Late Cretaceous radiolarian biochronology of the Pedro Brand section, Tireo Group, eastern Central Cordillera, Dominican Republic: A contribution to the stratigraphy of the Caribbean Large Igneous Province

• Published in: Revue de Micropaléontologie
• Main Authors: Sandoval, M. Isabel, Baumgartner, Peter O., Escuder-Viruete, J., Gabites, J., Mercier de Lépinay, Bernard
• Other Authors: Institut des Sciences de la Terre, Université de Lausanne = University of Lausanne (UNIL), Instituto Geológico y Minero de España (IGME), Pacific Center for Isotopic and Geochemical Research, Géoazur (GEOAZUR 7329), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD France-Sud )
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2015
• Subjects: [SDU.STU]Sciences of the Universe [physics]/Earth Sciences; Pacific; Duarte; Loma; Planktonic foraminifera
• Online Access: https://hal.science/hal-01380981; https://doi.org/10.1016/j.revmic.2015.02.002

International audience The Tireo Group in the eastern Central Cordillera (Dominican Republic) is part of the Jarabacoa Block, composed of a Pacific-type Jurassic ocean floor (Loma La Monja, overlain by the El Aguacate ribbon Chert), intruded and overlain by an early CLIP (Carribean Large Igneous Province)-type plateau, the Duarte Complex, which is in turn unconformably overlain by arc-type rocks of the Tireo Group. This group exhibits a 3-km thick sequence of arc-related volcanic and volcano-sedimentary rocks, including tuffaceous chert and mudstone studied for radiolarians in this paper. The Siete Cabezas Formation, considered to be the last Campanian–Maastrichtian CLIP-type volcano-sedimentary sequence, overlies the Tireo Group. A controversy about earlier radiolarian dating of the Tireo Group, considered until now as part of the Siete Cabezas Formation, encouraged us to study a well-exposed section located 3 km NE of Pedro Brand village. Seven samples of laminated siliceous mudstones and cherts yielded around 40 common and well-preserved radiolarian taxa. Based on maximum ranges of taxa published in several regional zonations and on a comparison with a Turonian–Coniacian sample calibrated by planktonic foraminifera (the Deva Beds from Romania), we determine a Turonian–Coniacian age for the Pedro Brand section. A 40Ar–39Ar whole rock age of 75.1 ± 1.1 Ma, obtained in a basalt dyke crosscutting the radiolarian bearing rocks, provides a Late Campanian consistent minimum age for the pelagic–hemipelagic Pedro Brand section. Including the re-interpretation of earlier radiolarian work, we conclude that the studied rocks of the Tireo Group are older than the Maastrichtian 40Ar–39Ar ages on plagioclase of the Siete Cabezas Formation. The studied dyke in the Pedro Brand section geochemically resembles the overlying Siete Cabezas and Pico Duarte basalts and could be a feeder dyke of those. However, a tectonic superposition of the Siete Cabezas cannot be excluded, since earlier 40K–40Ar basalt ages of this unit are ...