Different precipitation patterns across tropical South America during Heinrich and Dansgaard-Oeschger stadials

Zhang, Y; Chiessi, Cristiano Mazur; Mulitza, Stefan; Sawakuchi, André Oliveira; Häggi, Christoph; Zabel, Matthias; Portilho-Ramos, Rodrigo Costa; Schefuß, Enno; Crivellari, Stefano; Wefer, Gerold

doi:10.1016/j.quascirev.2017.10.012

Cited by 54 publications

(56 citation statements)

References 70 publications

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“…Similarly, the YD is recorded as a significant negative excursion in terrestrial δ 18 O records from both speleothems in Peru (Cheng et al, 2013) and southeast Brazil (Cruz et al, 2005;Wang et al, 2007), as well as in ice cores in Peru and Bolivia (Thompson et al, 1995;Ramirez et al, 2003) and high Altiplano lake levels . Collectively, these palaeoclimate records indicate wetter conditions in the Central Andes during Heinrich Stadials and the YD, associated with cold events in the North Atlantic, southward displacement of the ITCZ and strengthening of the SASM (Mosblech et al, 2012;Novello et al, 2017;Zhang et al, 2017;Crivellari et al, 2018).…”

Section: Modern and Past Climatementioning

confidence: 86%

Timing of past glaciation at the Sierra de Aconquija, northwestern Argentina, and throughout the Central Andes

D’Arcy

Schildgen

Strecker

et al. 2019

Quaternary Science Reviews

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Advances in cosmogenic nuclide exposure dating have made moraines valuable terrestrial recorders of palaeoclimate. A growing number of moraine chronologies reported from the Central Andes show that tropical glaciers responded sensitively to past changes in precipitation and temperature over timescales ranging from 10 3 to 10 5 years. However, the causes of past glaciation in the Central Andes remain uncertain. Explanations have invoked insolation-modulated variability in the strength of the South American Summer Monsoon, teleconnections with the North Atlantic Ocean, and/or cooling in the Southern Hemisphere.The driver for these past climate changes is difficult to identify, partly due to a lack of dated moraine records, especially in climatically sensitive areas of the southern Central Andes.Moreover, new constraints are needed on precisely where and when glaciers advanced. We use cosmogenic 10 Be produced in situ to determine exposure ages for three generations of moraines at the Sierra de Aconquija, situated at 27°S on the eastern flank of the southern Central Andes. These moraines record glacier advances at approximately 22 ka and 40 ka, coincident with summer insolation maxima in the sub-tropics of the Southern Hemisphere, as well as at 12.5 ka and 13.5 ka during the Younger Dryas and the Antarctic Cold Reversal, respectively. We also identify minor glaciation during Bond Event 5, also known as the 8.2 ka event. These moraines register past climate changes with high fidelity, and currently constitute the southernmost dated record of glaciation on the eastern flank of the Central Andes. To contextualise these results, we compile 10 Be data reported from 144 moraines in the eastern Central Andes that represent past glacier advances. We re-calculate exposure ages from these data using an updated reference production rate, and we re-interpret the moraine ages by taking the oldest clustered boulder age (after the exclusion of outliers attributed to nuclide inheritance) as closest to the timing of glacier advance-an approach for which we provide empirical justification. This compilation reveals that Central Andean glaciers have responded to changes in temperature and precipitation. We identify cross-latitude advances in phase with insolation cycles, the last global glacial maximum, and episodes of strengthened monsoonal moisture transport including the Younger Dryas and Heinrich Stadials 1 and 2. Our results from the Sierra de Aconquija allow us to constrain the southerly limit of enhanced precipitation associated with Heinrich Stadials at ~25°S. More broadly, our findings demonstrate at both local and regional scales that moraines record past climate variability with a fine spatial and temporal resolution.3

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Section: Modern and Past Climatementioning

confidence: 86%

Timing of past glaciation at the Sierra de Aconquija, northwestern Argentina, and throughout the Central Andes

D’Arcy

Schildgen

Strecker

et al. 2019

Quaternary Science Reviews

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“…For the lower part of core GL‐1248 (6.30‐ to 16.66‐m core depth; ≈44–129 ka), the chronology was derived from the alignment of the Ti/Ca record of core GL‐1248 to the ice δ 18 O (Figure ) record of the North Greenland Ice Core Project (NGRIP) using the extended Greenland Ice Core Chronology (GICC05modelext) (NGIRP members, ; Wolff et al, ). The underlying assumption to this alignment is that Greenland stadials are associated with increased precipitation over northeastern Brazil and increased delivery of terrigenous material to the western equatorial Atlantic, as supported by speleothem and marine records of the last glacial period (e.g., Jaeschke et al, ; Wang et al, ; Zhang et al, ). Thus, the major Ti/Ca fluctuations of core GL‐1248 were matched with the major changes in δ 18 O from the NGRIP record, with tie points being mostly located at the midpoint of abrupt excursions on both records.…”

Section: Methodsmentioning

confidence: 98%

“…Paleoceanography and Paleoclimatology (NGIRP members, 2004;Wolff et al, 2010). The underlying assumption to this alignment is that Greenland stadials are associated with increased precipitation over northeastern Brazil and increased delivery of terrigenous material to the western equatorial Atlantic, as supported by speleothem and marine records of the last glacial period (e.g., Jaeschke et al, 2007;Wang et al, 2004;Zhang et al, 2017). Thus, the major Ti/Ca fluctuations of core GL-1248 were matched with the major changes in δ 18 O from the NGRIP record, with tie points being mostly located at the midpoint of abrupt excursions on both records.…”

Section: 1029/2018pa003437mentioning

confidence: 99%

Millennial‐ to Orbital‐Scale Responses of Western Equatorial Atlantic Thermocline Depth to Changes in the Trade Wind System Since the Last Interglacial

Venancio

Mulitza

Govin

et al. 2018

Paleoceanog and Paleoclimatol

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Surface ocean circulation in the western equatorial Atlantic is mainly wind driven and plays a major role for the transport of warm waters to the North Atlantic. Past changes in the strength and direction of the trade winds are well documented, but the response of the western equatorial Atlantic circulation and water column structure to these changes is unclear. Here we used the difference between the stable isotopic oxygen composition of two species of planktonic foraminifera (Globigerinoides ruber white and Neogloboquadrina dutertrei) from two sediment cores collected off northeastern Brazil to investigate millennial‐ and orbital‐scale changes in upper ocean stratification since the Last Interglacial. Our records indicate enhanced upper ocean stratification during several Heinrich stadials, partly due to a shoaling of the thermocline, which was linked to a decrease in the strength of southeast trades winds. In addition, we show that a decrease in wind zonality induced by increases in Northern Hemisphere low‐latitude summer insolation causes a shoaling of the thermocline in the western equatorial Atlantic. These ocean‐atmosphere changes contributed to a reduction in the cross‐equatorial transport of warm waters, particularly during Heinrich stadials and Marine Isotope Stage 4.

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“…Botanical material was collected in Mazagão city-Amapá, Brazil (00 • The seeds were collected in two periods, according to Amazon seasonality [76,77]. The first collection was performed on the tenth day of March (AO1) and the second on the tenth day of the month of June (AO2) in the same place.…”

Section: Plant Materials and Oil Extraction Of Carapa Guianensismentioning

confidence: 99%

Fatty Acid Amides Synthesized from Andiroba Oil (Carapa guianensis Aublet.) Exhibit Anticonvulsant Action with Modulation on GABA-A Receptor in Mice: A Putative Therapeutic Option

et al. 2020

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Epilepsy is a chronic neurological disease characterized by excessive neuronal activity leading to seizure; about 30% of affected patients suffer from the refractory and pharmacoresistant form of the disease. The anticonvulsant drugs currently used for seizure control are associated with adverse reactions, making it important to search for more effective drugs with fewer adverse reactions. There is increasing evidence that endocannabinoids can pharmacologically modulate action against seizure and antiepileptic disorders. Therefore, the objective of this study is to investigate the anticonvulsant effects of fatty acid amides (FAAs) in a pentylenetetrazole (PTZ)-induced seizure model in mice. FAAs (FAA1 and FAA2) are obtained from Carapa guianensis oil by biocatalysis and are characterized by Fourier Transform Infrared Analysis (FT-IR) and Gas Chromatography-Mass Spectrometry (GC-MS). Only FAA1 is effective in controlling the increased latency time of the first myoclonic jerk and in significantly decreasing the total duration of tonic-clonic seizures relative to the pentylenetetrazol model. Also, electrocortical alterations produced by pentylenetetrazol are reduced when treated by FAA1 that subsequently decreased wave amplitude and energy in Beta rhythm. The anticonvulsant effects of FAA1 are reversed by flumazenil, a benzodiazepine antagonist on Gamma-Aminobutyric Acid-A (GABA-A) receptors, indicating a mode of action via the benzodiazepine site of these receptors. To conclude, the FAA obtained from C. guianensis oil is promising against PTZ-induced seizures.

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Different precipitation patterns across tropical South America during Heinrich and Dansgaard-Oeschger stadials

Cited by 54 publications

References 70 publications

Timing of past glaciation at the Sierra de Aconquija, northwestern Argentina, and throughout the Central Andes

Timing of past glaciation at the Sierra de Aconquija, northwestern Argentina, and throughout the Central Andes

Millennial‐ to Orbital‐Scale Responses of Western Equatorial Atlantic Thermocline Depth to Changes in the Trade Wind System Since the Last Interglacial

Fatty Acid Amides Synthesized from Andiroba Oil (Carapa guianensis Aublet.) Exhibit Anticonvulsant Action with Modulation on GABA-A Receptor in Mice: A Putative Therapeutic Option

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