Modern Benthic Foraminifera off Novaya Zemlya Tidewater Glaciers, Russian Arctic

Abstract

Living and dead foraminifera have been investigated along three transects away from tidewater glaciers of northern Novaya Zemlya. There are three glacier-proximal dominant foraminiferal taxa: Allogromiina (unidentified species), Elphidium excavatum f. clavata, and Cassidulina reniforme. In this environment the sediment consists of ice-front diamicton (0.17 km from the terminus) and massive glaciomarine clay (0.2 to 7 km). Allogromiids dominate the low-diverse fauna closest to the glacier outlet, followed by E. e. clavata. Diagenetic decay of the allogromiid tests will result in the preservation of an E. e. clavata dominated fossil assemblage. The occurrence of C. reniforme increases with nutrient enrichment reflected in phytoplankton abundance and sediment C_org content. The C. reniforme/E. e. clavatum-ratio exceeds 50% in locations where glacial impact is moderate as marked by the absence of glacial-cooled surface water and low concentrations of suspended sediment. The presence of Quinqueloculina stalkeri is specific to the glaciomarine clay.

Islandiella norcrossi is abundant in distal stations (7 to 22 km from the glacier termini) in distal glaciomarine sediments enriched with ice rafted debris and in marine mud. A Nonionellina labradorica peak is also characteristic of glacial-distal habitats. The frequency of Cibicides lobatulus and other attached forms correlates with the abundance of clasts and shows no relation to water depth as the hard substrate is primarily ice rafted. Larger foraminifera (Saccorhiza ramosa and others) occur only in the marine mud. Numbers of living foraminifera and macrofauna biomass vary likewise, and remain unexplained by the measured physical parameters. Dissolution of calcareous tests, ubiquitous on the adjacent shelf, occurs only in distal, oxidized sediments.