Provenance of sediments from Barra del Tordo and Tesoro beaches, Tamaulipas State, northwestern Gulf of Mexico

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.


Introduction
The geochemistry of beach sediments in the Gulf of Mexico have been studied by various authors (Rosales-Hoz et al. 2015;Machain-Castillo et al. 2019;Ayala-Pérez et al. 2021;Kasper-Zubillaga et al. 2021), whereas the U-Pb ages of detrital zircons from the Gulf of Mexico coastal sediments have not been studied extensively. Nevertheless, U-Pb ages of zircon grains in volcanic rocks from various terranes in Mexico such as Cuicateco, Oaxacan Complex, Xolapa Complex, Mesa Central Province, and Eastern Alkaline Province were widely studied (Solari et al. 2004;Rubio-Cisneros and Lawton 2011;Lawton and Molina-Garza 2014;Juárez-Arriaga et al. 2019;Sieck et al. 2019; Barboza-Gudiño et al. 2020;Torres-Sánchez et al. 2020;Verma et al. 2021).
The mineralogical and geochemical compositions of detrital sediments are commonly used to investigate the provenance, weathering, and tectonic setting of source area (e.g. Cullers et al. 1988;Chaudhuri et al. 2018Chaudhuri et al. , 2020Critelli 2018; Al-Kaaby and Albadran 2020; Banerjee et al. 2020;Rivera-Gómez et al. 2020;Critelli et al. 2021;Karlik et al. 2021). Although detrital sediments are influenced by diagenesis and recycling, their mineral and geochemistry composition is primarily depended on source rocks. The immobile trace elements like REE, Cr, Hf, Nb, Ni, Th, and V are highly reliable indicators to differentiate sediments derived from felsic and/or mafic igneous rocks (Critelli et al. 1997(Critelli et al. , 2003Zeng et al. 2019;Arribas et al. 2000;Cullers 2000). Similarly, chondrite-normalized REE patterns and the Eu anomaly are also extensively utilized in various studies to infer source rock characteristics (e.g. Bankole et al. 2020;Chaudhuri et al. 2020).
Detrital zircon U-Pb age has become a common method to investigate zircon origin and to further discriminate source terranes (e.g. Lee et al. 2015;McRivette et al. 2019;Wang et al. 2020;Armstrong-Altrin et al. 2021). Zircon is a common mineral in acidic rocks, and due to its resistance capacity against weathering and thermal alteration, zircon retains U-Pb isotopic signatures related to their origin and parent rocks (Potter-McIntyre et al. 2018;Dew et al. 2019). Numerous studies proved that detrital zircon U-Pb geochronology is a powerful tool to investigate sediment provenance and their transport pathway (e.g. Gärtner et al. 2017;Hoskin and Ireland 2000;Al-Juboury et al. 2020). Besides, a few studies also documented the importance of the combination of the zircon U-Pb age and sediment geochemistry to infer provenance and to locate source terranes (Turzewski et al. 2020;Zeng et al. 2020).
In this study, the mineralogy, bulk sediment composition, and U-Pb ages of detrital zircons retrieved from the Barra del Tordo and Tesoro beaches, northwestern Gulf of Mexico are analyzed for the aims (1) to investigate the sediment provenance and (2) to identify the source terranes supplying sediments to the beach areas.

Study area and geology
Forty sediment samples (3 kg each) were collected in the Barra del Tordo (23°07′30.78″N-97°45′53.04″W) and Tesoro (22°29′42.39″N-97°51′7.99″W) beaches, located at the Tamaulipas State, the northwestern part of the Gulf of Mexico (Fig. 1). A 1-cm-thick top layer of the beach sand was removed before collecting the samples. Approximately a 100 m interval was maintained between sample locations. Metamorphic rocks from the Precambrian to the Paleozoic, marine sedimentary rocks from the Paleozoic to the Quaternary, igneous rocks of the Cenozoic age, and the unconsolidated Quaternary sediments are outcropped in the Tamaulipas State (Demant and Robin 1975;Rubio-Cisneros and Lawton 2011). The sediments in the coastal plain in the northwestern Gulf of Mexico mainly consist of (1) Mesozoic clastic (sandstone, siltstone, and shale) and calcareous (limestone) sedimentary rocks, and (2) Cenozoic volcanic rocks, which belong to the Sierra Madre Oriental Province (Demant and Robin 1975;Hudson 2003). The Pánuco, Tamesí, and Soto la Marina River drainage basins consist of arid to semi-arid Mesa Central Province, Oaxacan Complex, the north-south trending Sierra Madre Oriental, and the Gulf Coastal Plain.
In summer, longshore surface currents have a northward flow direction with an average velocity of 4.5 cm/s. In winter, longshore surface currents flow towards the south with an average velocity of 6 cm/s. Higher wind velocities were recorded during summer, which vary from 3.0 m/s to 5.4 m/s (Yáñez-Arancibia et al. 2009). Monreal-Gómez et al. (1992) documented that the water circulation and hydrodynamic condition of the Gulf of Mexico are controlled by loop currents and anticyclonic rings. There are "northers" associated with weather conditions of a short time scale (2-3 days) with highpressure system that originates frequently in the Rocky Mountains of the United States and travels from high latitudes to the Gulf of Mexico.

Granulometry
Twenty sediment samples from the Barra del Tordo beach and 20 from the Tesoro beach were air-dried and sieved by a Ro-Tap sieve Shaker using American Standard Test Materials sieves from + 7 to + 270 mesh sizes with 0.50 ϕ interval for 40 min (ϕ being a grade-scale that is inverse of the grain diameter; Wentworth 1922). Cumulative curves were constructed and used to calculate the statistical grain-size parameters (mean size and sorting values) by applying the equations of Folk and Ward (1957). The Ro-Tap sieve Shaker is located at the Sedimentology Laboratory, Instituto de Ciencias del Mar y Limnología (ICML), Universidad Nacional Autónoma de México (UNAM), Mexico City.

SEM-EDS
Sand grain composition was obtained randomly by wave dispersive analyses (WDS) using a JEOL JXA-8900R electron microprobe housed in the Institute of Geophysics, UNAM, Mexico City. Peak counting times were 40 s for each element, except for Na and K with 10 s.

Thin-section petrography
Twenty thin-sections (10 from Tesoro beach and 10 from Tordo beach) were prepared following a common procedure. The modal component was studied based on the Gazzi-Dickinson point counting methodology (Gazzi 1966;Dickinson 1970). Combined organic and inorganic stains specific for iron-rich calcite (Katz and Friedman 1965) were adopted to identify the mineralogical variations.

Sediment composition
Twenty bulk sediment samples (10 from Tesoro beach and 10 from Tordo beach) were powdered by an agate mortar, and the major element concentrations were determined using a Thermo Scientific Niton FXL 950 X-Ray Fluorescence (XRF) analyzer (Balaram 2021). Accuracy of the major element analysis was monitored by an International Standard Gabbro JGB1 (GSJ). The precision of major element data was better than 5%. Loss on ignition was obtained by weighing after combusting 1 h at 1000°C. Similarly, the trace and REE concentrations for 20 sediment samples were determined by a VG Elemental PQII Plus ICP-MS and the operation procedure was similar as the detailed in Jarvis (1988). For data calibration, the United States Geological Survey Standard BCR-2 (Basalt, Columbia River) was used. In general, the analytical precision was less than 5%. Eu and Ce anomalies are calculated as Eu/Eu * = Eu CN /[(Sm CN )·(Gd CN )] 1/2 and Ce/Ce * = Ce CN / [(La CN )·(Pr CN )] 1/2 , respectively ( CN means chondritenormalized values from Taylor and McLennan 1985).

Detrital zircon U-Pb dating
Four hundred zircon grains were analyzed for U-Pb ages, 200 from Tordo beach (sample numbers PBT1 and PBT13) and 200 from Tesoro beach (sample numbers PT1 and PT19). The detrital zircon grains were handpicked under a binocular microscope and then mounted in an epoxy disc. The cathodoluminescence images of detrital zircon grains from the Barra del Tordo and Tesoro beach sediments analyzed in this study are provided in Additional file 1 (Supplementary Information 1 and 2, respectively). Zircon U-Pb geochronology was performed by a Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICPMS) at the Laboratorio de Estudios Isotópicos (LEI), Centro de Geociencias, UNAM. The laser ablation system at LEI consists of a Resonetics M050 workstation, equipped with an LPX 220 excimer laser and an S-155 two-volume cell (Müller et al. 2009;Paton et al. 2010;Petrus and Kamber 2012). The laser workstation is connected to either a Thermo ICap Qcquadrupole ICPMS or a Thermo Neptune Plus multi-collector ICPMS. A "squid" signal homogenizer is used right after the ablation cell before the ablated material enters the plasma. 350 ml of He is used as carrier gas, mixed downstream with 4.5 ml of N 2 . A frequency of 5 Hz was employed, with a fluence of 6 J/cm 2 .
The background average was subtracted from the net intensity measured for each isotope. The acquisition involved an alternation of 2 analyses of Plešovice reference zircon (~337 Ma, Sláma et al. 2008), NIST 610 standard glasses and 5 unknown zircons, using standardunknown bracketing method to allow downhole fractionation corrections to be performed with an inhouse developed software (Solari et al. 2010). Precision on measured ratios of 207 Pb/ 206 Pb, 206 Pb/ 238 U, and 208 Pb/ 232 Th was~0.7% with 1σ relative standard deviation. Replicate analyses of the Plešovice zircon indicate an external reproducibility of 0.8%, 0.7%, and 1.6% on the measured 207 Pb/ 206 Pb, 206 Pb/ 238 U and 208 Pb/ 232 Th ratios, respectively. These errors are quadratically included in the quoted uncertainties for individual analyses of the analyzed zircons. Concordia, probability density plots and cumulative proportion curves were generated from the corrected 207 Pb/ 206 Pb ratios and the integrated concordant and discordant ages through ISOPLOT 3.70 Software (Ludwig 2003). The Tuff-Zirc algorithm combined in the same software was used to calculate the mean 206 Pb/ 238 U ages and their errors, as well as to filter outliers, which are preferred for grains younger than 1000 Ma (Ludwig 1998;Ludwig 2003

Bulk sediment 4.1.1 Textural parameters
The textural parameters for the Barra del Tordo and Tesoro beach sediments are listed in Additional file 2 (Supplementary Information 3). The Tordo beach sediments are predominately medium-grained, moderately sorted, near symmetrical, and very leptokurtic. On the other hand, Tesoro beach sediments are predominantly fine-grained, moderately sorted, near symmetrical, and very leptokurtic.
The REE contents in the Tordo and Tesoro beach sediments are reported in Additional file 2 (Supplementary Information 5). The chondrite-normalized REE patterns of bulk sediments are shown in Fig. 4c, and are more fractionated in the Tordo relative to the Tesoro beach sediments. The REE patterns are with distinct negative europium (Eu/Eu * ) anomaly. The Eu/Eu * ratios for Tordo and Tesoro beach sediments range between0 .50-0.80 and~0.56-0.68 respectively. A significantly positive correlation is observed for ΣREE against TiO 2 ,   Fig. 5b and d), which correspond to the Proterozoic, Mesozoic, and Cenozoic.

Tesoro beach
The zircon U-Pb ages obtained from two samples (PT1 and PT19) are listed in Additional file 2 (Supplementary Information 7). Among 200 analyses, 188 zircons yielded concordant ages (Fig. 6a and c). The probability density plots for samples PT1 and PT19 are shown in Fig. 6b    against Ca, Sr, Rb, Ba, and Zn for Tordo and Tesoro beach sediments and indicates the association of these elements with a similar source. The REE fractionation of Tordo beach sediments is probably due to the effect of weathering.

Sediment weathering and sorting
The chemical composition of detrital sediments is highly useful to interpret sediment recycling and intensity of weathering (Devi et al. 2017 Supplementary Information 4). Hydraulic sorting of sediments can be evaluated by the Index of Compositional Variability (ICV), which decreases when weathering increases (Cox et al. 1995). The ICV values of Tordo beach sediments vary from 0.95 to 2.41, except for two samples PBT1 and PBT7, which show higher values relative to other samples (9.4 and 5.2, respectively). ICV values of Tesoro beach sediments range between 1.61 and 1.78 ( Supplementary Information 4). According to Cox et al. (1995), ICV > 1 indicates littleweathered detrital minerals like feldspar, and ICV < 1 represents fine-grained sediments like clay. In general, ICV values in Tesoro and Tordo beach sediments are larger than 1, indicating the dominance of detrital minerals.

Geochemistry
To infer the provenance of the Barra del Tordo and Tesoro beach sediments, we employed a provenance discrimination diagram based on the major oxides (Roser and Korsch 1988), which is frequently used in various studies (e.g. Tawfik et al. 2018;Bineli et al. 2020;Madhavaraju et al. 2020;Mustafa and Tobia 2020). On this plot, the samples are clustered in the quartzose sedimentary provenance field (Fig. 7), indicating a recycled quartzose provenance. Besides, the TiO 2 /Zr ratio in detrital sediments is one of the best indicators on source rock types (Girty et al. 1996). TiO 2 /Zr ratio values are higher in mafic igneous (> 195) rocks than in intermediate (~55-195) and felsic (< 55) igneous rocks. The TiO 2 /Zr ratios are very low in the Tordo and Tesoro beach sediments (~0.05-0.22 and~0.04-0.09, respectively), indicating their derivation from felsic source rocks.
Trace element concentrations of sediments, particularly immobile elements like La, Sc, Co, Cr, Th, and REE are helpful to predict the nature of source rocks, due to a compositional difference between silicic and mafic rocks (e.g. Anaya-Gregorio et al. 2018;Cullers 2000). Hence, the immobile elements and their elemental ratios are utilized in various studies to differentiate source rocks (e.g. Damian et al. 2019;Hossain 2019;Tobia and Shangola 2019;Patra and Shukla 2020;Ekoa Bessa et al. 2021). La/Sc, La/Co, Th/Sc, and Cr/Th ratios in the Tordo and Tesoro beach sediments are compared with sediments derived from felsic and mafic sources, as well as with average UCC values ( Supplementary Information  8). This comparative study reveals that these sediments were likely derived from felsic source rocks. Furthermore, the relative chondrite-normalized REE pattern and the Eu anomaly have also been used to infer the source of clastic sediments (e.g. Cullers 2000;Hernández-Hinojosa et al. 2018;Kettanah et al. 2021;Madhavaraju et al. 2021). The REE patterns of the Tordo and Tesoro beach sediments are both with a significantly negative Eu anomaly, indicating felsic igneous rocks as their sources (Fig. 4c).

Geochronological evidence
Three major zircon U-Pb age populations are identified in the Barra del Tordo and Tesoro beach sediments Detrital zircon U-Pb dating ages of this study are compared with the detrital zircon ages from potential source terranes of northwestern Mexico (Fig. 8).
The Proterozoic age population in this study is similar to zircon U-Pb ages reported from the Sierra Madre Oriental, Tamaulipas State, which represent the Grenvillian (~1250-920 Ma) and the Pan-African orogen period (~730-530 Ma). Another likely source for the Proterozoic zircons of the Tordo and Tesoro beaches is the Oaxacan Complex, which contains extensive outcrops of the Gren  comparison of zircon ages, it is identified that the Mesa Central Province is the source terrane, which supplied Mesozoic zircons to the beach areas. The Cenozoic age population represents the Eastern Alkaline Province (EAP), which includes various volcanic fields, located in the Gulf of Mexico coastal region . The zircon ages reported from the EAP volcanic fields range from 8.0 Ma to 2.82 Ma. For instance, zircon ages inferred by K-Ar and Ar-Ar dating are ≦9 Ma in the Tlanchinol succession (7.33-2.82 Ma), Sierra Tantima (~9.0 Ma), and Alamo volcanic field (~6.91 Ma) of the EAP (Sieck et al. 2019). Another source for the Cenozoic age zircons is the Mesa Central Province (MCP), which consists of three tectonomagmatic stages (Sieck et al. 2019). First, a long phase of andesitic to dacitic arc volcanism (~45-31 Ma) connected with the subduction of the Farallon Plate that lasted until Eocene-Oligocene. Second is an extension-related phase (~32-25 Ma) overlapped with the Oligocene to Miocene basin. The third stage corresponds to an Early Miocene (~23-20 Ma) mafic magmatism that marked the evolution from a continental arc regime to intraplate volcanism. Hence, the similarity in zircon age populations of this study with EAP and MCP reveals that these provinces are the likely sources for the Cenozoic zircons of the Tordo and Tesoro beaches. Based on the above discussions, it is assumed that the San Fernando, Soto la Marina, Tamesí, and Pánuco Rivers drained along the Sierra Madre Oriental, Mesa Central Province, and Oaxacan Complex carried sediments to the Barra del Tordo and Tesoro beaches and played an important role in defining the sediment source. The probable sediment transport pathway is briefly illustrated in Fig. 9.

Conclusions
The mineralogy, sediment composition, and zircon U-Pb ages were analyzed to identify the sources, which supplied sediments to the Barra del Tordo and Tesoro beaches in the northwestern Gulf of Mexico. The results of this study reveal that the Barra del Tordo and Tesoro beach sediments are mainly composed of quartz, ilmenite, magnetite, zircon, titanite, and anorthite. The weathering indices like CIA, CIW, and PIA indicate a moderate to high intensity of weathering in the source area. The major element concentrations, trace elemental ratios of La/Sc, La/Co, Th/Sc, and Cr/Th, and REE patterns with prominent negative Eu anomaly in the Barra del Tordo and Tesoro beach sediments all indicate a felsic provenance.
Zircon U-Pb dating for the Barra del Tordo and Tesoro beach sediments suggests three dominant age peaks: Proterozoic (~2593-560.4 Ma), Mesozoic (~249.3-68.9 Ma), Cenozoic (~69.9-1.2 Ma). Differences in U-Pb age populations between the Barra del Tordo and Tesoro beach sediments are not significant, suggesting a similar provenance. It is inferred that the Proterozoic zircons in the beach areas were transported from the Grenvillian igneous suites in the Oaxacan Complex as well as from the Sierra Madre Oriental. The potential suppliers for the Mesozoic and Cenozoic age zircons to the beach areas are the Eastern Alkaline and Mesa Central Provinces, among which the Mesa Central Province is the major contributor of sediments to the Barra del Tordo and Tesoro beach areas. Furthermore, the San Fernando, Soto la Marina, Tamesí, and Pánuco Rivers in the northwestern Gulf of Mexico are interpreted to deliver source sediments to the beach areas, which were subsequently mixed by longshore currents. Additional file 2: Supplementary Information 3. Graphic mean grain size (Mz) and textural parameters for the Barra del Tordo and Tesoro beach sediments, northwestern Gulf of Mexico. Grain size classifications were based on Wentworth (1922) and Folk and Ward (1957). Supplementary Information 4. Major element concentrations (in wt.%) in the Barra del Tordo and Tesoro beach sediments, northwestern Gulf of Mexico. Supplementary Information 5. Trace and rare earth element concentrations (in ppm) in the Barra del Tordo and Tesoro beach sediments, northwestern Gulf of Mexico. Supplementary Information 6. U-Pb geochronology data for zircons of samples PBT1 and PBT13 analyzed from the Barra del Tordo beach sediments, northwestern Gulf of Mexico. Supplementary Information 7. U-Pb geochronology data for zircons of samples PT1 and PT19 analyzed from the Tesoro beach sediments, northwestern Gulf of Mexico. Supplementary Information 8. Range of trace elemental ratios in the Barra del Tordo and Tesoro beach sediments, compared with ratio range of sediments derived from felsic and mafic rocks, and the Upper Continental Crust.

Availability of data and materials
All data discussed in this study are available in the current

Competing interests
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

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