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Degree

MS, Kent State University, College of Arts and Sciences / Department of Geology, 2011.

Abstract

New analysis of USGS 70-92 taken in the Chukchi Sea at 69.95°, 165.367° during a previous investigation by the United States Geological Survey (USGS) indicates an ostracode record of terrestrial freshwater environments dated from around 13,000 – 11,000 ¹⁴C years BP (approximately 15,143 – 12,875 calendar years BP). This time frame corresponds to the Bølling/Allerød interstadial. This record is composed of four ostracode zones beginning at 12,640 ± 45 14C years BP (14,723 ± 93 calendar years BP) with fresh to slightly oligohaline fauna (Zone 1), including Holarctic species Pteroloxa cumuloidea and Candona rectangulata. This assemblage gives way to a freshwater habitat (< 1000 mg/l) ranging from ephemeral (Zone 2) to permanent (Zone 3) systems around ca 12,470 ± 45 14C years BP (14,419 ± 127 calendar years BP). Zone 2 includes Fabaeformiscandona rawsoni and Limnocythere inopinata. Zone 3 is dominated by Cytherissa lacustris and Candona candida and is relatively short-lived. This freshwater basin is subsequently in-filled and replaced by wetland peats, containing species of Cyclocypris and Cypria palustera. The final zone culminates in a marine transgression and is barren in terms of ostracodes. Of interest is that only the earliest zone (Zone 1) contains species which are exclusively found in the high Arctic today. Subsequent zones are characterized by freshwater species that occupy a range of temperatures that are commonly present in modern mid-latitude North America and Eurasia. Biogeography of these species drawn from modern ostracode distributions highlights the absence of high Arctic and polar fauna in Zones 2-4, suggesting that during the interval following Zone 1, temperature ranges were similar to modern sub-Arctic or mid-latitude temperature ranges. This conclusion is consistent with results from other works on pollen and plant macrofossil records for the region, and helps to narrow the time window in which fauna and humans would have been most likely to cross the Bering land bridge in late glacial time.

Subject Headings

Geological; Geology; Paleoecology

Keywords

Non-Marine Ostracodes; Beringia; Paleoecology; Late-Glacial; Lacustrine

Committee / Advisors

Alison Smith, PhD (Advisor)
Donald Palmer, PhD (Committee Member)
Joseph Ortiz, PhD (Committee Member)

Pages

133p.

Document number: kent1318855400
Permalink: http://rave.ohiolink.edu/etdc/view?acc_num=kent1318855400

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