Geochemical and Textural Features of Apatites from Propylitic to Advanced Argillic Hydrothermal Alteration Zones in the Sharlo Dere Area, Chelopech Cu-Au Deposit, Bulgaria
Open Access
Abstract
Apatite is a widespread accessory mineral, which can provide information on the geochemical characteristics of magma and the conditions of hydrothermal alteration of the rocks in magmatic–hydrothermal deposits. This study aims to understand the relationships between the geochemical and textural features of apatites from diorite porphyries that have undergone different degrees of hydrothermal alteration in the Sharlo Dere area, Chelopech epithermal Cu-Au deposit, Bulgaria. The apatites were characterized by laser ablation–inductively coupled plasma mass spectrometry, scanning electron microscopy with energy-dispersive X-ray spectroscopy, electron probe microanalysis with wave-dispersive spectroscopy, optical cathodoluminescence and multi-element mapping. Magmatic apatites from “hematitic”, propylitic and propylitic-sericitic zones of alteration are distinguished by euhedral crystals with oscillatory zoning and brown luminescence in CL images. In quartz-sericitic alteration zones, apatite has a yellow CL response. Hydrothermally altered apatites in the diorite porphyries overprinted by advanced argillic alteration have corroded, irregular forms and pink-green luminescence. Apatite crystals of magmatic origin reveal high contents of chlorine, strontium, light rare earth elements (LREE), negative Eu anomalies and high LaN/SmN and CeN/YbN ratios. Hydrothermally altered or hydrothermal apatites are distinguished by their higher contents of Na2O, F, SO3, Y and middle rare earth elements (MREEs) and their low LaN/SmN and CeN/YbN ratios. The intensity of hydrothermal alteration affects the luminescence and major and trace element contents, including the rare earth element patterns in the apatites, implying apatite can be used as a geochemical indicator to study magmatic–hydrothermal ore deposits.Keywords
Funding Information
- REXPro project (BG-RRP-2.011-0040-C01/02)
This publication has 44 references indexed in Scilit:
- The redox budget of the Mariana subduction zoneEarth and Planetary Science Letters, 2019
- Halogens, trace element concentrations, and Sr-Nd isotopes in apatite from iron oxide-apatite (IOA) deposits in the Chilean iron belt: Evidence for magmatic and hydrothermal stages of mineralizationGeochimica et Cosmochimica Acta, 2019
- Tectonic, magmatic, and metallogenic evolution of the Late Cretaceous arc in the Carpathian‐Balkan orogenTectonics, 2015
- High-resolution LA-ICP-MS trace element mapping of igneous minerals: In search of magma historiesChemical Geology, 2015
- Subaqueous environment and volcanic evolution of the Late Cretaceous Chelopech Au–Cu epithermal deposit, BulgariaJournal of Volcanology and Geothermal Research, 2014
- Petrology, geochemistry and U–Pb geochronology of magmatic rocks from the high-sulfidation epithermal Au–Cu Chelopech deposit, Srednogorie zone, BulgariaMineralium Deposita, 2007
- Trace element partitioning between apatite and silicate meltsGeochimica et Cosmochimica Acta, 2006
- Late Cretaceous structural control and Alpine overprint of the high-sulfidation Cu–Au epithermal Chelopech deposit, Srednogorie belt, BulgariaMineralium Deposita, 2006
- The composition of the EarthChemical Geology, 1995
- The behavior of apatite during crustal anatexis: Equilibrium and kinetic considerationsGeochimica et Cosmochimica Acta, 1984