoidal fractures (cf), v-shaped marks (vs), abrasion fatigue (af), meandering ridges (mr), chattermarks (ch), curved (cg) and straight grooves (sg), which are attributed to a high-energy fluvial and sub-aqueous marine environment. Solution pits (sp), crystal overgrowth (cro), and silica globules (sgl) of chemical origin indicated precipitation and dissolution in a silica saturated marine environment. Adhered particles (ap), elongated depressions (dp), and relief are grouped as mechanical/chemical origin, suggested a sub-aqueous nearshore marine environment. Although zircon is considered as a resistant mineral, the frequency of microtextures observed was higher in zircon than in quartz. The results of this study revealed that the Los Tuxtlas volcanic field, Chiapas Massif and Oaxacan Complexes in the SW Gulf of Mexico are the potential source areas, which supplied sediments to the Paseo del Mar and Bosque beach areas.

Microtextures on fine to medium-grained quartz grains (65–500 μm) from three sections, i.e., Laboni, Kuakata, and Jhauban points of the Kuakata beach area, Bangladesh, were examined by a scanning electron microscope (SEM) to determine the transport history, provenance, depositional environment, and paleoclimate. Thirty microtextures were observed on 180 quartz grains, which were subsequently classified as mechanical (20 features), chemical (5 features), and combined mechanical and chemical (5 features) origins. The abundance of sub-rounded to rounded quartz grains with smooth outlines, V-shaped pits, straight or curved grooves, crescent-shaped features and straight or arcuate steps, indicates that the quartz grains experienced long-distance transport through fluvial environment (e.g., Himalayan sediments). The angular to sub-angular quartz grains with straight or curved grooves, straight steps, and adhering particles inferred that they were probably derived from adjacent landmasses (e.g., Chittagong-Tripura Folded Belt and/or Indo-Burman Ranges). The well-rounded outlines, low relief with dish-shaped depressions, mechanically upturned plates, and arcuate steps were also observed, indicating aeolian processes in shoreface or beach environment. Etching, solution/irregular pits, and differential relief observed in the quartz grains indicate a subaqueous collision in fluvial and nearshore environments.

Foraminifera species distribution, 14C ages, and geochemistry data of sediment cores GM33 and GM34 recovered from the southwestern Gulf of Mexico were investigated to infer the age, sedimentation rate, provenance, heavy metal contamination, and depositional environment. Core GM34 (490 cm interval) reached an age of 34,346 ± 280 cal Yrs. BP and the average sedimentation rate was calculated as 0.014 cm/yr. The weathering indices like Chemical Index of Alteration (CIA), Chemical Index of Weathering (CIW), and Plagioclase Index of Alteration (PIA) revealed a moderate intensity of weathering in the source area. The trace elemental ratios and rare earth element (REE) patterns indicated the derivation of sediments from intermediate rocks like andesite. The trace element based bivariate (La/Sc and Co/Th) and ternary (Ni Th V) diagrams revealed that the sediments were derived mostly from andesite located along the Gulf of Mexico coastal areas. The enrichment factor and geo-accumulation index suggested the absence of heavy metal contamination in sediment cores. The redox proxy trace elemental ratios like V/Cr, Ni/Co, Cu/Zn, and (Cu + Mo)Zn suggested an oxic depositional condition. The benthic foraminiferal assemblages, Mn and Mo concentrations indicated that the late Pleistocene abyssal waters in the Gulf of Mexico were more oxygenated than the present. An absence of significant compositional variations between the core sediments revealed that the depositional condition in the southwestern Gulf of Mexico was probably similar for the last 34,346 cal Yrs. BP.

Mineralogic and geochemical studies were performed in the Tecolutla and Coatzacoalcos beach sediments, located at the SW Gulf of Mexico. The main concern of this article is to infer the weathering, provenance, and degree in which trace metal pollution affects the beach sediment composition. The chemical index of weathering (CIX) for the Tecolutla and Coatzacoalcos beach sediments indicate a moderate intensity of weathering in the source area. The SiO2/Al2O3 ratio values (>6) in the Tecolutla and Coatzacoalcos sediments suggested a high compositional maturity and recycling. A difference in the Al2O3/TiO2 ratios between the Tecolutla and Coatzacoalcos beach sediments points out that the sediments were derived from intermediate and felsic igneous rocks, respectively. A negative correlation for Al2O3 against TiO2 and P2O5, and trace elements Y, Nb, V, Sc, and Cr for the beach sediments suggests an association of these elements with detrital minerals rather than aluminosilicates. The provenance discrimination based on major element concentrations indicates an intermediate and a felsic provenance for the Tecolutla and Coatzacoalcos sediments. The major and trace element geochemistry of beach sediments are associated with a passive margin setting. The Enrichment factor (EF) and Geo accumulation index (Igeo) values show that the Tecolutla sediments are moderately enriched by Cu (EF ∼ 10–17) and Cr (1

Coastal margins, especially the river-influenced coastal areas, are considered as active interfaces between the continental and oceanic environments, which have huge dispersal of detrital materials and heavy metal input. It is well determined that the fine-grained sediments are important reservoir for the accumulation of heavy metals. In this study, we analyzed the radiocarbon age, texture, organic matter, carbonate content, and geochemical compositions of two sediment cores (GM42 and GM44) retrieved in front of the Coatzacoalcos River mouth basin, southwestern Gulf of Mexico (∼864 and 845 m water depth, respectively). Our objective was to infer the sedimentation rate, intensity of weathering, provenance, and influence of anthropogenic activities on heavy metal contamination in sediments. The radiocarbon-age measurements of mixed planktonic foraminifera for core GM44 reveals an age of 21,289 ± 136 cal. years B.P., which fall within the Late Glacial Maximum (LGM; 21000 ± 2000 years B.P). The calculated sedimentation rate for core GM42 (~0.013 cm/year) is lower than in core GM44 (0.022 cm/year), which is probably due to the variations in detrital sediment input and/or seafloor topography. The weathering indices such as chemical index of alteration (CIA), chemical index of weathering (CIW), and plagioclase index of alteration (PIA) suggested that the source area experienced low to moderate intensity of chemical weathering under warm to humid climatic conditions. The SiO2/Al2O3, Al2O3/Na2O, and K2O/Al2O3 ratio values indicated moderate to high compositional maturity. The major and trace element concentrations suggested that the sediments were likely derived from intermediate source rocks. The heavy metal contents indicated that the sediments were not contaminated by the industrial waste disposals supplied by the Coatzacoalcos River. The redox proxy sensitive elements such as V, Cr, Cu, and Zn indicated an oxic depositional environment for the deep-sea sediment cores. The application of discrimination diagrams for the geochemistry data revealed a passive margin setting for the sediment cores. The compositional variations observed at the upper sections (