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Laverne, Christine; Vanko, David A; Tartarotti, Paola; Alt, Jeffrey C (1995): Chemistry of secondary minerals from the deep sheeted dike complex of ODP Holes 137-504B and 140-504B [dataset publication series]. PANGAEA, https://doi.org/10.1594/PANGAEA.806586, Supplement to: Laverne, C et al. (1995): Chemistry and geothermometry of secondary minerals from the deep sheeted dike complex, Hole 504B. In: Erzinger, J; Becker, K; Dick, HJB; Stokking, LB (eds.), Proceedings of the Ocean Drilling Program, Scientific Results, College Station, TX (Ocean Drilling Program), 137, 167-189, https://doi.org/10.2973/odp.proc.sr.137140.014.1995

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Abstract:
Dolerites sampled from the lower sheeted dikes from Hole 504B during Ocean Drilling Program Legs 137 and 140, between 1562.4 and 2000.4 mbsf, were examined to document the mineralogy, petrography, and mineral parageneses associated with secondary alteration, to constrain the thermal history and composition of hydrothermal fluids. The main methods used were mineral chemical analyses by electron microprobe, X-ray diffraction, and cathodoluminescence microscopy. Temperatures of alteration were estimated on the basis of single and/or coexisting mineral chemistry.
Permeability is important in controlling the type and extent of alteration in the studied dike section. At the meter-scale, intervals of weakly altered dolerites containing fresh olivine are interpreted as having experienced restricted exposure to hydrothermal fluids. At the centimeter- or millimeter-scale, alteration patches and extensively altered halos adjacent to veins reflect the permeability related to intergranular primary porosity and cracks. Most of the sheeted dike alteration in this case resulted from non-focused, pervasive fluid-rock interaction.
This study confirms and extends the previous model for hydrothermal alteration at Hole 504B: hydrothermal alteration at the ridge axis followed by seawater recharge and off-axis alteration. The major new discoveries, all related to higher temperatures of alteration, are: (1) the presence of hydrothermal plagioclase (An80-95), (2) the presence of deuteric and/or hydrothermal diopside, and (3) the general increasing proportion of amphiboles, and particularly magnesio-hornblende with depth.
We propose that the dolerites at Hole 504B were altered in five stages. Stage 1 occurred at high temperatures (less than 500° to 700°C) and involved late-magmatic formation of Na- and Ti-rich diopside, the hydrothermal formation of Na, Ti-poor diopside and the hydrothermal formation of an assemblage of An-rich plagioclase + hornblende. Stage 2 occurred at lower temperatures (250°-320°C) and is characterized by the appearance of actinolite, chlorite, chlorite-smectite, and/or talc (in low permeability zones) and albite. During Stage 3, quartz and epidote precipitated from evolved hydrothermal fluids at temperatures between 310° and 320°C. Anhydrite appeared during Stage 4 and likely precipitated directly from heated seawater. Stage 5 occurred off-axis at low temperatures (250°C) with laumontite and prehnite from evolved fluids.
Project(s):
Ocean Drilling Program (ODP)
Coverage:
Latitude: 1.226900 * Longitude: -83.730300
Date/Time Start: 1991-04-07T13:10:00 * Date/Time End: 1991-11-12T04:10:00
License:
Creative Commons Attribution 3.0 Unported (CC-BY-3.0)
Size:
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Datasets listed in this publication series

  1. Laverne, C; Vanko, DA; Tartarotti, P et al. (1995): (Table 2) Representative amphibole analyses of ODP Holes 137-504B and 140-504B. https://doi.org/10.1594/PANGAEA.806574
  2. Laverne, C; Vanko, DA; Tartarotti, P et al. (1995): (Table 5) Representative chlorite and chlorite-smectite analyses of ODP Holes 137-504B and 140-504B. https://doi.org/10.1594/PANGAEA.806577
  3. Laverne, C; Vanko, DA; Tartarotti, P et al. (1995): (Table 1) Representative secondary clinopyroxene analyses of ODP Holes 137-504B and 140-504B. https://doi.org/10.1594/PANGAEA.806547
  4. Laverne, C; Vanko, DA; Tartarotti, P et al. (1995): (Table 6) Representative talc and mixed-layer talc-chlorite analyses of ODP Holes 137-504B and 140-504B. https://doi.org/10.1594/PANGAEA.806578
  5. Laverne, C; Vanko, DA; Tartarotti, P et al. (1995): (Table 10) Representative titanite analyses of ODP Holes 137-504B and 140-504B. https://doi.org/10.1594/PANGAEA.806585
  6. Laverne, C; Vanko, DA; Tartarotti, P et al. (1995): (Table 7) Representative epidote analyses of ODP Hole 140-504B. https://doi.org/10.1594/PANGAEA.806579
  7. Laverne, C; Vanko, DA; Tartarotti, P et al. (1995): (Table 9) Representative laumonite and heulandite analyses of ODP Hole 140-504B. https://doi.org/10.1594/PANGAEA.806584
  8. Laverne, C; Vanko, DA; Tartarotti, P et al. (1995): (Table 4) Representative plagioclase analyses of ODP Hole 140-504B. https://doi.org/10.1594/PANGAEA.806575
  9. Laverne, C; Vanko, DA; Tartarotti, P et al. (1995): (Table 8) Representative prehnite analyses of ODP Hole140-504B. https://doi.org/10.1594/PANGAEA.806583