21. HEAVY MINERALS FROM PALEOGENE SEDIMENTS, DEEP SEA DRILLING PROJECT LEG 81: THEIR BEARING ON STRATIGRAPHY, SEDIMENT PROVENANCE, AND THE EVOLUTION OF THE NORTH ATLANTIC1

• Main Authors: Andrew C. Morton, British Geological Survey, Key Worth
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Greenland; Rockall Plateau
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.484.1124; http://www.deepseadrilling.org/81/volume/dsdp81_21.pdf

Five heavy mineral associations occur in the Paleocene and Eocene sediments recovered during Leg 81 of the Deep Sea Drilling Project (DSDP) in the SW Rockall area. Association 1, consisting of augite, iddingsite, and olivine, was derived from the basaltic rocks of the northern part of the Rockall Plateau. Association 2 consists of epidote group minerals, including piedmontite, and amphiboles of actinolite, actinolitic hornblende, and magnesio-hornblende com-positions, and was derived from the metamorphic basement of south Greenland. Association 3 comprises garnet, au-gite, apatite, and edenitic and pargasitic amphiboles and has a provenance in the southern Rockall Plateau. Associa-tions 4 (garnet, apatite, edenitic/pargasitic amphiboles) and 5 (garnet, apatite) are intrastratal solution derivatives of Association 3, with successive removal of first pyroxene and then amphibole with increasing depth of burial. Throughout the SW Rockall Plateau area there is a significant change in the spectrum of the above assemblages in the lower part of the Eocene. This change has been noted at Sites 403, 404, 553, and 555 and is defined by the last appear-ance of Association 2. This level therefore marks the cessation of sediment supply from southern Greenland and is the result of the final separation of Rockall and Greenland immediately prior to magnetic Anomaly 24.