Cenozoic phosphatic deposits in North Patagonia, Argentina: Phosphogenesis, sequence-stratigraphy and paleoceanography

Scasso, Roberto A.; Castro, Liliana Norma

doi:10.1016/s0895-9811(99)00035-8

Cited by 47 publications

(69 citation statements)

References 23 publications

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“…). The Gaiman Formation was deposited in a shallow‐marine environment (Scasso et al ., ; Scasso & Castro, ) and consists of a coarsening‐upward succession of poorly consolidated mudstones, tuffs, sandstones and coquinas (Fig. ).…”

Section: Geology Of the Study Areamentioning

confidence: 99%

“…The presence of abundant fresh and slightly reworked volcanic glass (Mendía & Bayarsky, ) indicates a dominant provenance from contemporaneous volcanic products for the clastic sediments. Subordinate sources were the tuff deposits of the underlying Sarmiento Formation, the Upper Jurassic volcanic succession and crystalline basement that crop out in the area (Scasso & Castro, ).…”

Section: Geology Of the Study Areamentioning

confidence: 99%

“…Two types of phosphatic horizons are recognized (Scasso & Castro, ): ‘Type 1’ consists of in situ concretions about 10 cm in diameter, dispersed in the host sediments, usually tuffaceous sandy mudstones, wackes or tuffs. These deposits were interpreted by Scasso & Castro () as condensed beds associated with long periods of slow sedimentation, part of transgressive to early highstand system tracts. ‘Type 2’ phosphates are related to autochthonous reworking, winnowing and mechanical concentration of resistant particles.…”

Section: Phosphatic Horizons and Phosphogenesismentioning

confidence: 99%

“…Case examples of phosphate precipitation associated with other types of substrates are uncommon. The present study took advantage of a rare type of phosphate concretion developed on vitric, non‐welded tuffs interbedded in the shallow marine Neogene sequence of the Gaiman Formation (Leanza et al ., ; Scasso & Castro, ), in order to investigate the processes of concentration and precipitation/replacement of phosphate. Textural changes, together with the novel use of isocon diagrams, allowed an assessment of subtle trace element changes in glass particles prior to and during phosphate precipitation.…”

Section: Introductionmentioning

confidence: 99%

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Association of phosphate with rhyolite glass in marine Neogene tuffs from Patagonia, Argentina

et al. 2013

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The precipitation/replacement of Ca-phosphate is a complex process that commonly takes place during the early diagenesis in marine sediments. The unusual occurrence of shallow marine, early diagenetic phosphatic deposits associated with glassy tuffs in the Neogene Gaiman Formation, in the Chubut Province, Patagonia, Argentina, constitutes a good case example for the study of replacement and precipitation of Ca-phosphate on an unstable substrate. Isocon diagrams illustrate that chemical changes during glass diagenesis include gains in loss on ignition and Ca, and losses of K. These changes are the result of glass hydration during sea water-glass interaction, together with adsorption and diffusion of ions into the bulk shard; combined, these represent an incipient process of volcanic glass replacement by Caphosphate. Subsequent early diagenetic P enrichment in the pore solutions led to phosphate precipitation, associated with pitting on the glass shards and pumice. The associated development of a reactive surface promoted the incorporation of P and Ca into their margins. Lastly, precipitation of calcium phosphate filled the vesicles and other open cavities, inhibiting further glass dissolution. The high porosity and reactivity of the volcanic glass provided an appropriate substrate for phosphate precipitation, leading to the development of authigenic apatite concretions in the volcanic-glass bearing strata of the Gaiman Formation. This research is of significance for those concerned with marine phosphatic deposits and sheds light on the processes of early diagenetic phosphate precipitation by replacement of an atypical, unstable substrate like hydrated volcanic glass.

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Section: Geology Of the Study Areamentioning

confidence: 99%

Section: Geology Of the Study Areamentioning

confidence: 99%

Section: Phosphatic Horizons and Phosphogenesismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Association of phosphate with rhyolite glass in marine Neogene tuffs from Patagonia, Argentina

et al. 2013

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“…This formation was deposited during the 'Patagoniense' and most of the early Miocene marine vertebrates known for northern Patagonia were obtained there. Vertebrate remains were found in two reworked and winnowed lags associated with transgressive surfaces, which display a concentration of phosphatic concretions, ooids, bones and teeth, decapod remains, and some large shells, collectively constituting condensed deposits (lower and upper T2 levels of Scasso & Castro, 1999). The beds of the 'Entrerriense' overlying the Gaiman Formation in the Península Valdés area were included in the Puerto Madryn Formation (Haller, 1979).…”

Section: Geological Contextmentioning

confidence: 99%

Marine vertebrate assemblages in the southwest Atlantic during the Miocene

Cione

Cozzuol

Dozo

et al. 2011

Biological Journal of the Linnean Society

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Two biogeographical units are generally recognized in the present shelf area of Argentina: the Magellanian and Argentinian Provinces. The two provinces differ in their fossil record. The evolution of these provinces has been characterized by migrations, extinctions, pseudoextinctions and, perhaps, even speciation events. Marine vertebrate assemblages with some similarities to the Argentinian fauna were already present in the Miocene, whereas no associations similar to those of the Magellanian fauna have been found in South America before the Pleistocene. Two successive major marine transgressions flooded northern Patagonia during the Miocene: the ‘Patagoniense’ (Early Miocene) and the ‘Entrerriense’ (Middle to Late Miocene). We analyse three rich fossil assemblages that were formed during these transgressions. The absence of Magellanian Miocene vertebrate assemblages is consistent with the hypothesis of a more southern distribution of the cold‐temperate fauna at that time. In Patagonia, as in other regions, an increased number of living groups appeared from the Lower to Upper Miocene. The Late Miocene aquatic mammals had a modern aspect, and some of the fish species are still living in the South Atlantic Ocean. In this contribution, we stress that warm‐temperate fishes and a high diversity of penguins are found together at the base of the Gaiman Formation. We hypothesize that penguins were adapted to live in warmer waters than those of the latest Cenozoic and the Recent. Finally, we recall that many taxa became extirpated because of the global temperature drops of the late Cenozoic. However, some fishes and pinnipeds which were extirpated only in the Atlantic Ocean are discussed here. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 103, 423–440. Actualmente se reconocen dos provincias biogeográficas en la plataforma marina argentina actual: la Magallánica y la Argentina. Las dos unidades difieren en su registro fósil. Se sugiere aquí que la evolución de las provincias fue compleja y caracterizada por migraciones, eventos de especiación, extinciones, pseudoextinciones. Durante el Mioceno ya había asociaciones de vertebrados marinos con similitudes taxonómicas con los de la Provincia Argentina pero no se detectaron hasta ahora asociaciones fósiles similares a las de la Magallánica hasta el Pleistoceno. Aquí describimos tres ricas asociaciones faunísticas marinas del Mioceno que se depositaron durante dos grandes transgresiones atlánticas: el ‘Patagoniense’ (Mioceno Temprano) y el ‘Entrerriense’ (Mioceno Medio a Tardío). La ausencia de asociaciones de tipo magallánicas en el Mioceno confirma la hipótesis de que la fauna templado‐fría se distribuía más al sur en ese tiempo. En Patagonia, tal como en otras áreas, se registra un número mayor de formas actuales desde el Mioceno Temprano al Tardío. Los mamíferos acuáticos del Mioceno Tardío tenían un aspecto moderno; incluso alguna de las especies de peces perdura en la actualidad. Asimismo, en este trabajo llamamos la atención sobr...

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Geology of Península Valdés

Haller

2017

Late Cenozoic of Península Valdés, Patagonia, Argentina

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Cenozoic phosphatic deposits in North Patagonia, Argentina: Phosphogenesis, sequence-stratigraphy and paleoceanography

Cited by 47 publications

References 23 publications

Association of phosphate with rhyolite glass in marine Neogene tuffs from Patagonia, Argentina

Association of phosphate with rhyolite glass in marine Neogene tuffs from Patagonia, Argentina

Marine vertebrate assemblages in the southwest Atlantic during the Miocene

Geology of Península Valdés

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