Continental Vertebrates During the Marine Isotope Stage 3 (MIS 3) in Argentina

Abstract

Paleontological sites in Argentina with continental vertebrates corresponding to the Marine Isotope Stage 3 (MIS 3) interval are scarce or poorly known. This situation is mainly due to the lack of absolute ages for Pleistocene fossil remains or their bearing sediments that would allow the verification of the chronology established for this interval. However, a few isolated evidences show that continental vertebrates responded to the abrupt temperature changes that characterized the MIS 3 (Heinrich colder events and Dansgaard-Oeschger warmer events). Up to date, continental vertebrate remains of this age have been found mainly in Buenos Aires province, but also in a few sites of northeastern Argentina (such as Entre Ríos, Corrientes, Formosa and Chaco provinces). In Buenos Aires province: (1) Paso Otero, in the Río Quequén Grande valley, evidence of warmer and more humid conditions were found in sediments dated in 37,800 ± 2300 radiocarbon years before present (RCYBP); (2) Mar del Sur, General Alvarado County, coastal marine sediments with continental mammals were dated in 25,700 ± 800 and 33,780 ± 1200 RCYBP;(3) Balneario Saldungaray, in the Río Sauce Grande valley, Tornquist County,

Last interglacial (MIS 5e) sea-level proxies in southeastern South America

“…Despite careful pretreatment of the shells from deposits suspected to be MIS 5 in age, the conventional radiocarbon method returned finite ages for pre-Holocene shells. The result of these finite dates led some authors to suggest the possibility of an MIS 3 sea-level highstand record along the Argentinian coast (Codignotto et al, 1988;González et al, 1988b;González, 1992;. González and Guida (1990) supported this interpretation through the use of magnetostratigraphy and correlating reverse magnetized stratigraphic units to magnetic excursions (see Sect.…”

“…Since the MIS 5 highstand more likely happened during MIS 5e and MIS 5d sea level was tens of meters below the present sea level (Lambeck and Chappell, 2001), either the magnetic measurements are in error or the deposit is not MIS 5e in age. González and Guida (1990) interpreted some deposits with anomalous magnetism that also had finite radiocarbon ages as being correlative to the Lake Mungo excursion. The Lake Mungo excursion was reported to have happened at about 30 ka, but recently this has been discredited (Roberts, 2008).…”

“…González et al (1986, 1988b) and González and Guida (1990) describe a Pleistocene estuary deposit in a location called Irazusta Quarry. The exact location is estimated based on a map from the paper but is likely over 100 km from the modern coast.…”

“…5.2.7), we infer it is MIS 5 in age. González et al (1988b) and González and Guida (1990) completed magnetostratigraphic analysis of the substrate upon which the platform surface was formed, a lagoon deposit. The reverse polarity of the sediments prompted correlation of the lagoon deposit with the Blake Excursion, a minor reversal during MIS 5d.…”

“…forming above mean sea level but influenced by seawater at least periodically). Gasparini et al (2016) reported a radiocarbon date from the beach-like deposit and, due to the sedimentary environment, considered it to be terrestrial limiting. An OSL date from the beach-like deposit gave a date of 60 ka (Beilinson et al, 2019), which also likely underestimates the true age.…”