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Titolo:
SURFACE TEXTURAL ANALYSIS OF QUARTZ SAND GRAINS FROM ODP SITE-918 OFFTHE SOUTHEAST COAST OF GREENLAND SUGGESTS GLACIATION OF SOUTHERN GREENLAND AT 11 MA
Autore:
HELLAND PE; HOLMES MA;
Indirizzi:
UNIV NEBRASKA,DEPT GEOL 214,BESSEY HALL LINCOLN NE 68588 UNIV NEBRASKA,DEPT GEOL 214 LINCOLN NE 68588
Titolo Testata:
Palaeogeography, palaeoclimatology, palaeoecology
fascicolo: 1-4, volume: 135, anno: 1997,
pagine: 109 - 121
SICI:
0031-0182(1997)135:1-4<109:STAOQS>2.0.ZU;2-U
Fonte:
ISI
Lingua:
ENG
Keywords:
LATE MIOCENE; GLACIOMARINE; ICE RAFTING; QUARTZ SAND; SURFACE TEXTURES; NORTH ATLANTIC;
Tipo documento:
Article
Natura:
Periodico
Citazioni:
31
Recensione:
Indirizzi per estratti:
Citazione:
P.E. Helland e M.A. Holmes, "SURFACE TEXTURAL ANALYSIS OF QUARTZ SAND GRAINS FROM ODP SITE-918 OFFTHE SOUTHEAST COAST OF GREENLAND SUGGESTS GLACIATION OF SOUTHERN GREENLAND AT 11 MA", Palaeogeography, palaeoclimatology, palaeoecology, 135(1-4), 1997, pp. 109-121

Abstract

Shipboard analysis of the 1183-m sedimentary section recovered at Site 918 in the Irminger Basin during Ocean Drilling Program Leg 152 revealed material of glacial origin (diamictons, ice-rafted debris (IRD) and dropstones) as deep as 543 m below sea floor (bsf). The sediment containing the deepest dropstone was biostratigraphically dated shipboard as approximately 7 Ma, pushing back the date for the onset of glaciation on southern Greenland by 5 Ma. Thin layers of fine sand were found as much as 60 m deeper in the core, raising the possibility of an even earlier date for glaciation. To determine the sedimentary history of these deeper sand layers, the surface textures on quartz grains fromeleven cores bracketing the interval of interest were analyzed by scanning electron microscope. The results suggest that the grains in the 60-m interval below the deepest dropstone have a glacial history. At that level, an Ii-Ma Sr-isotope date was obtained from planktonic foraminifers. This late Miocene timing is supported biostratigraphically byboth nannofossil and foraminifer assemblages, indicating a new minimum age for the onset of glaciation on southern Greenland and in the North Atlantic. (C) 1997 Elsevier Science B.V.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 25/09/20 alle ore 00:28:34