Peterson, Curt; Duncan, Robert A; Scheidegger, Kenneth F (1986): Minerals and geochemistry abundance and occurance, as well as K-Ar determinations for DSDP Site 92-597 basalts [dataset publication series]. PANGAEA, https://doi.org/10.1594/PANGAEA.792591, Supplement to: Peterson, C et al. (1986): Sequence and longevity of basalt alteration at Deep Sea Drilling Project Site 597. In: Leinen, M; Rea DK; et al. (eds.), Initial Reports of the Deep Sea Drilling Project, Washington (U.S. Govt. Printing Office), 92, 505-515, https://doi.org/10.2973/dsdp.proc.92.132.1986
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Abstract:
Preliminary studies of hydrothermally altered massive basalts formed at the fast-spreading Mendoza Rise and recovered from DSDP Holes 597B and 597C indicate the presence of three secondary mineral assemblages which formed in the following order: (1) trioctahedral chlorite and talc, (2) goethite and smectite, and (3) calcite and celadonite. The sequential precipitation of these mineral assemblages denotes high water:rock ratios and time-varying conditions of temperature (early >200°C to late <30°C) and state of oxidation (early nonoxidative to late oxidative). A decrease in the relative proportion of oxidative mineral assemblages with depth to 70 m in Site 597 basement indicates a zone of oxidative alteration that became shallower with time as the deeper, more constricted fracture systems were filled by secondary mineralization.
In this report we present the first results of the K-Ar dating of celadonite formation age; celadonite formation reflects end-stage hydrothermal alteration in Site 597 basement. Three celadonite dates obtained from Site 597 samples include 13.1 ± 0.3 m.y. from 17 m basement depth (Hole 597B), 19.9 ± 0.4 m.y. from 18 m basement depth (Hole 597C), and 19.3 ± 1.6 m.y. from 60 m basement depth (Hole 597C).
The age of host rock crystallization (28.6 m.y.) and the K-Ar dates of celadonite formation establish that hydrothermal alteration in the upper 70 m of Site 597 basement continued for at least 10 m.y. and possibly as long as 16 m.y. after basalt crystallization at the ridge crest. Assuming a half-spreading rate of 55 km/m.y., we calculate that hydrothermal circulation was active in shallow basement at a distance of at least 550 km off ridge crest and possibly as far as 1000 km off ridge crest.
Project(s):
Deep Sea Drilling Project (DSDP)
Coverage:
Latitude: -18.807200 * Longitude: -129.770300
Date/Time Start: 1983-03-02T00:00:00 * Date/Time End: 1983-03-02T00:00:00
License:
Creative Commons Attribution 3.0 Unported (CC-BY-3.0)
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4 datasets
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Datasets listed in this publication series
- Peterson, C; Duncan, RA; Scheidegger, KF (1986): (Table 4) K-Ar determinations for celadonite and proto-celadonite from DSDP Site 92-597 altered basalts. https://doi.org/10.1594/PANGAEA.792590
- Peterson, C; Duncan, RA; Scheidegger, KF (1986): (Table 1) Observed modes of secondary mineral occurrence and sampling intervals from altered basalts at DSDP Holes 92-597B and 92-597C. https://doi.org/10.1594/PANGAEA.792574
- Peterson, C; Duncan, RA; Scheidegger, KF (1986): (Table 2) Relative abundances of secondary minerals forming amygdule and fracture fillings in altered basalts at DSDP Holes 92-597B and 92-597C. https://doi.org/10.1594/PANGAEA.792587
- Peterson, C; Duncan, RA; Scheidegger, KF (1986): (Table 3) Geochemistry at DSDP Hole 92-597C. https://doi.org/10.1594/PANGAEA.792588