Isotopic geochemistry of lavas at DSDP Holes 81-553 and 81-555 ...
It is demonstrated by K-Ar analyses that the age of reversely magnetized basalts, which immediately predate magnetic Anomaly 24B, is 53.5 ± 1.9 m.y. Samples from deep levels appear to be grossly contaminated by an extraneous argon component with a uniform argon-40/argon-36 ratio 440. This component...
| Main Authors: | , |
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| Format: | Article in Journal/Newspaper |
| Language: | English |
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PANGAEA
1984
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| Subjects: | |
| Online Access: | https://dx.doi.org/10.1594/pangaea.807006 https://doi.pangaea.de/10.1594/PANGAEA.807006 |
| Summary: | It is demonstrated by K-Ar analyses that the age of reversely magnetized basalts, which immediately predate magnetic Anomaly 24B, is 53.5 ± 1.9 m.y. Samples from deep levels appear to be grossly contaminated by an extraneous argon component with a uniform argon-40/argon-36 ratio 440. This component is thought to have been derived from fluids circulating in the lava pile during burial. The age result corroborates the assignment previously made to Anomaly 24B by Hailwood et al. (1979) and Lowrie and Alvarez (1981). It additionally suggests that lava extrusion formed part of a much larger magmatic event, which affected wide areas of the North Atlantic margins around the Paleocene/Eocene boundary, and can therefore probably be considered a good estimate of the age of this boundary. Initial 143Nd/144Nd ratios lie in the very restricted range 0.512920 ± 19 to 0.513026 ± 24 and initial 8 7Sr/86Sr ratios from ca. 0.703 to ca. 0.705. Acid leaching reduces the latter range to 0.70264 ± 4 to 0.70384 ± 4, suggesting ... : Supplement to: Macintyre, RM; Hamilton, P J (1984): Isotopic geochemistry of lavas from Sites 553 and 555. In: Roberts, DG; Schnittker, D; et al. (eds.), Initial Reports of the Deep Sea Drilling Project, Washington (U.S. Govt. Printing Office), 81, 775-781 ... |
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