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Weaver, Barry L; Tarney, John; Saunders, Andrew D (1985): Geochemistry at DSDP Leg 82 Holes [dataset publication series]. PANGAEA, https://doi.org/10.1594/PANGAEA.805593, Supplement to: Weaver, BL et al. (1985): Geochemistry and mineralogy of basalts recovered from the Central North Atlantic. In: Bougault, H; Cande, SC; et al. (eds.), Initial Reports of the Deep Sea Drilling Project, Washington (U.S. Govt. Printing Office), 82, 395-419, https://doi.org/10.2973/dsdp.proc.82.119.1985

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Published: 1985 (exact date unknown) • DOI registered: 2013-02-21

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Abstract:
DSDP Leg 82 drilled nine sites to the southwest of the Azores Islands on the west flank of the Mid-Atlantic Ridge (MAR) in an attempt to determine the temporal and spatial evolution of the Azores "hot-spot" activity. The chemistry of the basalts recovered during Leg 82 is extremely varied: in Holes 558 and 561, both enriched (E-type: CeN/YbN = 1.5 to 2.7; Zr/Nb = 4.5 to 9.6) and depleted (or normal-N-type: CeN/YbN = 0.6 to 0.8; Zr/Nb > 20) mid-ocean ridge basalts (MORB) occur as intercalated lava flows. To the north of the Hayes Fracture Zone, there is little apparent systematic relationship between basalt chemistry and geographic position. However, to the south of the Hayes Fracture Zone, the chemical character of the basalts (N-type MORB) is more uniform. The coexistence of both E-type and N-type MORB in one hole may be explicable in terms of either complex melting/ fractionation processes during basalt genesis or chemically heterogeneous mantle sources. Significant variation in the ratios of strongly incompatible trace elements (e.g., La/Ta; Th/Ta) in the basalts of Holes 558 and 561 are not easily explicable by processes such as dynamic partial melting or open system crystal fractionation. Rather, the trace element data require that the basalts are ultimately derived from at least two chemically distinct mantle sources. The results from Leg 82 are equivocal in terms of the evolution of the Azores "hot spot," but would appear not to be compatible with a simple model of E-type MORB magmatism associated with upwelling mantle "blobs." Models that invoke a locally chemically heterogeneous mantle are best able to account for the small-scale variation in basalt chemistry.
Project(s):
Deep Sea Drilling Project (DSDP)
Coverage:
Median Latitude: 35.963341 * Median Longitude: -38.746699 * South-bound Latitude: 33.141500 * West-bound Longitude: -43.767300 * North-bound Latitude: 38.939700 * East-bound Longitude: -32.559700
Date/Time Start: 1981-09-22T00:00:00 * Date/Time End: 1981-10-28T00:00:00
License:
Creative Commons Attribution 3.0 Unported (CC-BY-3.0)
Size:
13 datasets

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Datasets listed in this publication series

  1. Weaver, BL; Tarney, J; Saunders, AD (1985): (Table 2) Geochemistry of magnesiochromite at DSDP Holes 82-556 and 82-562. https://doi.org/10.1594/PANGAEA.805580
  2. Weaver, BL; Tarney, J; Saunders, AD (1985): (Table 4) Major and trace element analyses of basalts and gabbro at DSDP Hole 82-556. https://doi.org/10.1594/PANGAEA.805582
  3. Weaver, BL; Tarney, J; Saunders, AD (1985): (Table 8) Major and trace elements at DSDP Hole 82-557 basalts. https://doi.org/10.1594/PANGAEA.805585
  4. Weaver, BL; Tarney, J; Saunders, AD (1985): (Table 9) Major and trace elements at DSDP Hole 82-558 basalts. https://doi.org/10.1594/PANGAEA.805586
  5. Weaver, BL; Tarney, J; Saunders, AD (1985): (Table 11) Major and trace elements at DSDP Hole 82-559 basalts. https://doi.org/10.1594/PANGAEA.805587
  6. Weaver, BL; Tarney, J; Saunders, AD (1985): (Table 12) Major and trace elements at DSDP Hole 82-561 basalts. https://doi.org/10.1594/PANGAEA.805588
  7. Weaver, BL; Tarney, J; Saunders, AD (1985): (Table 13) Major and trace elements at DSDP Hole 82-562 basalts. https://doi.org/10.1594/PANGAEA.805589
  8. Weaver, BL; Tarney, J; Saunders, AD (1985): (Table 14) Major and trace elements at DSDP Hole 82-563 basalts. https://doi.org/10.1594/PANGAEA.805591
  9. Weaver, BL; Tarney, J; Saunders, AD (1985): (Table 15) Major and trace elements at DSDP Hole 82-564 basalts. https://doi.org/10.1594/PANGAEA.805592
  10. Weaver, BL; Tarney, J; Saunders, AD (1985): (Table 3) Geochemistry of clinopyroxene and orthopyroxene at DSDP Holes 82-556, 82-557, and 82-563 gabbro. https://doi.org/10.1594/PANGAEA.805581
  11. Weaver, BL; Tarney, J; Saunders, AD (1985): (Table 6) Geochemistry of olivine microphenocrysts at DSDP Leg 82 Holes. https://doi.org/10.1594/PANGAEA.805584
  12. Weaver, BL; Tarney, J; Saunders, AD (1985): (Table 1) Geochemistry of plagioclase in DSDP Leg 82 Holes basalts. https://doi.org/10.1594/PANGAEA.805579
  13. Weaver, BL; Tarney, J; Saunders, AD (1985): (Table 5) Trace elements at DSDP Leg 82 Holes basalts. https://doi.org/10.1594/PANGAEA.805583