Classification of Modern Marl Sediments in the Persian Gulf by Factor Analysis

Abstract

The marly bottom sediments in the northern half of the Persian Gulf were studied in 170 grab samples. Eighty two variables were catalogued for the gravel and sand fractions. Thirty eight of them were analyzed by comprehensive Q- and R-mode factor analysis in addition to previously evaluated conventional ratio plots (Sarnthein 1971). A cross-check evaluation of R- and Q-mode factor patterns allow the definition of a series of mappable facies units: benthos-poor calcitic clay (deep water), foram-mollusk-echinoderm marl (outer delta), foram-ostracod marl (delta axis), fine sandy calcareous marl (inner delta), molluskan coarse-grained marl (off-delta shelf plain), “relictiferous” coquina marl (shelf plain), large foramini-feral coquina arenite (banks), marly “relictiferous” coquina arenite (starved shelf). The main source of carbonate in these marls is terrigenous. Consequently in regions of high sedimentation (delta), the total carbonate content of the sediment is low because autochthonous biogenic carbonate and relict carbonate are diluted in these areas by high portions of lower carbonate material.