Unsteady and spatially variable evolution of the Neogene Andean Bermejo foreland basin, Argentina

Jordan, Teresa E.; Schlunegger, Fritz; Cardozo, Néstor

doi:10.1016/s0895-9811(01)00072-4

Cited by 116 publications

(186 citation statements)

References 41 publications

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“…The presence of cross-stratified beds with a flat base indicates occasional transport of sand grains as bedload by unconfined subcritical flows (Southhard 1991). The combination of these sedimentological features indicates deposition on a gently dipping terrestrial plain presumably under arid climatic conditions (e.g., Jordan et al 2001).…”

Section: Sandstone Unitmentioning

confidence: 99%

Sedimentological and palynological constraints on the basal Triassic sequence in Central Switzerland

et al. 2007

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In Central Switzerland, Mesozoic sedimentation began after erosion and peneplainisation of the Hercynian relief and late Paleozoic continental deposition in SW-NE striking pull-apart basins. The first Triassic sedimentary sequence overlaying a weathered crystalline basement consists of a relatively thin (<10 m), lithologically highly variable unit with coarse-grained siliciclastic deposits at the base, grading into a mixed sandstone/shale-dolomite sequence followed by well-bedded dolomites with chert nodules.Sedimentary texture analyses and petrological investigations revealed four different sedimentary units starting at the base with a regolith unit that represents the weathered crystalline basement. It is overlain by terrestrial plain deposits, followed by mixed siliciclastic-carbonaceous sediments and a sequence of dolomites, deposited between the supralittoral and eulittoral zones of a tidal flat (Mels-Formation), and the eulittoral to sublittoral zones of a carbonate tidal flat environment (Röti-Dolomit), respectively.Palynological data from four localities in Central Switzerland indicate a heterochronous early Anisian age (Aegean -Bithynian/Pelsonian) for the supra-to eulittoral mixed siliciclastic-carbonaceous sediments. These new biostratigraphic ages suggest that the first Triassic marine transgression in Central Switzerland is time equivalent with those of the basal Wellendolomit in Northern Switzerland but slightly older than in the Germanic Basin. Consequently, Central Switzerland was located at this time at the northern shoreline of the Tethys and not on the southern limit of the Germanic Basin. ZUSAMMENFASSUNGDie mesozoische Sedimentation begann in der Zentralschweiz nach einer erosiven Phase des herzynischen Gebirges und der Ablagerung spätpaläozoischer klastisch-kontinentaler Sedimente in SW-NE gerichteten transpressiven Grä-ben. Die frühesten triadischen Ablagerungen, die den verwitterten kristallinen Untergrund überdecken, sind eine meist geringmächtige (< 10 m) Sequenz von grobkörnigen Siliziklastika, gefolgt von einer Wechsellagerung von Sandsteinen, Tonsteinen und Dolomit, die durch gut gebankte Dolomite mit Hornstein-Konkretionen überlagert werden.Detaillierte sedimentologische und petrographische Analysen führten zur Unterteilung der Sequenz in 4 Einheiten, beginnend mit einem basalen Regolith, dem Verwitterungsgrus des kristallinen Untergrundes. Im Hangenden folgt als erstes eine terrestrische, siliziklastische Einheit, die von einer suprabis eulitoralen siliziklastisch-karbonatischen Wechselfolge einer Wattenfläche (Mels-Formation) überlagert wird. Im Hangenden treten gut geschichtete Dolomite des eu-bis sublitoralen Bereichs eines Karbonatwatts (Röti-Dolomit) auf.Palynologische Daten von vier Lokalitäten in der Zentralschweiz deuten auf eine heterochrone marine Transgression (Aegean bis Bithynian/Pelsonian) der supra-bis eulitoralen, siliziklastisch-karbonatischen basalen Triassedimente hin. Diese neuen biostratigraphischen Daten zeigen, dass die erste marine Transgression in de...

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Section: Sandstone Unitmentioning

confidence: 99%

Sedimentological and palynological constraints on the basal Triassic sequence in Central Switzerland

et al. 2007

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“…The southern segment of the Central Andes is characterized by a complex volcanic and tecto-sedimentary evolution, both in time and space (e.g., Jordan et al 1983Jordan et al , 1993Jordan et al , 2001Marrett and Strecker 2000;Kay and Mpodozis 2002;Dávila and Astini 2007). This evolution has been recorded in numerous retroarc foreland basins and subbasins, which contain thousands of meters of clastic continental deposits, frequently intercalated with pyroclastic products from the western volcanic arc (Ramos 1999).…”

Section: Introductionmentioning

confidence: 99%

Magnetostratigraphy and paleomagnetism of early and middle Miocene synorogenic strata: basement partitioning and minor block rotation in Argentine broken foreland

Zambrano

Rapalini

Dávila

et al. 2010

Int J Earth Sci (Geol Rundsch)

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Magnetostratigraphic and paleomagnetic studies on early Andean synorogenic strata (Del Crestón Fm.), in the Famatina Belt (28.7°S, 67.5°W) clarify details of chronology that permit calculation of sedimentation rates within the broken foreland of west Argentina. The Del Crestón Fm represents the first record of broken foreland sedimentation within the southern Central Andean belt and the earliest retroarc volcanic rocks exposed several hundred kilometers from the trench. Twenty-five out of 49 sites collected along the succession presented a primary remanence, as determined through positive fold and reversal tests. Correlation of the local magnetic polarity section with the global polarity time scale indicates that the sedimentation of Del Crestón Fm started at *16.7 Ma and continued until *14.5 Ma. The youngest strata are represented by conglomerates bearing abundant Lower Paleozoic granite boulders indicating unroofing of the crystalline basement within the NW Sierras Pampeanas. This result supports the hypothesis of an early broken foreland stage at these latitudes of the Andes, with involvement of the basement in deformation and coeval retroarc volcanism, common attributes of flat-subduction regimes. A mean site paleomagnetic direction of Dec: 6.3°, Inc: -43.6°(a95: 8.0°, N = 24) confirm our earlier intrepretation that the central part of the Famatina Belt within the Sierras Pampeanas did not undergo large vertical axes rotations since the Middle Miocene.

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“…Likewise, most terrestrial sediments are deposited in association with active mountain belts, creating the additional challenge of deconvolving regional climatic signals from local tectonic-orographic signals. These issues are especially challenging in the south-central Andes where a regionally extensive climate transition in the latest Miocene (14, 27, 28) appears synchronous with significant tectonic uplift at this time (29)(30)(31)(32). It thus remains unclear whether the timing and extent of latest Miocene landscape ecologic changes in the south-central Andes were primarily controlled by tectonic-orographic effects or by globalscale changes in climate (e.g., refs.…”

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confidence: 99%

Mio-Pliocene aridity in the south-central Andes associated with Southern Hemisphere cold periods

Amidon

Fisher

Burbank

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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Although Earth’s climate history is best known through marine records, the corresponding continental climatic conditions drive the evolution of terrestrial life. Continental conditions during the latest Miocene are of particular interest because global faunal turnover is roughly synchronous with a period of global glaciation from ∼6.2–5.5 Ma and with the Messinian Salinity Crisis from ∼6.0–5.3 Ma. Despite the climatic and ecological significance of this period, the continental climatic conditions associated with it remain unclear. We address this question using erosion rates of ancient watersheds to constrain Mio-Pliocene climatic conditions in the south-central Andes near 30° S. Our results show two slowdowns in erosion rate, one from ∼6.1–5.2 Ma and another from 3.6 to 3.3 Ma, which we attribute to periods of continental aridity. This view is supported by synchrony with other regional proxies for aridity and with the timing of glacial ‟cold” periods as recorded by marine proxies, such as the M2 isotope excursion. We thus conclude that aridity in the south-central Andes is associated with cold periods at high southern latitudes, perhaps due to a northward migration of the Southern Hemisphere westerlies, which disrupted the South American Low Level Jet that delivers moisture to southeastern South America. Colder glacial periods, and possibly associated reductions in atmospheric CO2, thus seem to be an important driver of Mio-Pliocene ecological transitions in the central Andes. Finally, this study demonstrates that paleo-erosion rates can be a powerful proxy for ancient continental climates that lie beyond the reach of most lacustrine and glacial archives.

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Unsteady and spatially variable evolution of the Neogene Andean Bermejo foreland basin, Argentina

Cited by 116 publications

References 41 publications

Sedimentological and palynological constraints on the basal Triassic sequence in Central Switzerland

Sedimentological and palynological constraints on the basal Triassic sequence in Central Switzerland

Magnetostratigraphy and paleomagnetism of early and middle Miocene synorogenic strata: basement partitioning and minor block rotation in Argentine broken foreland

Mio-Pliocene aridity in the south-central Andes associated with Southern Hemisphere cold periods

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