Sedimentology and Stratigraphy of the Upper Miocene El Boleo Formation, Santa Rosalía, Baja California, Mexico

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Auteur principal: Lucas Ochoa Landín
Format: Artículo científico
Langue:en
Publié: Universidad Nacional Autónoma de México 2000
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author Lucas Ochoa Landín
author_facet Lucas Ochoa Landín
contents Sedimentology and Stratigraphy of the Upper Miocene El Boleo Formation, Santa Rosalía, Baja California, Mexico Lucas Ochoa Landín Joaquín Ruiz Thierry Calmus Efrén Pérez Segura Francisco Escandón Ciencias de la Tierra Mexico Stratigraphy Sedimentology Upper Miocene Santa Rosalía The transtensional Upper Miocene Santa Rosalía basin, located in the east-central part of the BajaCalifornia Peninsula, consists of almost 500 m of non-marine to marine sedimentary deposits, andinterbedded tuffaceous beds. The Santa Rosalía basin is a NW-SE elongated fault-bounded depocenter thatrecords the sedimentation from Upper Miocene to Pleistocene time. The sequence is divided in El Boleo, LaGloria, Infierno and Santa Rosalía Formations. The lower most stratigraphic unit is the El Boleo Formation,a 200 to 300 m thick section composed in its lower part by a 1 to 5 m thick basal limestone and gypsumbodies followed by 170 to 300 m of clastic coarsening upward fan-delta, marine and nonmarine deposits.The upper clastic part of the El Boleo Formation show intraformational unconformities, synsedimentaryfolds and faults, and unidirectional sedimentary structures. These occur in at least three well organizedupward coarsening cycles (90-100 m thick). Each cycle represents a prograding fan-delta deposit formedprobably as consequence of large and repeated vertical movements of the basin floor with respect to thesource areas. This activity is related to the early stage of the opening of the Gulf of California. Each cyclestarted with the deposition of a unit composed by laminar fine-grained sediments accumulated in anextensive area covered by shallow standing fresh water with periodic introduction of subaqueous debrisflows. Each fine unit hosts Cu-Co-Zn ore bodies in the Santa Rosalía mining district. Lateral and verticalfacies changes are present in each depositional cycle, involving proximal coarse sandstone andconglomerates through fine sandstone characterized by planar and low angle cross bedding, alternating withsiltstone and mudstone with ripple lamination. Early, during the formation of the Santa Rosalía basin, twoancient depocenters located north-northwest and south-southeast of the basin were developed. Thesedepocenters were filled by sediments during the first cycle, and were separated by a ridge formed by thevolcanic rocks of the Comondú Formation. 2000 artículo científico 1026-8774 https://www.redalyc.org/articulo.oa?id=57217201 en http://www.redalyc.org/revista.oa?id=572 Revista Mexicana de Ciencias Geológicas application/pdf Universidad Nacional Autónoma de México Revista Mexicana de Ciencias Geológicas (México) Num.2 Vol.17
format Artículo científico
id redalyc_57217201
institution Redalyc
language en
publishDate 2000
publisher Universidad Nacional Autónoma de México
spellingShingle Sedimentology and Stratigraphy of the Upper Miocene El Boleo Formation, Santa Rosalía, Baja California, Mexico
Lucas Ochoa Landín
Ciencias de la Tierra
Mexico
Stratigraphy
Sedimentology
Upper Miocene
Santa Rosalía
Sedimentology and Stratigraphy of the Upper Miocene El Boleo Formation, Santa Rosalía, Baja California, Mexico Lucas Ochoa Landín Joaquín Ruiz Thierry Calmus Efrén Pérez Segura Francisco Escandón Ciencias de la Tierra Mexico Stratigraphy Sedimentology Upper Miocene Santa Rosalía The transtensional Upper Miocene Santa Rosalía basin, located in the east-central part of the BajaCalifornia Peninsula, consists of almost 500 m of non-marine to marine sedimentary deposits, andinterbedded tuffaceous beds. The Santa Rosalía basin is a NW-SE elongated fault-bounded depocenter thatrecords the sedimentation from Upper Miocene to Pleistocene time. The sequence is divided in El Boleo, LaGloria, Infierno and Santa Rosalía Formations. The lower most stratigraphic unit is the El Boleo Formation,a 200 to 300 m thick section composed in its lower part by a 1 to 5 m thick basal limestone and gypsumbodies followed by 170 to 300 m of clastic coarsening upward fan-delta, marine and nonmarine deposits.The upper clastic part of the El Boleo Formation show intraformational unconformities, synsedimentaryfolds and faults, and unidirectional sedimentary structures. These occur in at least three well organizedupward coarsening cycles (90-100 m thick). Each cycle represents a prograding fan-delta deposit formedprobably as consequence of large and repeated vertical movements of the basin floor with respect to thesource areas. This activity is related to the early stage of the opening of the Gulf of California. Each cyclestarted with the deposition of a unit composed by laminar fine-grained sediments accumulated in anextensive area covered by shallow standing fresh water with periodic introduction of subaqueous debrisflows. Each fine unit hosts Cu-Co-Zn ore bodies in the Santa Rosalía mining district. Lateral and verticalfacies changes are present in each depositional cycle, involving proximal coarse sandstone andconglomerates through fine sandstone characterized by planar and low angle cross bedding, alternating withsiltstone and mudstone with ripple lamination. Early, during the formation of the Santa Rosalía basin, twoancient depocenters located north-northwest and south-southeast of the basin were developed. Thesedepocenters were filled by sediments during the first cycle, and were separated by a ridge formed by thevolcanic rocks of the Comondú Formation. 2000 artículo científico 1026-8774 https://www.redalyc.org/articulo.oa?id=57217201 en http://www.redalyc.org/revista.oa?id=572 Revista Mexicana de Ciencias Geológicas application/pdf Universidad Nacional Autónoma de México Revista Mexicana de Ciencias Geológicas (México) Num.2 Vol.17
title Sedimentology and Stratigraphy of the Upper Miocene El Boleo Formation, Santa Rosalía, Baja California, Mexico
topic Ciencias de la Tierra
Mexico
Stratigraphy
Sedimentology
Upper Miocene
Santa Rosalía
url https://www.redalyc.org/articulo.oa?id=57217201