Climate changes in Northeastern Brazil from deglacial to Meghalayan periods and related environmental impacts

doi:10.1016/j.quascirev.2020.106655

Quaternary Science Reviews

Volume 250, 15 December 2020, 106655

https://doi.org/10.1016/j.quascirev.2020.106655 Get rights and content

Highlights

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The combined use of speleothem δ¹⁸O, δ¹³C and ⁸⁷Sr/⁸⁶Sr records for paleoenvironmental reconstruction.
•
Relative changes in soil turnover in response to ITCZ rainfall in Northeastern Brazil.
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Evidences of hydrological changes in the ITCZ region from multiproxy cave records.
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Increased aridification in Northeastern Brazil coincident with Meghalayan chronozone.
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The 4.2 event as marker of abrupt changes in climate and its impact in human population.

Abstract

Changes in insolation driven by precession and obliquity are considered the major driver of tropical precipitation on orbital time scales, and responsible for vegetation and physical landscape changes during the Late Holocene over tropical South America. Here we investigate the environmental changes in the karst region of Chapada do Apodi - Northeastern Brazil (NEB), using a multi-proxy approach including carbon (δ¹³C), oxygen (δ¹⁸O) and strontium (⁸⁷Sr/⁸⁶Sr) isotopic analyses on speleothems from different caves, carbonate bedrock, and clastic cave deposits. This approach reveals that the balance between soil formation and erosion and their alternating impact on vegetation and precipitation changes occurred in response to variations in the position and intensity of the Intertropical Convergence Zone (ITCZ) over the region. The high δ¹³C and δ¹⁸O and low ⁸⁷Sr/⁸⁶Sr values at 4,200 yrs BP indicate a massive episode of soil erosion, resulting in the exposure of carbonate bedrocks over a large area of the karst terrain. This event marks the beginning of the Meghalayan chronozone, characterized as the aridification of this region, decline in soil production, drying out of underground drainages, and increased dominance of dry-adapted flora species, characteristic of a more open vegetation (caatinga). We investigated if the Holocene climatic changes affected human occupation in the NEB and found that the overall demographic course is virtually identical to the well-established curve characterized by population deflation during Middle Holocene.

Section snippets

Authors statement

Giselle Utida: Conceptualization, Methodology, Formal analysis, Investigation, Writing - original draft. Francisco W. Cruz: Conceptualization, Methodology, Writing - original draft, Supervision, Funding acquisition. Roberto V. Santos: Resources, Writing - review & editing, Supervision. André O. Sawakuchi: Resources, Writing - review & editing, Supervision. Nicolas M. Stríkis: Writing - review & editing. Valdir F. Novello: Writing - review & editing. Hong Wang: Resources, Writing - review &

Regional settings

The study area is located in the Rio Grande do Norte State, a region at the edge of NEB (Fig. 1). The annual mean temperature is around 28 °C (INMET - National Institute of Meteorology – Instituto Nacional de Meteorologia – data from 1961 to 1990). Average precipitation is approximately 730 mm/year and it is concentrated in the period when the ITCZ migrates to the south, between March and May with ca. 150 mm for this period (Fig. 1a) (Agência Nacional de Águas – ANA - National Agency of Waters,

Materials and methods

This research explores a wide variety of materials such as speleothems, clastic sediments, soil, limestone bedrock and guano deposits from the same region. The chronology is based on U/Th in speleothems, optically stimulated luminescence in clastic sediments and radiocarbon dating in the guano deposits. All the methods and related applications are described below.

Speleothem description

The composite speleothem data from NEB extends back to 25,700 yrs BP with speleothems RN4, Abissal and Ale-1, all dated by Cruz et al. (2009). Except for the period from 15,100 to 13,200 yrs BP, the combination of these stalagmites provides a continuous isotopic record from 25,700 to 4,100 yrs BP (Table 1) with an average resolution of 25 yrs.

The TRA7 speleothem covers part of the last 5,000 yrs. It shows a hiatus between 4,100 and 2,250 yrs BP. The speleothem deposition is apparently

Climatic and environmental reconstruction

The isotopic composition of rainfall in this sector of NEB is interpreted as primarily influenced by the amount of precipitation with a decrease (increase) in δ¹⁸O and δD corresponding to enhanced (weakened) ITCZ rainfall on interannual and seasonal timescales forced by insolation (Fig. 1a, record # 2–3, 4b, 4h) (Cruz et al., 2009; Mulitza et al., 2017; Utida et al., 2019). Thus, speleothem δ¹⁸O records at the study site can be used to reconstruct environmental changes that are associated with

Conclusion

Our multi-proxy study from Chapada do Apodi shows contrasting environmental and paleoclimatic conditions during the Meghalayan period when compared with the previous period, from ∼11,000 to 4,200 yrs BP. The first period was characterized by denser vegetation (predominance of savanna), higher rainfall amounts and thicker soil cover above the cave system, while the Meghalayan period is marked in NEB by a decreased rainfall amount, sparse vegetation (predominance of caatinga) and reduced soil

Authors contributions

G.U. and F.W.C designed the experiment, performed isotopic analysis and prepared the manuscript with help from the co-authors; F.W.C. directed the project; R.V.S. coordinated the laboratory procedures for strontium isotope analysis; A.O.S., N.M.S. and V.F.N. contributed with the paleoclimate interpretations; H.W. and L.C.R.P. helped with the radiocarbon dating; M.V. helped with the interpretation and revision of the manuscript; A.S. and A.C.B. helped with archaeological data compilation and

Data availability

The dataset generated as part of this study will be available in the PANGAEA.

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgments

We thank Christian Millo, Alyne Barros M. Lopes and Osmar Antunes (LES-IGc-USP, Brazil), and Luiz Mancini (LAIS-IGc-UNB, Brazil) for their support during the analyses, André Zular (IGc-USP, Brazil) for support during the field trip and grain-size analysis, Johan Etourneau (Université de Bordeaux, France) for comments about this paper. We are grateful to Leda Zogbi for the Trapiá cave map and to Professor Dr. Francisco Hilário Bezerra (UFRN, Brazil) and A.N.P., Brazil for aerial images, and

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Climate changes in Northeastern Brazil from deglacial to Meghalayan periods and related environmental impacts

Highlights

Abstract

Section snippets

Authors statement

Regional settings

Materials and methods

Speleothem description

Climatic and environmental reconstruction

Conclusion

Authors contributions

Data availability

Declaration of competing interest

Acknowledgments

Quat. Res.

Chem. Geol.

Earth Sci. Rev.

Quat. Sci. Rev.

Quat. Sci. Rev.

Appl. Geogr.

Quat. Geochronol.

Quat. Int.

Rev. Palaeobot. Palynol.

Quat. Int.

Earth Planet. Sci. Lett. 371–

Quat. Sci. Rev.

Palaeogeogr. Palaeoclimatol. Palaeoecol.

Quat. Sci. Rev.

Geochem. Cosmochim. Acta

Chem. Geol.

Earth Sci. Rev.

Chem. Geol.

Earth Planet Sci. Lett.

Geomorphology

Geochem. Cosmochim. Acta

Chem. Geol.

Earth Planet Sci. Lett.

Sediment. Geol.

Quat. Sci. Rev.

Palaeogeogr. Palaeoclimatol. Palaeoecol.

Quat. Sci. Rev.

Geochem. Cosmochim. Acta

Geochem. Cosmochim. Acta

J.Archaeo. Sci.: Report

Earth Planet Sci. Lett.

O domínio morfoclimático semi-árido das Caatingas brasileiras

Geomorfologia

An Introduction to Optical Dating

Abrupt climate change

Science

Sistema Nacional de Informações sobre Recursos Hídricos

Programa Geologia do Brasil – PGB. Projeto Geologia e Recursos Minerais do Estado do Rio Grande do Norte. Mapa geológico do Estado do Rio Grande do Norte. Escala. 1:500.000. Recife: CPRM/FAPERN. 1 mapa color

The deglacial history of the western tropical Atlantic as inferred from high resolution stable isotope records off northeastern Brazil

Earth Planet Sci. Lett.

Petrography, strontium, barium and uranium concentrations, and strontium and uranium isotope ratios in speleothems as palaeoclimatic proxies: soreq Cave, Israel

Holocene

Mapeamento, caracterização ambiental e relevância do patrimônio espeleológico de Felipe Guerra/RN

An abrupt shift in the Indian monsoon 4000 years ago

Geophys. Monogr.

Fracturing and fluid-flow during post-rift subsidence in carbonates of the jandaıra formation, Potiguar Basin, NE Brazil

Basin Res.

The 4.2 kaBP Event in the Mediterranean region: an overview

Clim. Past

A pervasive millennial-scale cycle in north atlantic Holocene and glacial climates

Science

A severe centennial-scale drought in midcontinental North America 4200 years ago and apparent global linkages

Holocene

Monsoon response to changes in Earth’s orbital parameters: comparisons between simulations of the Eemian and of the Holocene

Clim. Past

COnstructing proxy records from age models (COPRA)

Clim. Past

A 780-year annually resolved record of Indian Ocean monsoon precipitation from a speleothem from south Oman

J. Geophys. Res.

Climatic fluctuations influence the genesis and diagenesis of carbonate speleothems in southwestern France

Natl. Speleo. Soc. Bull.

Climate change patterns in Amazonia and biodiversity

Nat. Commun.

The climate variability in northern Levant over the past 20,000 years

Geophys. Res. Lett.