Abstract
Abstract. The Arctic's glacial history has classically been interpreted from
marine records in terms of the fluctuations of the Eurasian and North
American ice sheets. However, the extent and timing of the East Siberian Ice
Sheet (ESIS) have remained uncertain. A recently discovered glacially
scoured cross-shelf trough extending to the edge of the continental shelf
north of the De Long Islands has provided additional evidence that glacial
ice existed on parts of the East Siberian Sea (ESS) during previous glacial
periods MIS 6 and 4. This study concentrates on defining the heavy mineral
signature of glacigenic deposits from the East Siberian continental margin
which were collected during the 2014 SWERUS-C3 expedition. The cores studied
are 20-GC1 from the East Siberian shelf, 23-GC1 and 24-GC1 from the De Long
Trough (DLT), and 29-GC1 from the southern Lomonosov Ridge (LR). Heavy
mineral assemblages were used to identify prominent parent rocks in
hinterland and other sediment source areas. The parent rock areas include
major eastern Siberian geological provinces such as the Omolon massif, the
Chukotka fold belt, the Verkhoyansk fold belt, and possibly the
Okhotsk–Chukotka volcanic belt. The primary riverine sources for the ESS
sediments are the Indigirka and Kolyma rivers, the material of which was glacially
eroded and re-deposited in the DLT. The higher abundances of amphiboles in
the heavy mineral assemblages may indicate ESS paleovalley of the Indigirka
River as a major pathway of sediments, while the Kolyma River paleovalley
pathway relates to a higher share of pyroxenes and epidote. The mineralogical
signature in the DLT diamicts, consisting predominantly of amphiboles and
pyroxenes with a minor content of garnet and epidote, shows clear delivery from
the eastern part of the ESIS. Although the physical properties of the DLT
glacial diamict closely resemble a pervasive diamict unit recovered from
the southern LR, their source material is slightly different. The
assemblages with elevated amphibole and garnet content, along with higher
titanite and ilmenite content of the southern LR ice-rafted diamict,
emphasise the Verkhoyansk fold belt as a possible primary source. The
presence of glacial sediments and the recovered glacial–tectonic features on the East Siberian continental shelf and slope, along with the results from this heavy mineral analysis, imply that glacial ice not only grew out
of the East Siberian shelf but also from the De Long Islands, and that
there was also ice rafting related sediment transportation to the southern
LR from westerly sources, such as the Laptev Sea.
Subject
Paleontology,Stratigraphy,Global and Planetary Change
Cited by
1 articles.
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