Javed Iqbal
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M. Sc. Thesis
Sedimentology and Distribution of Benthonic Foraminifera in McClure Strait.
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M’Clure Strait is one of the main interisland channels in the Canadian Arctic Archipelago. These channels owe their origin to a pre-Pleistocene fluvial drainage system which was modified by the Pleistocene glaciers and subsequently inundated as these glaciers retreated.
Recent benthonic foraminifera in the M’Clure Strait have been studied from 40 grab samples. The foraminiferal assemblage is essentially similar to those reported from the adjacent areas of the Eastern Arctic. Distinct North Atlantic (sub-arctic) affinities are also apparent. A total of 74 species belonging to 48 genera and 27 families have been identified, described and illustrated. Of these 57 species are calcareous and the remaining 17 are arenaceous. Predominant species are: Saccammina sphaerica, Cribrostomoides subglobosus, Trochammina nana, Trochammina quadriloba, Cibicides lobatulus, Islandiella teretis, Islandiella norcorssi, and Islandiella islandica.
The Rose Bengal staining technique gave very ambiguous results and it was not possible to distinguish living specimens with confidence. Consequently, the entire population has been treated as a thanatocoenose.
Sedimentary analysis of 36 samples reveals that the Recent sediments in M’Clure Strait are predominantly muds and clays with small amounts of coarse material (sand and gravel) occurring in a random distribution irrespective of depth and distance from shore. This is considered to be the result of extensive ice-rafting, which is the dominant mode of sediment transportation in the area.
The environmental parameters studied to evaluate and correlate the associated foraminiferal distribution were: bathymetry, sediment distribution, temperature and salinity. Visual analysis failed to correlate the random and patchy distribution patterns of the predominant species with these environmental parameters. Only very broad generalizations permit the grouping of the fauna into (a) Calcareous, (b) Arenaceous, and (c) Mixed. Total population appears to be the result of faunal mixing caused by extensive ice-rafting, winnowing and current activity.
The application of Factor Analysis brings out three definite faunal assemblages (or thanatotopes) based on such factors as depth, distance from shore, nature of the substrate and test composition. Thanatotope I is exclusively arenaceous, decreases away from shore and shows some preference for fine-grained substrates. The indicator species for this assemblage are: Cribrostomoides crassimargo, Saccorhiza ramosa, Textularia earlandi and genus Trochammina. Thanatotope II is predominantly calcareous, increases away from shore and is found in silt and sandy silt substrates. The indicator species for this assemblage are: Astrononion gallowayi, Cibicides lobatulus, Cassidella complanata, Eponides tener, Fissurina semimarginata, Hyperammina elongata genus Islandiella, Lagena laevis, Oolina hexagona, Planispirinoides bucculentus, Quinqueloculina seminulum and Triloculina trihedra. Thanatotope III is a mixture of calcareous and arenaceous species which agree in their consistent occurrence in all types of sediments, from clay to gravelly sand, and almost universal occurrence in their areal distribution. The indicator species for this assemblage are: Buccella frigida, Cibicides lobatulus, Cribrostromoides subglobosus, Elphidium bartletti, genus Islandiella, Lagena meridionalis, Melonis zaandami, Nonionella auricula, genus Reophax, and Saccammina sphaerica.
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Supervisor: Franco Medioli / C. T. Schafer