AI Summary & Key Takeaways
AI InsightOur results show that typology differences exist between zirconpopulations from both Miocene ignimbrites and Quaternary rhyolitic domes/lavas of the CAVP.
📌 3 Key Takeaways
Abstract
Zircon typology was developed nearly half a century ago as a tool for constraining the thermochemical conditions in graniticmagmas from the morphology of zircon prismatic and pyramidal crystal surfaces. Although the method precedes experimentallyconstrained zircon-based thermometers (zircon saturation, Ti-in-zircon), the morphology of zircon remains an important criterionfor zircon studies commonly relying on visual recognition of crystals during sample purification via hand-picking. This may introduceselection bias if morphologically distinct zircon crystals are present in a population. We conducted a comparison between zircontypology and thermochemical constraints from zircon thermometry and whole rock compositions. Therefore, we focused on zirconpopulations from diverse volcanic rocks from the Central Anatolian Volcanic Province (CAVP), which erupted during the UpperMiocene to Quaternary in a continental environment in a postcollisional extensional regime. Neogene rhyolitic volcanism producedwidespread pyroclastic rocks (ignimbrites, and subordinate fall-out deposits), which are interstratified with fluviolacustrine sedimentsand local lava flows originating from various volcanic centers in the region. Zircon crystals from Neogene ignimbrites are mostlyintermediate-temperature, calc-alkaline hybrid type, whereas zircons from Quaternary rhyolitic domes/lavas fall into typology trendsassigned to subalkaline mantle-type granites with low temperatures and high alkalinity indices. Trends in zircon saturation andzircon crystallization temperatures in CAVP ignimbrites are broadly consistent with typology temperature estimates, but temperaturedifferences between these estimates are slightly higher or lower. However, these deviations may partly result from zircon typologyrelying on crystal shape, and thus the latest crystallization event, which could result in bias between the granitic rocks used for theoriginal typology development and the volcanic rocks investigated here. Our results show that typology differences exist between zirconpopulations from both Miocene ignimbrites and Quaternary rhyolitic domes/lavas of the CAVP. These differences affect the temperaturevalues obtained from zircon typologies that also correlate with conventional quantitative thermometric calculations.