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| Formato: | Artículo científico |
| Lenguaje: | en |
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Universidad Autónoma de Baja California
2004
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| Acceso en línea: | https://www.redalyc.org/articulo.oa?id=48030209 |
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| _version_ | 1866814288526573568 |
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| author | Jonathan L. Payne |
| author_facet | Jonathan L. Payne |
| contents | Lower Cretaceous Alisitos Formation at Punta San Isidro: Coastal sedimentation and volcanism Jonathan L. Payne Jorge Ledesma Vázquez Markes E. Johnson Ciencias de la Tierra arc volcanism Rocky shorelines rudist limestone Alisitos Formation The Lower Cretaceous (Aptian-Albian) Alisitos Formation is well exposed at Punta San Isidro and adjacent sea cliffs on thePacific shores of Baja California near Eréndira, Mexico. Continuous coastal outcrops define a local stratigraphic succession lessthan 100 m in total thickness, including repetitious tuff, sandstone and conglomerate units interbedded with discontinuouslimestone beds rarely more than 2.5 m thick. The limestone beds are biostromal units that include scattered oysters and/or corals,as well as units dominated by the rudistid bivalve, Caprinuloidea perfecta. Two distinctive conglomerate units are composed ofandesite cobbles colonized by encrusting oysters in a quasi rocky-shore setting. One sandstone unit includes abundant fossilwood with tree limbs up to 55 cm long and 5 cm in diameter. Proximal volcanic activity is indicated by a series of dikes that cutthrough pyroclastic beds and lead to a 10-m thick andesitic flow that caps the succession at Punta San Isidro. Compared withthicker intervals of the Alisitos Formation elsewhere in Baja California that are dominated by andesitic flows and offshorelimestone, the Punta San Isidro sequence offers a window on a back-reef environment adjacent to a paleoshore that receivedpyroclastic lahars from a terrestrial origin or mass flows from shallow submarine explosions. Recovery of marine life and therenewal of a carbonate substrate followed successive episodes of volcanism and massive erosion along an active coastline. Thisscenario is very different from depositional processes of the Upper Cretaceous (Campanian-Maastrichtian) Rosario Formationthat cannibalized and subsequently formed a regional unconformity against tilted Alisitos strata with substantial topographicrelief in the Eréndira region. 2004 artículo científico 0185-3880 https://www.redalyc.org/articulo.oa?id=48030209 en http://www.redalyc.org/revista.oa?id=480 Ciencias Marinas application/pdf Universidad Autónoma de Baja California Ciencias Marinas (México) Num.2 Vol.30 |
| format | Artículo científico |
| id | redalyc_48030209 |
| language | en |
| publishDate | 2004 |
| publisher | Universidad Autónoma de Baja California |
| spellingShingle | Lower Cretaceous Alisitos Formation at Punta San Isidro: Coastal sedimentation and volcanism Jonathan L. Payne Ciencias de la Tierra arc volcanism Rocky shorelines rudist limestone Alisitos Formation Lower Cretaceous Alisitos Formation at Punta San Isidro: Coastal sedimentation and volcanism Jonathan L. Payne Jorge Ledesma Vázquez Markes E. Johnson Ciencias de la Tierra arc volcanism Rocky shorelines rudist limestone Alisitos Formation The Lower Cretaceous (Aptian-Albian) Alisitos Formation is well exposed at Punta San Isidro and adjacent sea cliffs on thePacific shores of Baja California near Eréndira, Mexico. Continuous coastal outcrops define a local stratigraphic succession lessthan 100 m in total thickness, including repetitious tuff, sandstone and conglomerate units interbedded with discontinuouslimestone beds rarely more than 2.5 m thick. The limestone beds are biostromal units that include scattered oysters and/or corals,as well as units dominated by the rudistid bivalve, Caprinuloidea perfecta. Two distinctive conglomerate units are composed ofandesite cobbles colonized by encrusting oysters in a quasi rocky-shore setting. One sandstone unit includes abundant fossilwood with tree limbs up to 55 cm long and 5 cm in diameter. Proximal volcanic activity is indicated by a series of dikes that cutthrough pyroclastic beds and lead to a 10-m thick andesitic flow that caps the succession at Punta San Isidro. Compared withthicker intervals of the Alisitos Formation elsewhere in Baja California that are dominated by andesitic flows and offshorelimestone, the Punta San Isidro sequence offers a window on a back-reef environment adjacent to a paleoshore that receivedpyroclastic lahars from a terrestrial origin or mass flows from shallow submarine explosions. Recovery of marine life and therenewal of a carbonate substrate followed successive episodes of volcanism and massive erosion along an active coastline. Thisscenario is very different from depositional processes of the Upper Cretaceous (Campanian-Maastrichtian) Rosario Formationthat cannibalized and subsequently formed a regional unconformity against tilted Alisitos strata with substantial topographicrelief in the Eréndira region. 2004 artículo científico 0185-3880 https://www.redalyc.org/articulo.oa?id=48030209 en http://www.redalyc.org/revista.oa?id=480 Ciencias Marinas application/pdf Universidad Autónoma de Baja California Ciencias Marinas (México) Num.2 Vol.30 |
| title | Lower Cretaceous Alisitos Formation at Punta San Isidro: Coastal sedimentation and volcanism |
| topic | Ciencias de la Tierra arc volcanism Rocky shorelines rudist limestone Alisitos Formation |
| url | https://www.redalyc.org/articulo.oa?id=48030209 |