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Conference Papers Year : 2015

Magmatic to hydrothermal zircons: Textural and chemical evolution

Abstract

Zircon is undoubtedly the most sought-after mineral for geochemical studies, for its ability to provide information on its host rock, spanning from geochronology, tracing of source and processes, geothermometry, and, recently, redox conditions [1]. However, it is crucial to ascertain its primary origin, and in the past two decades there has been increasing evidence of its crystallization from hydrothermal fluids [2]. Two of the main characteristics that are widely used to ascertain the magmatic or hydrothermal origin of zircon are texture and trace-element chemistry. However, most of these data are contradictory and can be similarly attributed to a primary and secondary origin [3], resulting in a poor understanding of hydrothermal zircon characteristics. We present data on a suite of zircons from the Ambohimirahavavy alkaline complex, Madagascar, that display impressive textural, morphological and compositional variations, strongly suggesting a span in origin from magmatic to hydrothermal (Fig. 1). Clearly magmatic zircons yield ages of 20.40 ± 0.16 and 21.21 ± 0.44 Ma. Hydrothermal zircon yields a similar age of 20.64 ± 0.48 Ma. Evidence for hydrothermal origin includes its occurrence with quartz in pseudomorphs after primary minerals, as botryoidal crystals filling cavities, and precipitation in exoskarn [4]. Strong variations in the amounts and distribution of trace element also occur among different sectors in zoned crystals.

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Geochemistry
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Dates and versions

insu-01207132 , version 1 (30-09-2015)

Identifiers

  • HAL Id : insu-01207132 , version 1

Cite

Guillaume Estrade, Stefano Calvi, Didier Béziat, Marc Poujol. Magmatic to hydrothermal zircons: Textural and chemical evolution. Goldschmidt 2015, Aug 2015, Prague, Czech Republic. pp.abstr. 847. ⟨insu-01207132⟩
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