Person: Pérez Garrido, Carlos
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First Name
Carlos
Last Name
Pérez Garrido
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Ciencias Geológicas
Department
Mineralogía y Petrología
Area
Cristalografía y Mineralogía
Identifiers
4 results
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Item Coastal wetlands as markers of transgression in proximal extensional systems (Berriasian, W Cameros Basin, Spain)(Journal of Iberian Geology, 2019) Mas Mayoral, José Ramón; Arribas Mocoroa, María Eugenia; González Acebrón, Laura; Quijada, Isabel Emma; Campos-Soto, S.; Suárez González, Pablo; Sacristán Horcajada, Sara; Arribas Mocoroa, José; Benito Moreno, María Isabel; Pérez Garrido, Carlos; Alonso Millán, ÁngelaThe early stages of intraplate extensional systems commonly are recorded by deposition of continental sediments. In this context, given appropriate tectonics and eustasy, transgressions can be well recorded in the areas of the basins located close to the sea, but they may be difficult to recognize in the innermost landwards areas of the system. This situation occurs in the innermost Upper Jurassic-Early Cretaceous Cameros Basin, part of the Iberian Extensional System (N. Spain), where a Berriasian transgression is recorded. The Berriasian succession in this area consists of siliciclastic deposits (sandstone and mudstone) of the Salcedal Formation and of carbonate and mixed carbonate-fine siliciclastic deposits (limestone and marl) of the San Marcos Formation. The sedimentological analysis of this depositional succession indicates that a Berriasian carbonate coastal wetland system occupied that sector of the Cameros Basin during deposition of the San Marcos Formation. This carbonate coastal wetland system consisted of shallow and quiet water bodies including some with marine influence others with no to very little marine influence, and palustrine areas. A semiarid climate characterized by the seasonal alternation of short wet and long dry periods caused water bodies of the system to undergo episodic desiccation and subaerial exposure. Moreover, this complex mosaic of sub-environments was connected laterally with a distal zone of a distributive fluvial system that was rimmed by siliciclastic tidal flats during phases of greater marine influence. The paleogeographic arrangement of this coastal wetland depositional system indicates that the marine influence came from the Basque-Cantabrian Basin to the north. During the period of Berriasian maximum marine influence, accommodation linked to the eustatic rise added to accommodation generated by tectonic subsidence from the extensional reactivation of late Variscan strike-slip faults. All these factors favored marine incursion into the west Cameros Basin from the Basque-Cantabrian Basin to the north. The example of the Berriasian transgression recorded in the W Cameros Basin by establishment of coastal wetland systems matches the interpretations of previous studies in neighboring areas. In those areas, complex coastal systems record transgressions in the innermost parts of the intraplate extensional basins of the Iberian Plate. This observation suggests that this paleogeographic and sedimentological arrangement may be common in the innermost parts of intraplate extensional basins during transgressive episodes throughout the geological record.Item Diagenetic albitization in the Tera Group, Cameros Basin (NE Spain) recorded by trace elements and spectral cathodoluminescence(Chemical geology, 2012) González Acebrón, Laura; Götze, Jens; Barca, Donatella; Arribas Mocoroa, José; Mas Mayoral, José Ramón; Pérez Garrido, CarlosThis paper deals with the diagenetic albitization of both plagioclases and K-feldspars in the Tithonian fluvial sandstones of a rift basin (Cameros Basin). The sandstones in the lower part of the rift record have not suffered this albitization process. A clear relationship is observed between sodium contents, as the main element of some feldspars and their cathodoluminescence (CL) color (the higher the sodium content, the lower is their CL intensity). In conclusion, albitization processes are detectable by decreased CL intensities and changes in the CL spectra. In addition, very different trace element compositions are obtained by laser ablation when comparing trace elements of non-albitized feldspars in sandstones of the lower part of the rift record with those of albitized feldspars in sandstones of the infill top. Non-albitized K-feldspars show Rb, Sr, Ba and Pb contents of up to 1000 ppm. In contrast, very flat profiles of trace element contents (< 250 ppm) are recorded in albitized feldspars (both K-feldspars and plagioclases). Thus, albitization implies feldspars impoverished in trace elements, including REE, which suggests that albitization is a dissolution and reprecipitation process. Further, albitized plagioclases show higher REE contents than albitized K-feldspars. We report here that REE patterns partly depend on the initial composition of the feldspar (K-feldspar or plagioclase) as a useful geochemical criterion for distinguishing albitized detrital plagioclases from albitized detrital K-feldspars. CL spectra from non-albitized and albitized K-feldspars and plagioclases revealed marked differences. Non-albitized K-feldspars present blue (main emission band at 460 nm) and brownish CL colors (590 nm), sometimes in the same grain. Brownish colors are related to weathering processes. The primary blue emission is related to Al–O−–Al centers, enhanced probably by Al incorporation due to the coupled substitution of Ba2+ + Al3+ ↔ M+ + Si4+. Weathered K-feldspars present 4.8 times lower Ba content than fresh blue luminescent ones. The brownish colors are related to the external border or fractured grain zones, altered by weathering processes. Therefore, the observed 590 nm emission is assumed to be caused by structural defects resulting from weathering and alteration. Albitized K-feldspars are usually weak luminescent with a typical CL emission band at 620 nm. Sometimes, relicts of the original blue luminescence (460 nm band) are still present. The leaching of probably both Al and Ba can be responsible for the decrease in the blue band. The characteristic 620 nm band is also dominant in albitized weak luminescent plagioclases. Two additional emission bands at 440 nm (Al–O−–Al center) and 565 nm (Mn2+) occur, when albitized plagioclases preserved their original CL characteristics (green CL color). Another spectral peak at ca. 720 nm can be explained by Fe3+ activation due to Fe3+–Al3+ substitution. The spectral CL measurements indicate that changes in luminescence due to albitization (620 nm emission) seem to be more related to structural defects than to trace element activation or quenching.Item Very coarse-grained beaches as a response to generalized sea level drops in a complex active tectonic setting: Pleistocene marine terraces at the Cadiz coast, SW Spain(Marine Geology, 2016) González Acebrón, Laura; Mas Mayoral, José Ramón; Arribas Mocoroa, José; Gutiérrez Mas, José Manuel; Pérez Garrido, CarlosThe studied Pleistocene deposits at the Cadiz coast are located on the current intertidal zone or at cliffs parallel to the actual coast (6.50 m a.s.l.) from the localities of El Puerto de Santa María to Chiclana. Five sequences of very coarse-grained beaches have been recognized and dated. They unconformably overlie Pliocene units and are formed by clast-supported conglomerate and coarse-grained sandstone. Chronological ages (⁸⁷Sr/⁸⁶Sr and AMS ¹⁴C analysis) and stratigraphic correlation stand that the oldest marine terrace is the one placed topographically higher and towards the SE of Cadiz city, dated as Early Pleistocene (1.3 Ma). After it, the sea retreatment produces subaerial exposure of Sequence 1 and the development of several calcrete profiles and a paleokarst. Subsequent sea-level rises allow the sedimentation of Sequences 2, 3 and 4 during Early-Middle Pleistocene (1 to 0.8 Ma) in areas close to Cadiz city, with subaerial exposure recorded at the top of Sequences 3 and 4. During the very Upper Pleistocene, sedimentation of Sequence 5 occurs towards the SE of Cadiz city. Based on the spatial position of Sequence 5 we can conclude that this area constituted a downthrown block during the Latest Pleistocene, in relation to neotectonic processes and diapirismItem Reply to comment on González-Acebrón, L., Mas, R., Arribas, J., Gutiérrez-Mas, J.M., Pérez-Garrido, C. “Very coarse-grained beaches as a response to generalized sea level drops in a complex active tectonic setting: Pleistocene marine terraces at the Cadiz coast, SW Spain”(Marine Geology, 2019) González Acebrón, Laura; Mas Mayoral, José Ramón; Arribas Mocoroa, José; Gutiérrez-Mas, José Manuel; Pérez Garrido, CarlosA series of Pleistocene marine terraces comprised of conglomerate and coarse-grained sandstone aligned NNW-SSE along the Cadiz coast have been recognized and interpreted as formed in very coarse-grained beaches in our work (González-Acebrón et al., 2016). They unconformable overlie either Pliocene units or older Pleistocene deposits. In these terraces, five sedimentary sequences were described and dated by Sr isotopic analysis of well-preserved oysters. This dating provided an Early Pleistocene age (1.3 Ma) for the oldest marine terrace, which corresponds to Sequence 1. Aguirre (2018) does not agree with the dating of the first sequence. Instead, in Aguirre (1995) and Aguirre et al. (1995) these deposits are considered as laterally equivalent to lacustrine deposits located more than 50 km far away (Mesas de Asta, Jerez Basin), and their age (Late Pliocene-lowermost Early Pleistocene) extrapolated to Sequence 1. This is an impossible correlation given the fact that the studied deposits (Sequences 1 to 5) are marine terraces without lateral continuity inland. Finally, Aguirre's (2018) sedimentological interpretation of the deposits of Sequence 1 as part of a “wave- and tide-dominated delta” breaks down when one considers that this delta would be a mixture of non-coeval deposits (the continental deposits of Mesas de Asta together with Sequence 1 deposits).