Unknown
PANGAEA
In:
Supplement to: Gillis, Kathryn M; Ludden, John N; Plank, Terry; Hoy, Lawrence D (1992): Low-temperature alteration and subsequent reheating of shallow oceanic crust at Hole 765D, Argo Abyssal Plain. In: Gradstein, FM; Ludden, JN; et al. (eds.), Proceedings of the Ocean Drilling Program, Scientific Results, College Station, TX (Ocean Drilling Program), 123, 191-199, https://doi.org/10.2973/odp.proc.sr.123.157.1992
Publication Date:
2024-01-09
Description:
Volcanic basement recovered at Hole 765D is characterized by nonpervasive, oxidative alteration, typical of seafloor weathering. Chilled margins and the mesostasis of the lavas are variably altered to assemblages of celadonite, Fe-oxyhydroxides, zeolites, and calcite with trace saponite. Plagioclase is partially altered to Ca-Na zeolites and/or albite. Well-developed alteration halos parallel fracture surfaces and extend several centimeters into the surrounding rock. These clay-rich halos are enriched in K2O and Fe2O3 relative to the adjacent clay-poor rock. The halos and adjacent rock are characterized by d18O values 2 per mil-3 per mil higher than those of fresh MORB. The "freshness" of the samples and the scarcity of saponite suggest that the duration of seawater circulation was short-lived. Albitization of plagioclase indicates that the volcanic rocks were altered initially at low temperatures and were subsequently reheated off-axis in a closed environment. Reheating did not result in significant modification of the bulk composition of the crust.
Keywords:
123-765D; DRILL; Drilling/drill rig; Joides Resolution; Leg123; Ocean Drilling Program; ODP; South Indian Ridge, South Indian Ocean
Type:
Dataset
Format:
application/zip, 5 datasets
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