New Data on the Late Quaternary Stratigraphy and Paleogeography of the Wijdefjorden Region (West Spitsbergen)

摘要

The World Ocean region with Spitsbergen Archipelago is one of the most indicative areas in terms of paleogeography for assessing global climatic fluctuations in the late Quaternary and for their long-term prediction. We carried out geomorphological, lithological, and faunal studies on the Wijdefjorden eastern coast in the southern Ny Frisland Peninsula (figure). A series of well-defined accumulative-abrasion marine terraces composed of sediments 2-5 m thick was revealed here within the Flatoyrdalen outwash valley springing from the Cookbreen outlet glacier (figure). Proterozoic bedrocks or Late Pleistocene sedimentary rocks occur in the terrace socle. The terraces differ slightly in height and include narrow (up to 200 m) benches complicated by beach ramparts up to 1 m high. Terrace edges are prominent. Benches are slightly inclined to the sea, rarely flat, and waterlogged in places. Terrace joints are partially veiled by solifluction sediments. Marine terraces are divided into the following levels (m): 4-5,10-12, 16, 18, 21-22, 25-28, 30-31, 42-45, and 65. Sediments of marine terraces comprise diverse and abundant microfauna assemblages. In terms of index species of mollusks, the marine terraces include the following assemblages: Astarte borealis and Serripes groenland-icus (up to 5 m); Mytilus edulis (5-12 m); Mya truncata and Hiatella arctica (12-65 m). The geodetic coordina- tion of the Quaternary reference section allowed precise recording of the altitudes for morphological elements of the terraces. A series of samples was collected on their surface and in sections for micro- and macro-fauna analyses. The absolute ages were established by radiocarbon dating based on Mya truncata shells and Balanus balanus loricae (table).