Experimental study on the production of rhyolites from basaltic sources in the bimodal Snake River Plain-Yellowstone province
Mineralogy, Petrology and Geochemistry
Final Report Abstract
The ICDP drilling in the Snake River Plain volcanic province (western United States) was aimed to trace the Snake River Plain – Yellowstone (SRPY) hotspot and its interaction with the continental lithosphere. Over the last 15 Million years, the SRPY-hotspot migrated ca. 600 km eastwards resulting in a bimodal rhyolitic-basaltic magmatism. The project was focusing on the evolution of storage conditions of basaltic magma reservoirs with time. Based on the investigation of the ICDP Kimama drill core, a time span covering approximately 6 million years with 78 lava flows could be covered. A detailed mineralogical and geochemical investigation of selected samples as well as experiments were performed to determine magma storage conditions. The experimental approach was primarily designed to simulate crystal fractionation from basaltic sources and to check if extreme fractionation can lead to the formation of rhyolitic liquids such as those found in SRPY. Crystallization experiments were performed at 300 and 600 MPa in the temperature range 1000 -1100 °C. The results indicate that rhyolites of the SRPY province can be produced by fractional crystallization in a single-liquid stability field and in a narrow temperature range of less than 50 °C. However, silicate liquid immiscibility could be observed in some experiments and may play a role in the differentiation process. Time scales of magmatic processes were investigated based on chemical zoning of olivine crystals and on the modelling of Fe-Mg interdiffusion. Two populations of olivine were identified: (1) Olivine that were not in equilibrium with the melts are interpreted to be entrained by replenishing magma, escaping from the mid-crustal mafic sills. They were stored at shallow reservoirs for ca. 11-276 days prior to eruption. (2) Shorter timescales of ca. 5-57 days are obtained for olivine phenocrysts that are in near-equilibrium with the melt. These shorter timescales are interpreted to record the transport time during magma ascent from the shallow reservoir to lava emplacement at surface under magmatic temperature. The combination of thermobarometric observations, of textural observations of olivine crystals and of constraints from timescales indicate a multiple-stage basaltic magma plumbing system spanning a wide range of crustal depths below the central SRP.
Publications
-
Experimental study on the production of rhyolites from basaltic sources in the bimodal Snake River Plain-Yellowstone province. IODP/ICDP Kolloquium 2015, Bonn, Germany
Almeev R; Charlier B; Namur O; Holtz F; Wang M & Shervais J
-
Experimental study on the production of Snake River Plain-Yellowstone rhyolites. EMPG XV, ETH Zurich, Switzerland
Wang M; Namur O; Almeev R; Charlier B & Holtz F
-
Petrogenesis of basalt in Kimama core and experimental study on rhyolite of bimodal Snake River Plain. IODP/ICDP-Berichtskolloquium, Heidelberg, Germany
Wang M; Namur O; Almeev R; Charlier B & Holtz F
-
Petrogenesis of Snake River Plain basalts from the Kimama core and experimental study on ferrobasalts IODP/ICDP-Berichtskolloquium, Braunschweig, Germany
Wang M; Namur O; Almeev R; Charlier B; Neave DA & Holtz F
-
Petrogenesis of Snake River Plain basalts from the Kimama core: an experimental study on ferrobasalts. IODP/ICDP Kolloquium 2018, Potsdam, Germany
Wang M; Namur O; Almeev R; Charlier B & Holtz F
-
Study of genesis on bimodal volcanic rocks, Snake River Plain- Yellowstone province, USA (in Chinese). The 9th Chinese Symposium on volcanology, Changbaishan, China
Wang M; Almeev R; Hou T & Holtz F
-
Petrogenesis study of basalt in the bimodal Snake River Plain -Yellowstone province (in Chinese). Annual Meeting of Chinese Geosciences Union (CGU), Chongqing, China
Wang M; Almeev R; Hou T & Holtz F
