A NanoSIMS Investigation on Timescales Recorded in Volcanic Quartz From the Silicic Chon Aike Province (Patagonia)

Abstract

Textural and chemical differences in coeval rhyolitic effusive and explosive eruptions are commonly observed, and numerical models predict different timescales for the eruption of crystal-rich mushes versus crystal-poor magmas. We compare quartz zonation and diffusion timescales of crystal-rich rhyolitic ignimbrites and crystal-poor rhyolitic lava flows from the Jurassic Chon Aike Province exposed in Patagonia (Argentina). The timescales are assessed by using diffusion modeling based on nanoscale secondary ion mass spectrometry (NanoSIMS) analysis of titanium (Ti) concentration profiles in quartz crystals oriented by image analysis using micro-tomography. Quantitative Ti-data were acquired by SIMS to estimate crystallization temperatures. The textural and geochemical analysis revealed clear differences between crystal-poor rhyolitic lava flows and crystal-rich rhyolitic ignimbrites. Quartz crystals from rhyolitic lava flows display simple oscillatory cathodoluminescence (CL) zoning interpreted to be magmatic and diffusion chronometry suggest a short timescale for quartz crystallization from 5.6 ± 2.2 to 41.6 ± 9.8 years. Resorption textures are rare, and hence crystals in rhyolitic lava flows recorded a simple, rapid extraction, transport and eruption history for these crystal-poor melts. Rhyolitic ignimbrites, in contrast, reveal complex zoning patterns, reflecting several episodes of partial resorption and growth throughout their crystallization history. The complex quartz zoning textures together with longer diffusion times (<350 years), rather suggest a storage in a mush with fluctuating pressure and temperature conditions leading to intermittent resorption. Yet, a final quartz overgrowth rim occurred over a much shorter timescale in the order of years (<3 years). This implies, that crystal-rich mushes can be re-mobilized very fast, as fast as crystal-poor magmas. The use of in-situ methods with a high spatial resolution, like NanoSIMS, is critical to resolve very short magmatic timescales.

Deciphering Clues Regarding Magma Composition Encoded in Quartz‐Hosted Embayments and Melt Inclusions Through Direct Numerical Simulations

“…We apply two types of initial defects, the trapezoidal dip and the round hollow. Defects with similar shapes commonly exist on quartz crystals and may form from skeletal growth at early stages of crystallization (Barbee et al., 2020; Loewen et al., 2017) and crystal dissolution (Busby & Barker, 1966; Chang & Meinert, 2004; Nakamura & Shimakita, 1998; Ruefer et al., 2021; Seitz et al., 2018).…”

“…We initialize our crystal surface with a defect. These defects may form through various mechanism, such as skeletal growth (Barbee et al., 2020; Loewen et al., 2017), crystal dissolution (Busby & Barker, 1966; Chang & Meinert, 2004; Nakamura & Shimakita, 1998; Ruefer et al., 2021; Seitz et al., 2018), and defects in the crystal lattice (Jollands et al., 2022; Potrafke et al., 2019; Stalder, 2021). With the simulated embayments and melt inclusions forming during crystal growth, we then quantify the relationship between the compositions of the entrapped and average melt.…”

Editorial: Volumes, Timescales, and Frequency of Magmatic Processes in the Earth's Lithosphere

“…As elsewhere in this volume, we highlight the additional insight that can be gained by combining approaches, or linking traditional and more novel methods. Seitz et al (2018) use nanoscale secondary ion mass spectrometry, coupled to compared quartz zonation, Ti-inquartz thermometry, and diffusion chronometry to assess eruption timescales for coeval rhyolitic crystal-rich and crystalpoor magmas from the Jurassic Chon Aike Province in Patagonia (Argentina). The data support rapid melt extraction and eruption in < 10 years in the crystal-poor systems.…”

Composition and compositional zoning of olivine as a tracer for pre-eruptive magmatic processes: Application to Piton de la Fournaise, Laacher See, and Shiveluch volcano

“…Common pairs of major / trace elements in abundant minerals have been established for diffusion modeling in volcanic systems: Mg-Fe in olivine Albert et al 2015, Mg-Fe in pyroxene Chamberlain et al 2014;Krimer and Costa 2017), Sr-Ba in plagioclase (Zellmer et al 1999(Zellmer et al , 2003b, K-Na and Sr-Ba in sanidine (Morgan and Blake 2006;Chamberlain et al 2014;Iovine et al 2017;Rout and Wörner 2019), and Ti in quartz (Matthews et al 2012;Chamberlain et al 2014;Seitz et al 2018).…”