Origin of massive ice at Cape Marre-Sale, Yamal Peninsula, Siberia, Russia: contrasting views
Abstract
The origin of permafrost and ground ice of the Cape Marre-Sale polar station area, Western Yamal Peninsula, Russia, has been debated for decades. This can be explained by the extremely complex morphology of sedimentary strata and cryofacies exposed along the costal bluffs. Here, we report massive ice observations realized during summer 2012 as well as numerous laboratory and field analysis previously conducted on the massive ice bodies and reported in the literature. Our objective is to present contrasting views currently being proposed to explain the origin of massive ice at Cape Marre-Sale. Several types of massive ice bodies can be observed along the exposures. One striking cryofacies observed shows alternating cm-thick ice lenses and cm-to-dm thick bands of sediment-rich ice, which are commonly folded with an amplitude of several meters. This very ice-rich cryofacies is interpreted either as buried basal ice of the Eurasian ice-sheet or alternatively as massive segregated ice formed during epigenetic permafrost aggradation. This cryofacies comprised meters large clasts of stratified sand with organics, with some of these stratifications being folded and faulted and showing boudinage structure. The location of these large sand clasts within the foliated ice-rich massive ice could be explained either by glacio-tectonic activity (glacio-dislocation during ice flow) or alternatively by regional tectonic activity. Large m-thick and meters-long pure ice bodies were also observed within the foliated massive ice. The first type is withish and contains a very large amount of air bubbles without any clear orientation. The second type is made of blueish to clear ice and contains a few air bubbles and rare, randomly distributed, fine-grained sediment inclusions suspended in the ice. Ice crystallography revealed the presence of large (cm) ice crystals in both types of ice. These pure ice bodies cross-cut the massive foliated ice. They could be interpreted as refrozen water trapped in intra-glacial tunnels formed within the basal ice (oxygen-rich water and suspension freezing of fine-grained sediments) of the ice-sheet or alternatively as groundwater injection (and subsequent refreezing) during freezing of taliks following lake drainage. Finally, wedge-shaped massive ice can also be observed near the top of the exposures. The first type is yellowish, vertically foliated, extends downward for several meters in the massive foliated ice and contains a significant amount of fine-grained sediment. This is either interpreted as Pleistocene ice wedge (frost-cracking) or alternatively as hydrolaccolith formed by the upward intrusion/expulsion of water within the foliated massive ice, likely due to the joint action of groundwater, permafrost aggradation and tectonic processes. The second type of wedge ice is withish in color and foliated and has been interpreted unanimously as Holocene ice wedges (frost-cracking). The contrasting views presented here represent new and reasonable working hypothesis to explain the genesis of massive ice at Cape Marre-Sale. These hypotheses have considerable implications for the reconstruction of paleoclimates and paleoenvironments of Western Siberia.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2012
- Bibcode:
- 2012AGUFM.C13A0605F
- Keywords:
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- 0702 CRYOSPHERE / Permafrost;
- 0710 CRYOSPHERE / Periglacial processes;
- 0726 CRYOSPHERE / Ice sheets;
- 0776 CRYOSPHERE / Glaciology