(Table 1) Stable-isotopes of mineral separates and whole-rock powders from altered volcanic rocks of DSDP Hole 62-465A

DOI

Hess Rise, in the western Pacific Ocean, formed in the mid-Cretaceous south of the equator and moved north with the Pacific Plate (Lancelot and Larson, 1975; Lancelot, 1978; Valuer et al., 1979). Southern Hess Rise was a volcanic archipelago, at least until late Albian time, after which it subsided to become one of the major aseismic rises in the present western Pacific. A second pulse of volcanic activity apparently occurred in the Campanian-Maastrichtian interval, which may be related to tectonic uplift of Hess Rise (Valuer and Jefferson, this volume). Trachytic rocks underlie 412 meters of carbonate sediments at Site 465 on southern Hess Rise. Twenty-four meters of trachyte were recovered from a 64-meter cored interval. The rocks are relatively homogeneous in texture, color, and composition, indicating that the cored sequence was probably part of only one magmatic event (Seifert et al., this volume). Large (> 5-mm) vesicles and oxidized parts of some flows suggest subaerial or shallow-water extrusions. The rocks are high in silica and relatively rich in Na2O, K2O, and light rare-earth elements. The upper part of the volcanic-rock sequence is a breccia, the fragments cemented by calcite, pyrite, and rare barite. Some of the resultant veins are more than 1 cm thick. In addition to the veins, many vesicles are also filled with these minerals. Brecciation and the number and thickness of veins decrease with depth in the hole. The degree of weathering, as indicated by water content, also decreases with depth.

Sediment depth is given in mbsf. Empty cells = no data.

Supplement to: O'Neil, James R; Vallier, Tracy L (1981): Stable-isotope compositions and the origin of secondary minerals in altered volcanic rocks from southern Hess Rise, Deep Sea Drilling Project Site 465. In: Thiede, J; Vallier, TL; et al. (eds.), Initial Reports of the Deep Sea Drilling Project (U.S. Govt. Printing Office), 62, 971-974

Identifier
DOI https://doi.org/10.1594/PANGAEA.819819
Related Identifier https://doi.org/10.2973/dsdp.proc.62.153.1981
Metadata Access https://ws.pangaea.de/oai/provider?verb=GetRecord&metadataPrefix=datacite4&identifier=oai:pangaea.de:doi:10.1594/PANGAEA.819819
Provenance
Creator O'Neil, James R; Vallier, Tracy L
Publisher PANGAEA
Publication Year 1981
Rights Creative Commons Attribution 3.0 Unported; https://creativecommons.org/licenses/by/3.0/
OpenAccess true
Representation
Language English
Resource Type Supplementary Dataset; Dataset
Format text/tab-separated-values
Size 74 data points
Discipline Earth System Research
Spatial Coverage (178.919 LON, 33.821 LAT); North Pacific/CONT RISE