Asymmetric distribution of displaced material in calcareous oozes around Great Meteor Seamount (North Atlantic)

• Main Authors: Stackelberg, Ulrich von, Rad, Ulrich von, Zobel, Barbara
• Format: Article in Journal/Newspaper
• Language: English
• Published: Bornträger 1976
• Subjects: Meteor Seamount; North Atlantic
• Online Access: https://oceanrep.geomar.de/id/eprint/56670/; https://oceanrep.geomar.de/id/eprint/56670/1/Stackelberg_Uv_1976_C.pdf

Sedimentological and biostratigraphic investigations of 15 cores (total length: 88 m) from the vicinity of Great Meteor Seamount (about 30° N, 28° W) showed that the calcareous oozes are asymmetricaly distributed around the seamount and vertically differentiated into two intervals. East and west of the seamount, the upper "A"-interval is characterized by yellowish-brown sediment colors and bioturbation; ash layers and diatoms are restricted to the eastern cores. On both seamount flanks, the sediments of the lower "B"-interval are white and very rich in CaC03 with a major fine silt (2-16 μ) mode (mainly coccoliths). Lamination, manganese micronodules, Tertiary foraminifera and discoasters, and small limestone and basalt fragments are typical of the "B"-interval of the eastern cores only. The sediments contain abundant displaced miaterial which was reworked from the upper parts of the seamount. The sedimentation around the seamount is strongly influenced by the kind of displaced material and the intensity of its differentiated dispersal: the sedimentation rates are generally higher on the east than on the west flank (e.g. in "B" : 0.9 cm/1000 y in the W; 3.1 cm/1000 y in the E), and lower for the "A" than for the "B"-interval. The lamination is explained by the combination of increased sedimentation rates with a strong input of material poor in organic carbon producing a hostile environment for benthic life. The CaC03 content of the cores is highly influenced by the proportion of displaced biogenous carbonate material (mainly coccoliths). The genuine in-situ conditions of the dissolution fades are only reflected by the minimum CaCOs values of the cores (Fig. 23; CCD = about 5,500 m; first bend in dissolution curve = 4,000 m; ACD = about 3,400 m). The preservation of the total foraminiferal association depends on the proportion of in-situ versus displaced specimens. In greater water depths (stronger dissolution), for example, the preservation can be improved by the admixture of relatively well preserved displaced ...