La Formación Zamoranos es una unidad carbonatada del Retiense que se sitúan por encima de las rocas de facies Keuper del Triásico Sudibérico. Se extiende desde Málaga hasta Murcia y Albacete. Esta formación presenta una gran variedad de facies volcanogenéticas en su miembre medio. Los niveles volcánicos pueden ser desde pocos centímetros hasta de varios metros. Suelen ser de tipo piroclástico, pero también existen depósitos volcanosedimentarios e intrusiones subvolcánicas.
Las rocas magmáticas estudiadas en la Fm Zamoranos revelan tres episodios volcánicos con dos tipos de afinidad geoquímica: alcalina (Grupo 1) y subalcalina (Grupos 2 y 3). Las rocas subalcalinas se asemejan al magmatismo descrito para la Provincia Magmática del Atlántico Central (CAMP) a escala global. Se identifica, además, rocas alcalinas que preceden a la fase subalcalina principal de CAMP en unos 15 Ma que es la primera evidencia de precursores alcalinos anteriores al magmatismo CAMP. La evolución del magmatismo se explica dentro de un contexto de rifting desarrollado durante el Triásico Superior. Se interpreta una mayor extensión de la Provincia Magmática del Atlántico Central hacia oriente, llegando hasta el SE del macizo Ibérico.
Sedimentary Geology, 2012, 247-248, 39-57
doi:10.1016/j.sedgeo.2011.12.012
Record of epicontinental platform evolution and volcanic activity during a major rifting phase: The Late Triassic Zamoranos Formation (Betic Cordillera, S Spain)
A. Pérez-López, F. Pérez-Valera and A. E. Götz
ABSTRACT
The study of the Late Triassic Zamoranos Formation and the comparison to coeval carbonate units provides new insights into the evolution and palaeogeography of carbonate platforms during major rifting phases in the Earth's history. The platform carbonates of the Zamoranos Formation record the last major transgression during the Triassic, and document the initial phase of the CAMP volcanism in the external Zone of the Betic Cordillera. New palynological data from the lower part of the Zamoranos Formation indicate a Middle Norian age. The entire succession is built up by limestones, dolomites, and ferruginous red detrital deposits with volcaniclastic breccias. The carbonates are interpreted as tidal and shallow marine sediments, deposited under arid conditions. The red detrital deposits appear in coastal environments in relation to a volcanic event, which triggered hydrothermal processes in these deposits and started the massive magmatic event associated with the Central Atlantic Magmatic Province (CAMP). The Zamoranos Formation was also recognized in the SW part of the Valencia Triassic and is correlated to the Imón Formation (Iberian Ranges), to the Isábena Formation (Pyrenees) and to other carbonate units of the W Tethys realm (Aquitaine, Tunisian Atlas, West Carpathians). These units indicate that an extensive epicontinental platform developed during the Late Triassic.
___________________________________
Lithos, 2021. Vol. 396-397, 106230.
https://doi.org/10.1016/j.lithos.2021.106230
Rhaetian tectono-magmatic evolution of the Central Atlantic Magmatic Province volcanism in the Betic Cordillera, South Iberia
Alberto Pérez-López, Aitor Cambeses, Fernando Pérez-Valera, Annette E. Götz
ABSTRACT
Volcanic rocks of the Zamoranos Formation exposed in the Betic Cordillera of southern Spain reveal Late Triassic CAMP volcanism extending from southwest to southeast of the Iberian massif. Comparison with volcanic rocks from the Upper Triassic of the Algarve region in Portugal enables correlation between these different magmatic provinces based on the striking geochemical similarity. The studied mafic magmatic rocks in the Betic Cordillera reveal three volcanic episodes during the deposition of the Zamoranos Formationwith two types of geochemical affinity: alkaline (Group 1) and sub-alkaline (Group 2 and 3). The sub-alkaline rocks resemble the studied Triassic rocks of Portugal and the magmatism described as CAMP on a global scale. In the present study, the identification of alkaline rocks preceding the main CAMP sub-alkaline phase by ca. 15 Ma, is the first evidence of alkaline precursors prior to CAMP magmatism and indicates a change from a prior deeper enriched mantle source to a subsequent, shallower one. The temporal evolution of alkaline magmatism followed by a CAMP-type sub-alkaline magmatismis best explained in a context of initial rifting during Norian-Rhaetian times. It is inferred that rifting gradually developed from west to east in the southern area of Iberia.