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Alberto Carlos Riccardi

Bio: Alberto Carlos Riccardi is an academic researcher from National University of La Plata. The author has contributed to research in topics: Ammonite & Biostratigraphy. The author has an hindex of 21, co-authored 80 publications receiving 1480 citations. Previous affiliations of Alberto Carlos Riccardi include National Scientific and Technical Research Council.
Topics: Ammonite, Biostratigraphy, Aptian, Cretaceous, Genus


Papers
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Journal ArticleDOI
TL;DR: The first record of the Early Toarcian Oceanic Anoxic Event ( c. 183 Ma) from the Southern Hemisphere is described from the Neuquen Basin, Argentina, identified chemostratigraphically on the basis of a relative increase in marine organic carbon and a characteristic negative carbon-isotope excursion (δ 13 C org ) in bulk rock and fossil wood.
Abstract: The first record of the Early Toarcian Oceanic Anoxic Event ( c . 183 Ma) from the Southern Hemisphere is described from the Neuquen Basin, Argentina, identified chemostratigraphically on the basis of a relative increase in marine organic carbon and a characteristic negative carbon-isotope excursion (δ 13 C org ) in bulk rock and fossil wood. The negative excursion of −6‰ in bulk organic carbon (falling to −31.3‰) crosses the boundary of the tenuicostatum – hoelderi Andean ammonite Zones, equivalent to the tenuicostatum – falciferum / serpentinum zones of Europe. These data indicate that the Early Toarcian Oceanic Anoxic Event was a global phenomenon. Supplementary material: A detailed stratigraphic log, chemostratigraphic data and nannofossil data are available at http://www.geolsoc.org.uk/SUP18411.

138 citations

Journal ArticleDOI
TL;DR: In this paper, the affinities of the ammonoid faunas from central-west and southern South America are used to analyze the evolution of seaways and oceanic connections with Tethys during the Jurassic and Cretaceous.

134 citations

Journal ArticleDOI
TL;DR: Kietzmann et al. as discussed by the authors presented a study of the relationship between the Nacional de Investigaciones Cientificas y Tecnicas and the Instituto de Estudios Andinos "Don Pablo Groeber".

104 citations


Cited by
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Journal ArticleDOI
TL;DR: In the case of the Cenomanian-Turonian and early Aptian OAEs, a longer-term trend to less radiogenic values was observed as discussed by the authors.
Abstract: [1] Oceanic anoxic events (OAEs) record profound changes in the climatic and paleoceanographic state of the planet and represent major disturbances in the global carbon cycle. OAEs that manifestly caused major chemical change in the Mesozoic Ocean include those of the early Toarcian (Posidonienschiefer event, T-OAE, ∼183 Ma), early Aptian (Selli event, OAE 1a, ∼120 Ma), early Albian (Paquier event, OAE 1b, ∼111 Ma), and Cenomanian–Turonian (Bonarelli event, C/T OAE, OAE 2, ∼93 Ma). Currently available data suggest that the major forcing function behind OAEs was an abrupt rise in temperature, induced by rapid influx of CO2 into the atmosphere from volcanogenic and/or methanogenic sources. Global warming was accompanied by an accelerated hydrological cycle, increased continental weathering, enhanced nutrient discharge to oceans and lakes, intensified upwelling, and an increase in organic productivity. An increase in continental weathering is typically recorded by transient increases in the seawater values of 87Sr/86Sr and 187Os/188Os ratios acting against, in the case of the Cenomanian-Turonian and early Aptian OAEs, a longer-term trend to less radiogenic values. This latter trend indicates that hydrothermally and volcanically sourced nutrients may also have stimulated local increases in organic productivity. Increased flux of organic matter favored intense oxygen demand in the water column, as well as increased rates of marine and lacustrine carbon burial. Particularly in those restricted oceans and seaways where density stratification was favored by paleogeography and significant fluvial input, conditions could readily evolve from poorly oxygenated to anoxic and ultimately euxinic (i.e., sulfidic), this latter state being geochemically the most significant. The progressive evolution in redox conditions through phases of denitrification/anammox, through to sulfate reduction accompanied by water column precipitation of pyrite framboids, resulted in fractionation of many isotope systems (e.g., N, S, Fe, Mo, and U) and mobilization and incorporation of certain trace elements into carbonates (Mn), sulfides, and organic matter. Sequestration of CO2 in organic-rich black shales and by reaction with silicate rocks exposed on continents would ultimately restore climatic equilibrium but at the expense of massive chemical change in the oceans and over time scales of tens to hundreds of thousands of years.

1,144 citations

Journal ArticleDOI
TL;DR: A significant number of new palaeomagnetic poles have become available since the last time a compilation was made (assembled in 2005, published in 2008) to indicate to us that a new and significantly expanded set of tables with palaeOMagnetic results would be valuable, with results coming from the Gondwana cratonic elements, Laurentia, Baltica/Europe, and Siberia as mentioned in this paper.

1,094 citations

Journal ArticleDOI
TL;DR: A review of sea-level changes during the big five mass extinctions and several lesser extinction events reveals that the majority coincide with large eustatic inflexions as discussed by the authors, with the most frequent extinctions occurring during the transgressive pulse when anoxic bottom waters often became extensive.

595 citations

01 May 2001
TL;DR: A review of sea-level changes during the big five mass extinctions and several lesser extinction events reveals that the majority coincide with large eustatic inflexions as mentioned in this paper, with the most frequent extinctions occurring during the transgressive pulse when anoxic bottom waters often became extensive.
Abstract: Review of sea-level changes during the big five mass extinctions and several lesser extinction events reveals that the majority coincide with large eustatic inflexions. The degree of certainty with which these eustatic oscillations are known varies considerably. Thus, the late Ordovician and end Cretaceous extinctions are associated with unequivocal, major regressions demonstrated from numerous, widespread regions. In contrast, the multiple, high frequency sea-level changes reported for the Frasnian–Famennian crisis (based on the supposed depth-preferences of conodont taxa) have little support from sequence stratigraphic analyses, which reveals the interval to be one of highstand. The end Permian mass extinction has long been related to a severe, first order lowstand of sea level [Newell, N.D., 1967. Revolutions in the history of life. Geol. Soc. Am. Spec. Pap. 89, 63–91.] based primarily on the widespread absence of latest Permian ammonoid markers, but field evidence reveals that the interval coincides with a major transgression. Newell's hypothesis that marine extinctions are related to shelf habitat loss during severe regression remains tenable for the end Guadalupian and end Triassic extinction events but not for other crises. Rapid high amplitude regressive–transgressive couplets are the most frequently observed eustatic changes at times of mass extinction, with the majority of extinctions occurring during the transgressive pulse when anoxic bottom waters often became extensive. The ultimate cause of the sea-level changes is generally unclear. A glacioeustatic driving mechanism can only be convincingly demonstrated for the end Ordovician and end Devonian events. At other times, it is speculated that they may relate to the widespread regional doming (and subsequent collapse) caused by the impingement of superplumes (and ultimate eruption) on the base of the lithosphere.

569 citations

Book ChapterDOI
01 Jan 2012
TL;DR: The geomagnetic polarity time scale for the past 160 myr is constructed by fitting spreading-rate models to these constraints as discussed by the authors, which is summarized in the appropriate period chapters.
Abstract: The patterns of marine magnetic anomalies for the Late Cretaceous through Neogene (C-sequence) and Middle Jurassic through Early Cretaceous (M-sequence with deep-tow extension) have been calibrated through magnetostratigraphic studies to biostratigraphy, cyclostratigraphy and selected radio-isotope-dated levels. The majority of the geomagnetic polarity time scale for the past 160 myr is constructed by fitting spreading-rate models to these constraints. The status of the geomagnetic polarity time scale for each geological period is summarized in the appropriate period chapters.

560 citations