Abstract

This research addresses paleoclimatic variations using sedimentological, geochemical, and planktic foraminifera. The study was carried out in a survey core (ANP 1011) collected on the continental slope of the Icaraí Sub-basin (Ceará Basin), on the coast of the Municipality of Itapipoca, CE, Brazil. Particle size analysis, CaCO3 content, Ti/Ca and Fe/Ca ratios, and the analysis of foraminifera associations for biostratigraphic purposes were performed. Based on the relative abundance of planktic foraminifera, with indicators of warm and cold water throughout the studied cores, two biozones (Y: Upper Pleistocene and Z: Holocene), and two subzones (Z2 and Z1) were recognized. The data of sedimentological markers obtained confirmed the occurrence of more wet phases in northeastern Brazil during the early stages of the Holocene. The Ti/Ca and Fe/Ca ratios, as well as the geochemical and micropaleontological proxies, indicated a farther north displacement of the Intertropical Convergence Zone (ITCZ) in the Pleistocene–Holocene transition. This may have caused greater precipitation in the Northeastern region of Brazil, effectuating the entry of a high volume of terrestrial sediments directly into the ocean basin. Keywords: Quaternary biostratigraphy, marine sedimentation, ITCZ mobility, paleoclimate.

Highlights

  • Due to the fact that oceanic processes have been playing a major role in climate change in the history of the earth, it is necessary to understand the variations that have occurred in the ocean during the past to be able to understand and predict future climate changes

  • From the results obtained in the sedimentological, geochemical and micropaleontological analyzes of the ANP 1011 core collected from the continental slope of the Ceará Basin, it was possible to verify that the studied sedimentary section is composed of siliciclastic, silicibioclastic and biosiliciclastic sediments, deposited in a low intensity hydrodynamic regime

  • Through biostratigraphy data in planktic foraminifera, it was possible to characterize the section studied in two biozones (Y and Z) and two subzones (Z2 and Z1) of Pleistocene–Holocene age, with the limit between biozones Z and Y found at 82 cm

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Summary

Introduction

Due to the fact that oceanic processes have been playing a major role in climate change in the history of the earth, it is necessary to understand the variations that have occurred in the ocean during the past to be able to understand and predict future climate changes. Fluctuations in the formation of North Atlantic Deep Water at millennial-scale are related to the Heinrich, Dansgaard-Oeschger and Younger Dryas events (Maslin, 1995; Maslin et al, 2001; Elliot et al, 2002) These events are related to fluctuations in the Intertropical Convergence Zone (ITCZ) (Arz et al, 1998; 1999; Cruz et al, 2006; Wang et al, 2007), in addition to changes in the monsoon systems of South America and Asia (Cheng et al, 2009), and fluctuations in the Atlantic Meridional Overturn Circulation (AMOC) (Mcmanus et al, 2004; Weldeab et al, 2006)

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