Neotectonics in the South American passive margin: Evidence of Late Quaternary uplifting in the northern Paraiba Basin (NE Brazil)

Here we present an overview of speleothem δ18O records from South America, most of which are available in the Speleothem Isotopes Synthesis and Analysis (SISAL_v1) database. South American tropical and subtropical speleothem δ18O time series are primarily interpreted to reflect changes in precipitation amount, the amount effect, and consequently history of convection intensity variability of convergence zones such as the Intertropical Convergence Zone (ITCZ) and the South America Monsoon System (SAMS). We investigate past hydroclimate scenarios in South America related to the South American Monsoon System in three different time periods: Late Pleistocene, Holocene, and the last two millennia. Precession driven summertime insolation is the main driver of convective variability over the continent during the last 120 kyrs (from present day to 120 kyrs BP), including the Holocene. However, there is a dipole between speleothem δ18O records from western and eastern South America. Records located in the central region of Brazil are weakly affected by insolation-driven variability, and instead are more susceptible to the variability associated with the South Atlantic Convergence Zone (SACZ). Cold episodic events in the Northern Hemisphere, such as Heinrich and Bond Events, and the Little Ice Age, increase the convective activity of the SAMS, resulting in increased precipitation amount in South America.

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Grandes capturas fluviais no Brasil: síntese das novas descobertas

Estudos do Quaternário / Quaternary Studies ◽

10.30893/eq.v0i19.176 ◽

2019 ◽

pp. 23-31

Author(s):

André Augusto Rodrigues Salgado ◽

Luís Felipe Soares Cherem ◽

Michael Vinícius De Sordi

Keyword(s):

River Basins ◽

Passive Margin ◽

South American ◽

Drainage Network ◽

The South ◽

Base Level ◽

River Capture ◽

Determining Factors ◽

Major River

Capturas fluviais foram pouco investigadas no Brasil e apenas recentemente essa situação se alterou e sua ocorrência e feições correlatas foram sistematicamente estudadas para as grandes bacias fluviais não Amazônicas. Esse artigo sintetiza os principais resultados obtidos nos últimos cinco anos e apresenta a diversidade de magnitude e morfológica em seis capturas fluviais ao longo de quatro divisores entre as principais bacias hidrográficas do Brasil. Os resultados indicam que o nível de base, seguido da litoestrutura e da tectônica, constituem os fatores determinantes para ocorrência desses processos. Indicam ainda que as bacias hidrográficas atlânticas estão pirateando áreas das ditas continentais – Paraná e São Francisco – e que essa pirataria acelera o recuo erosivo do escarpamento da margem passiva sul-americana. Por fim, determinaram que as capturas causam a dissecação da rede de drenagem capturada, invertem o fluxo dos canais logo a jusante e, por fim, promovem o rebaixamento geral do relevo pirateado. Large fluvial captures in Brazil: synthesis of new discoveriesRiver captures have barely been studied in Brazil, and only recently the process and correlated features have been systematically studied for non-Amazonian major river basins. This paper synthesizes the main results obtained for the last five years and presents the diversity in magnitude and morphology of six river captures along the four divider of Brazilian-major river basins. The results indicate that the base level, followed by the lithostructure and tectonics, are the determining factors for the occurrence of these processes. They also indicate that the Atlantic basins are pirating areas of the continental ones - Paraná and São Francisco - and that this piracy accelerates the erosive retreat of the South American passive margin escarpment. Finally, they determined that the captures cause the dissection of the drainage network, invert the flow of the channels shortly downstream, and finally, promote the general lowering of the pirated relief. Keywords: River capture, Brazil, Major Basin Dividers, Fluvial Channel.

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A Quaternary record of the big-eyed bat Chiroderma villosum (Chiroptera: Phyllostomidae) with a revised lower molar terminology

Mammalia ◽

10.1515/mammalia-2017-0037 ◽

2018 ◽

Vol 82 (4) ◽

pp. 393-399 ◽

Cited By ~ 1

Author(s):

Guilherme S.T. Garbino ◽

Valéria da C. Tavares

Keyword(s):

South America ◽

Late Quaternary ◽

Northeastern Brazil ◽

South American ◽

The South ◽

Historical Interpretation ◽

Left Mandible ◽

Lower Molar

Abstract We report the first Quaternary record of the big-eyed bat Chiroderma villosum from South America based on a left mandible fragment collected in the Gruta dos Brejões, late Quaternary of northeastern Brazil. This material has been identified over the course of our revisionary work of the genus Chiroderma, including all species distributed in South America (Chiroderma doriae, Chiroderma salvini, Chiroderma trinitatum, Chiroderma villosum and Chiroderma vizottoi). Our results revealed that several characters of the second lower molar (m2), and of the posterior mandible may be used to identify and to diagnose the South American Chiroderma. We also revisited the historical interpretation of homologies of the lower molar cusps of Chiroderma, and propose a revised molar cusp terminology.

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(U-Th)/He Thermochronology and Zircon Radiation Damage in the South American Passive Margin: Thermal Overprint of the Paraná LIP?

Tectonics ◽

10.1029/2018tc005041 ◽

2018 ◽

Vol 37 (10) ◽

pp. 4068-4085 ◽

Cited By ~ 8

Author(s):

Mathias Hueck ◽

István Dunkl ◽

Beatrix Heller ◽

Miguel Angelo Stipp Basei ◽

Siegfried Siegesmund

Keyword(s):

Radiation Damage ◽

Passive Margin ◽

South American ◽

The South ◽

Thermal Overprint

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Phanerozoic low-temperature evolution of the Uruguayan Shield along the South American passive margin

Journal of the Geological Society ◽

10.1144/jgs2016-101 ◽

2017 ◽

Vol 174 (4) ◽

pp. 609-626 ◽

Cited By ~ 20

Author(s):

Mathias Hueck ◽

Sebastián Oriolo ◽

István Dunkl ◽

Klaus Wemmer ◽

Pedro Oyhantçabal ◽

...

Keyword(s):

Low Temperature ◽

Passive Margin ◽

Temperature Evolution ◽

South American ◽

The South

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Late Glacial-Holocene climatic transition record at the Argentinian Andean piedmont between 33–34° S

Climate of the Past Discussions ◽

10.5194/cpd-9-6125-2013 ◽

2013 ◽

Vol 9 (5) ◽

pp. 6125-6160

Author(s):

A. E. Mehl ◽

M. A. Zárate

Keyword(s):

Late Pleistocene ◽

Late Quaternary ◽

Late Glacial ◽

Early Holocene ◽

South American ◽

The South ◽

Sedimentary Sequences ◽

Aeolian Deposits ◽

Climatic Transition ◽

Flooding Events

Abstract. The Arroyo La Estacada (~33°28' S, 69°02' W), eastern Andean piedmont of Argentina, cuts through an extensive piedmont aggradational unit composed of a dominant late Pleistocene–early Holocene (LP–EH) alluvial sequence including several paleosols. The arroyo sedimentary record exhibits a paleosol developed affecting the topmost part of likely Lateglacial aeolian deposits aggraded into a floodplain environment by the end of the late Pleistocene. The paleosol shows variable grade of development in the outcrops along the arroyo probably in relation to fluvial valley paleotopography. Organic matter humification, carbonate accumulation and redox processes were the dominant processes associated with paleosol formation. By the early Holocene, when the formation of the paleosol ended, alluvial aggradation renewed and a higher frequency of flooding events could have affected the arroyo's floodplain environment. A period of relative landscape stability in the Arroyo La Estacada basin is inferred from the paleosol developed by the LP–EH transition in response to a climatic amelioration in the Andes cordillera piedmont after the Late Glacial arid conditions. The renewal of early Holocene alluvial aggradation was probably influenced by the South American Monsoon and resulted in a change in the sedimentary dynamics of the arroyo. The analyzed Late Glacial-Holocene alluvial record of the Andean piedmont constitutes a suitable record of the LP–EH climatic transition at the extra Andean region of Argentina. It is in agreement with regional paleoclimatic evidence along the southern tip of the South American continent, where other sedimentary sequences record similar late Quaternary paleoenvironmental changes over both fluvial and interfluvial areas.

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