Chemical characteristics of ash layers from ODP Leg 104 ...

• Main Authors: Desprairies, Alain, Maury, R C, Joron, Jean Louis, Bohn, Marcel, Tremblay, P
• Format: Article in Journal/Newspaper
• Language: English
• Published: PANGAEA 1989
• Subjects: Drilling/drill rig; Composite Core; Leg81; Leg104; Glomar Challenger; Joides Resolution; Deep Sea Drilling Project DSDP; Ocean Drilling Program ODP; North Atlantic
• Online Access: https://dx.doi.org/10.1594/pangaea.737126; https://doi.pangaea.de/10.1594/PANGAEA.737126

Forty-five volcanic ash horizons cored at Sites 642, 643, and 644 on the Vøring Plateau and ranging in age from early Miocene to Pleistocene, are discussed in terms of their magmatic features as well as their diagenetic evolution. Most of these layers, some centimeters thick, are mainly made of fresh rhyolitic glass. Twenty-five percent of the ash layers, however, contain variable amounts of more basic glass shards, ranging in composition from Mg-rich tholeiites to icelandites through Mg-poor basalts, ferrobasalts, and tholeiitic andesites, and are commonly associated with rhyolitic shards.Many chemically heterogeneous ash layers show bimodal acidic (rhyolites to icelandites) - basic (Mg-rich basalts to ferrobasalts) frequency distributions of the glass shards; intermediate compositions are not simple mixtures between acidic and basic endmembers. We suggest these ash layers result from the ejection of the upper (rhyolitic) to intermediate (ferrobasaltic) levels of density-stratified magma chambers intruded ... : Supplement to: Desprairies, Alain; Maury, R C; Joron, Jean Louis; Bohn, Marcel; Tremblay, P (1989): Distribution, chemical characteristics, and origin of ash layers from ODP Leg 104, Vøring Plateau, North Atlantic. In: Eldholm, O; Thiede, J; Taylor, E; et al. (eds.), Proceedings of the Ocean Drilling Program, Scientific Results, College Station, TX (Ocean Drilling Program), 104, 337-356 ...