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Marine Geology Repository

Cara Fritz

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ANDRILL location

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84m of ice

850m of ocean water

1,285m drill core

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Note the sea level in the row of images below. As the ice sheet increases the sea level drops.

These images show what the land surface cover would have looked like in each case.

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Mudstone is deposited by ocean currents that transport fine-grained silt and clay. There are no diatoms because this layer is deposited under the ice shelf and the overlying ocean does not have direct contact with sunlight. There are no clasts (rocks) because the rocks in the ice shelf have already melted out and fallen to the sea floor closer to the ice sheet. Where in the picture will this layer be created?

Sediment rate = slow

Box 90 (172-174 m)

Mudstone

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Diatomite is composed of the remains of diatoms, whose silica shells (SiO2) make up the layers of this sediment. Diatoms are single celled algae found all over the world in hundreds of species and varieties. Diatom species are temperature sensitive, so their presence is a clue to past ocean temperatures. Where diatomite is deposited, the ocean is open to the atmosphere and sunlight (not covered by sea ice) so these organisms can thrive. Where in the picture will this layer be created?

Sediment rate = slowest

Box 82 (154-156 m)

Diatomite

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Diamictite is composed of coarse, angular and well-rounded clasts (rocks) of many types, embedded in a mixture of mud. It is described as poorly sorted. Diamictite is created in subglacial environments, meaning that it is deposited under the ice sheet where the ice meets the land. The clasts and sand grains may show evidence of breakage and rolling. Where in the picture will this layer be created?

Sediment rate = fast

Box 79 (148-150 m)

Diamictite

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massive diamictite

diamictite & intraclastic mudchip breccia

ice shelf

Glacial till

ice shelf

Glacial till

ROV images