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- Lower to middle miocene multiproxy biostratigraphy of the P-18 core-stratigraphic well in Sinú-San Jacinto Basin, Caribbean region of ColombiaPublication . Duque-Castaño, Monica; Trejos-Tamayo, Raúl; Osorio-Tabares, Lina Constanza; Angulo-Pardo, Estefanía; Vallejo, Felipe; Plata, Angelo; Pardo-Trujillo, AndrésA Lower-to-Middle Miocene core-stratigraphic section, P-18 well, was drilled in the Sinu-San Jacinto Basin (SSJB) in the Caribbean region of Colombia, showing exceptionally well-preserved planktonic foraminifera, calcareous nannofossils, and palynomorphs. We use these micropaleontological groups to perform integrated biostratigraphic analyzes and estimate the stratigraphic record's continuity and sedimentation rates for the early Neogene of the region. Two lithological intervals were defined, the first between 423.9 m and 345.8 m and the second between 345.8 m to the top of the core. Only palynomorphs were identified for the first interval of this section, assigned to the Cie ' naga de Oro Formation. We proposed an age no older than 19.49 Ma (Early Miocene, Burdigalian) based on the occurrence of Rugutricolpites intensus at 381.5 m. Although for the second interval, correlated with the Porquera Formation, we found three well-calibrated bioevents of calcareous microfossils, top of Sphenolithus belemnos at 213.2 m, base of Sphenolithus heteromorphus at 187.9 m, and top of Catapsydrax dis-similis at 141.9 m. In addition, we identified the top of uncalibrated planktonic foraminifera Trilobatus primordius, Globigerinoides altiaperturus, Paragloborotalia semivera, Paragloborotalia acrostoma, and Globoturborotalita pseudo-praebulloides. Our age model along the P-18 well indicates a time range from >= 19.01 Ma (Early Miocene, Bur-digalian) to-14.70 Ma (Middle Miocene, Langhian) equivalent to the calcareous nannofossils biozones NN3 to NN4, or, M3 to M5? Of planktonic foraminifera or palynological zones from T12 to T14? Even though we do not observe standard Middle Miocene bioevents with well-calibrated ages, the occurrence of nannofossils taxa Hel-icosphaera ampliaperta, and planktonic foraminifera Paragloborotalia semivera, Paragloborotalia acrostoma, and Globoturborotalita pseudopraebulloides show a distinctive biostratigraphic pattern, suggesting an age of-14.70 Ma to the top of the core section. Estimated sedimentation rates display high values (-120 m/Myr to-219 m/ Myr) during the Burdigallian (Early Miocene). They coincide with the regional subsidence increase during the Early Neogene in SSJB and Lower Magdalena Valley and the Early Miocene marine flooding event recorded in the Eastern Llanos Basin (ELB). From 17.60 Ma onwards, sedimentation rates decrease considerably, and a hiatus between 17.54 Ma and 16.96 Ma is interpreted as being tied to an abrupt change in sedimentology from calcareous mudrocks (marls) to very fine sandstones and sandy limestones. Finally, our data suggest that sedi-mentation rates in the basin were higher than marine sedimentation for ODP 999 during the same period.
- High-frequency glacial climate instability during the early pleistocene: insights from IODP site U1387 (Gulf of Cadiz)Publication . Trotta, Samanta; Duque Castaño, Monica Liliana; Rodrigues, Teresa; Voelker, Antje; Maiorano, Patrizia; Balestra, Barbara; Flores, José-Abel; Siniscalchi, Agata; Addante, Marina; Marino, MariaWe provide new high-resolution data on alkenone-derived sea surface temperature (SST) and calcareous plankton key taxa in temporally well constrained, high resolution benthic and planktonic oxygen isotope records at Integrated Ocean Drilling Program site U1387 in the Gulf of Cadiz. The investigated time interval encompasses the Early Pleistocene marine isotope stages (MIS) 48 to MIS 43. The aim is to evidence millennial climate variability during glacial phases of the “41 kyr world” and understand the impact of North Atlantic climate dynamics on the southern Portuguese margin. Neogloboquadrina pachyderma and Coccolithus pelagicus ssp. pelagicus record prominent, short-term abundance peaks concurrent with short-term SST minima and heavier values of ™18O in late MIS 48 and in the middle of MIS 46 and MIS 44. Superimposed on the obliquity and precession forcing, the wavelet analysis carried out on selected proxies (planktonic ™18O, N. pachyderma, C. pelagicus ssp. pelagicus, alkenone derived sea surface temperature) highlighted the occurrence of a higher frequency climate variability.
- Tropical ecosystem shifts at the Eocene–Oligocene transition in the southwestern Caribbean regionPublication . Trejos-Tamayo, Raúl; Garzón, Darwin; Ochoa, Diana; Plata-Torres, Angelo; Frontalini, Fabrizio; Vallejo-Hincapié, Felipe; Abrantes, Fatima; Magalhães, Vitor; Arias-Villegas, Viviana; Jaramillo, Carlos; Escobar, Jaime; Curtis, Jason H.; Flores, José-Abel; Osorio-Tabares, Constanza; Duque Castaño, Monica Liliana; Bedoya, Erika; Pardo-Trujillo, AndrésThe Eocene-Oligocene transition (EOT; similar to 34 Ma) marks a pivotal climatic shift from a warm, ice-free world to a cooler, glaciated climate driven by a significant decline in atmospheric pCO2 levels. This global cooling event, characterized by the first major Antarctic glaciation and a similar to 50 m sea-level fall, triggered selective extinctions in marine ecosystems and restructured sedimentary processes, making it one of the most significant climatic events of the Cenozoic. While the global impacts of the EOT are well documented, its effects on the marine environment of NW South America remain poorly understood. This region's unique position as a connection between the Pacific and Atlantic oceans before the closure of the Central American Seaway provides a valuable window into tropical ecosystem responses during this period. This study integrates micropaleontological and geochemical data from the ANH-SJ-1 drill core in the Colombian Caribbean to evaluate the impacts of global climatic shifts on tropical marine ecosystems. Palynological indicators, including the terrestrial/marine (T/M) index, along with XRF-derived elemental ratios (Zr/Rb, Ti/Al, K/Al, and K/Rb), reflect enhanced continental input during the EOT. These patterns suggest intensified erosion and detrital transport to bathyal depths, likely driven by rapid sea-level fall and hypopycnal flows. Calcareous nannofossil trophic indices reveal elevated surface productivity, likely fueled by increased continental nutrient influx, supported by higher Ba/Ti ratios that indicate enhanced organic matter export to the seafloor. The resulting oxygen depletion favored infaunal over epifaunal benthic foraminifera, marking a shift in community structure. Improved carbonate preservation across the transition, evidenced by a shift from agglutinated to calcareous benthic foraminifera and higher Ca/Ti ratios, reflects a deepening of the carbonate compensation depth (CCD), likely due to enhanced alkalinity from continental weathering. A positive delta 13Corg excursion (similar to 0.84 parts per thousand) aligns with global records and supports contributions from organic carbon oxidation, volcanic inputs, and weathering. Although limited by the number of available samples and low fossil abundances in some intervals, our multiproxy approach enables a coherent reconstruction of environmental dynamics. The ANH-SJ-1 record highlights the sensitivity of tropical systems to global climatic shifts and reinforces the importance of tropical data for understanding Cenozoic climate evolution and anticipating future ecosystem responses.