Marescotti, Pietro; Vanko, David A; Cabella, Roberto (2000): Geochemical composition and atomic formulas of saponites, celadonites and carbonates from ODP Leg 168 sites [dataset publication series]. PANGAEA, https://doi.org/10.1594/PANGAEA.788887, Supplement to: Marescotti, P et al. (2000): From oxidizing to reducing alteration: mineralogical variations in pillow basalts from the east flank, Juan de Fuca Ridge 2000. In: Fisher, A; Davis, EE; Escutia, C (eds.) Proceedings of the Ocean Drilling Program, Scientific Results, College Station, TX (Ocean Drilling Program), 168, 1-18, https://doi.org/10.2973/odp.proc.sr.168.006.2000
Always quote citation above when using data! You can download the citation in several formats below.
Abstract:
With this study, we investigate the mineralogical variations associated with the low-temperature (<100°C) alteration of normal tholeiitic pillow basalts varying in age from 0.8 to 3.5 Ma. Their alteration intensity varies systematically and is related to several factors, including (1) the aging of the igneous crust, (2) the increase of temperatures from the younger to the older sites, measured at the sediment/basement interface, (3) the local and regional variations in lithology and primary porosity, and (4) the degree of pillow fracturing. Fractures represent the most important pathways that allow significant penetration of fluids into the rock and are virtually the only factor controlling the alteration of the glassy rim and the early stages of pillow alteration. Three different alteration stages have been recognized: alteration of glassy margin, oxidizing alteration through fluid circulation in fracture systems, and reducing alteration through diffusion.
All the observed mineralogical and chemical variations occurring during the early stages of alteration are interpreted as the result of the rock interaction with "normal," alkaline, and oxidizing seawater, along preferential pathways represented by the concentric and radial crack systems. The chemical composition of the fluid progressively evolves while moving into the basalt, leading to a reducing alteration stage, which is initially responsible for the precipitation of Fe-rich saponite and minor sulfides and subsequently for the widespread formation of carbonates. At the same time, the system evolved from being "water dominated" to being "rock dominated." No alteration effects in pillow basalts were observed that must have occurred at temperatures higher than those measured during Leg 168 at the basement/sediment interface (e.g., between 15° and 64°C).
Project(s):
Ocean Drilling Program (ODP)
Coverage:
Median Latitude: 47.821866 * Median Longitude: -128.202961 * South-bound Latitude: 47.756500 * West-bound Longitude: -128.752000 * North-bound Latitude: 47.904600 * East-bound Longitude: -127.731000
Date/Time Start: 1996-06-25T09:15:00 * Date/Time End: 1996-08-11T11:57:00
License:
Creative Commons Attribution 3.0 Unported (CC-BY-3.0)
Size:
3 datasets
Download Data
Datasets listed in this publication series
- Marescotti, P; Vanko, DA; Cabella, R (2012): (Table T5) Major compositon and atomic formulas of carbonates from ODP Leg 168 sites. https://doi.org/10.1594/PANGAEA.788886
- Marescotti, P; Vanko, DA; Cabella, R (2000): (Table T4) Major element oxides and atomic formulas of celadonite and celadonite-bearing mixtures from ODP Leg 168 sites. https://doi.org/10.1594/PANGAEA.788885
- Marescotti, P; Vanko, DA; Cabella, R (2000): (Table T3) Major element oxides and atomic formulas of Mg-rich and Fe-rich saponites from ODP Leg 168 sites. https://doi.org/10.1594/PANGAEA.788884