(1) (2) (3) (4) (5) National and Kapodistrian University of Athens est. 1837

First zunyite-bearing lithocap in Greece: The case of Konos Hill Mo-Re-Cu-Au porphyry system

Constantinos Mavrogonatos¹, Panagiotis Voudouris¹, Paul G. Spry², Vasilios Melfos³, Stephan Klemme⁴, Jasper Berndt⁴, Robert Mori⁵ and Christos Kanellopoulos¹.

a b 1. Introduction and Regional Geology Advanced argillic alteration Zunyite [AlSiO(OH,F)Cl] is a rare F- and Cl- Qz stockwork bearing, aluminosilicate that was originally described from and named after the Zuni Mine, Colorado, USA. Zunyite has been recognized as a rare mineral in Phyllic alteration c advanced argillic alteration assemblages, which commonly develop in shallow levels, above porphyry Cu-Au deposits. In the Sapes-Kassiteres district, lithologies of the Makri d e Qz f unit (Circum Rhodope Belt) predominate, especially in Qz veins its southern part. Overlying extended outcrops of the

Eocene volcanosedimentary sequence occupy most of Alu+Qz Qz+Alu+Zn the study area, along with hydrothermally-altered subvolcanic intrusions. Konos Hill, its most prominent topographic feature, Figure 2. Field and hand-specimens photographs: (a) Panoramic view of Konos consists of a hydrothermally-altered granodiorite which Hill; (b) Quartz-alunite-zunyite bearing rocks on top of Konos Hill; (c) Quartz- alunite-diaspore bearing in the NW slopes of Konos Hill; (d,e) Hand-specimens intruded into the volcanosedimentary sequence (Figure of quartz-alunite and quartz-alunite-zunyite assemblages; (f) Quartz porphyry 1). Further to the E-NE part of the study area, a stockwork veins in sericitic-altered granodiorite (Saporema Creek). m o n z o d i o r i t i c b o d y h a s i n t r u d e d t h e Figure 1. Geological and alteration map of volcanosedimentary sequence and the granodiorite. 3. Methods Konos Hill area. Black square in the map of Previous studies in this area have shown that Greece (top-left corner), marks the Advanced argillic alteration minerals were location of the study area. granodiorite hosts the Konos Hill porphyry Cu-Mo-Re- identified through XRD analyses, at the Faculty of Au porphyry prospect. Geology, University of Athens. 2. Alteration and Mineralization Chemical compositions were determined by EPMA Advanced argillic alteration at Konos Hill is related to E-W, NNW-SSE and (JEOL 8530F instrument) at the Institute for N-S trending faults and produced a significant overprint of the porphyry-style Mineralogy, University of Munster, Germany. alteration and mineralization, which is exposed in lower topographic areas a b c Qz (Figure 2a). Alu Silicified zones grade outwards into advanced argillic assemblages Alu+Qz ( F i g u r e s 2 b - e ) . A d j a c e n t t o s i l i c i fi c a t i o n , a l u n i t e + A P S Zn minerals+quartz+zunyite±pyrophyllite assemblages predominate, while Zn Alu+Qz Qz more distal assemblages are composed of quartz+alunite+APS Zn minerals+diaspore+kaolinite±pyrophyllite). d e f Advanced argillic alteration assemblages evolve through a transitional Qz zone of quartz+alunite+pyrophyllite+sericite, into a typical sericite-rich assemblage, which is the most widespread type of hydrothermal alteration. Qz Porphyry-style quartz stockwork veins (Figure 2f), hosted in granodiorite, Alu APS Dsp comprise chalcopyrite-pyrite-molybdenite-rheniite. Alu Alu+Qz a b Figure 3. Transmitted light microphotographs of advanced argillic alteration assemblages from the Alu+Qz 3. Mineral Chemistry Konos Hill area. (a,b) Euhedral zunyite (Zn) crystals in association with quartz and tabular alunite (Alu+Qz, // and + nicols respectively); (c) Alunite (Alu) vein crosscutting silicified granodiorite (+ Zn Ÿ Ηem Zunyite: SiO and AlO range nicols); (d) Tabular alunite crystals in association with quartz (Qz, + nicols); (e) APS minerals are from 22.7 to 25.14 wt.%, and found in the core of pseudocubic alunite (+ nicols); (f) Subhedral diaspore (Dsp) crystals set in an alunite and quartz (Alu+Qz) dominated matrix (+ nicols). Zn Alu+Qz Ηem 54.97-55.81 wt.%. F and Cl 100µm 50µm range from 4.07-5.93 and 4. Conclusions c d 2.72-2.97 wt.%. Traces of Ÿ Advanced argillic alteration in Konos Hill was formed by acidic Alu BaO, TiO, NaO and CeO fluids that were chanelled through fault planes. were detected. Ÿ The presence of zunyite in a lithocap that overlies a porphyry Dsp Ÿ Alunite-Natroalunite: Most deposit, is described here for the first time in Greece and APS alunites are K-rich, (KO up to suggests the availability of F and Cl in the hydrothermal fluid. Alu+Qz 10µm 200µm 9 wt.%). Natroalunite is also Ÿ A T range of 280-350 ˚C for zunyite formation is based on the Figure 4. Back-scattered electron microphotographs: (a,b) common and usually forms similarity of zunyite-bearing assemblages at Konos Hill with Euhedral zunyite (Zn) crystals in association with quartz, tabular euhedral, tabular-shaped alunite (Alu+Qz) and hematite (Hem); (c) APS minerals in the those observed in the Hugo Dummet porphyry Cu-Au deposit core of alunite crystals; (d) Diaspore (Dsp) crystals set in an crystals. NaO content is up to which formed at this range of temperatures. alunite and quartz (Alu+Qz) dominated matrix. 5.12 wt.%, Ÿ APS: analyzed compositions 2.0 1.2 5. References a b Ÿ Voudouris, P. Hydrothermal corundum, topaz, diaspore and alunite supergroup yielded woodhouseite and 1.5 A²⁺+PO₄³⁻=A⁺+SO₄²⁻ 0.9 D²⁺=D⁺ minerals in the advanced argillic alteration lithocap of the Kassiteres-Sapes porphyry-epithermal system, western Thrace, Greece. N. Jahr. Min., 2014, Alunite strontian woodhouseite. 1.0 191/2, 117-136. group 0.6 Ÿ Diaspore: stoichiometric Alunite/Natroalunite Ÿ Khashgerel, B.; Kavalieris, I.; Ken-Ichiro, H. Mineralogy, textures and whole-rock 0.5 Beudantite 0.3 geochemistry of advanced argillic alteration: Hugo Dumett porphyry Cu-Au compositions with traces of Ca+Sr+Ba+Ce+La

group Ca+Sr+Ba+Ce+La deposit, Oyu Tolgoi mineal district, Mongolia. Econ. Geol., 2008, 71(5), 849-863, lumbogummite P 0 doi:10.2113/gsecongeo.71.5.849. TiO, BaO, CeO and NdO. 0 group 0 0.5 1.0 1.5 2.0 0 0.2 0.4 0.6 0.8 1.0 1.2 Ÿ Hedenquist, J.W.; Arribas, A.; Reynolds, T.J. Evolution of an intrusion-centered Ÿ Kaolinite/Pyrophyllite: were P K+Na hydrothermal system: Far Southeast-Lepanto porphyry and epithermal Cu-Au Figure 5. Chemical variation diagrams of analyzed alunite and APS minerals from Konos Hill deposis, Philippines. Econ. Geol., 1998, 93, 373-404. v e r i fi e d t h r o u g h X R D area: (a) Ca+Sr+Ba+Ce+La vs P plot (marked line represents the occupancy of divalent and corresponding author: analyses. trivalent cations in A site, relative to trivalent anions in X site); (b) Ca+Sr+Ba+Ce+La vs K+Na [email protected] plot (marked line represents occupancy of monovalent relative to divalent cations in D site).