2025/05/01 by Georg F. Zellmer, Yoshiyuki Iizuka · 1 voice
Earth and Planetary Sciences · Materials Science · #Geological and Geochemical Analysis #Crystallization and Solubility Studies
paper · pdf · doi:10.3749/2400041
openalex publication_date 2025/05/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/31
Abstract Fracturing of crystals in volcanic rocks is a phenomenon that has been widely recognized. However, the history of repeated crystal fragmentation as recorded by the phenocrysts carried in volcanic rocks has yet to be considered. We provide examples from hot spot, arc, back-arc, and ocean ridge settings indicating that crystals often display linear fractures, some following cleavage planes, and show that elemental mapping is necessary to identify cryptic fractures by providing insights into cryptic zoning and evidence for fracture annealing. Crystal fragmentation appears to be a fundamental and recurrent process operating in magmatic systems, irrespective of tectonomagmatic setting or eruption style, and controls both internal crystal zoning patterns and final crystal habit in erupted rock samples. Euhedral crystal habits may frequently result from edge fracturing along cleavage planes, rather than unhindered crystal growth within a melt phase. Recent edge fractures, in fact, provide evidence that the time between crystal fragmentation and eruption is too short to allow the kinetic process of crystallization to operate, supporting contemporary models of dominantly subsolidus transcrustal plutonic systems. Crystal fracturing may impact the application of chronological methods, including geospeedometric and crystal size distribution studies directed at volcanic hazard mitigation. The use of advanced chemical imaging techniques to decipher pre-eruptive processes such as crystal fragmentation becomes paramount.