MINERALOGY AND GEOCHEMISTRY OF THE TRIADESGALANA PB-ZN-AG-AU INTERMEDIATE-HIGH SULFIDATION EPITHERMAL MINERALIZATION, MILOS ISLAND, GREECE

Η μεταλλοφορία Pb-Zn-Ag-Au Τριάδων-Γαλανών στη ΒΔ Μήλο, αποτελεί μία επιθερμική μεταλλοφορία ρηχού θαλάσσιου περιβάλλοντος που αποτέθηκε κατά μήκος ρηγμάτων ΒΑ διεύθυνσης. Πετρώματα ξενιστές είναι πυροκλαστικά ηλικίας 2.5-1.4 εκ. χρόνων και ανδεσιτικοί/δακιτικοί δόμοι λάβας, με τους οποίους και συνδέεται γενετικά. Η μεταλλοφορία απαντά υπό μορφή λατυποπαγών, φλεβών και πλέγματος φλεβιδίων χαλαζία-βαρίτη-γαληνίτη εντός πετρωμάτων εξαλλοιωμένων σε σερικίτη-αδουλάριου και καολινίτη. Η μεταλλοφορία είναι εμπλουτισμένο σε Mo, W, καθώς και σε βασικά 1970 και πολύτιμα μέταλλα (e.g. Pb, Zn, Ag), όπως και οι γειτονικές μεταλλοφορίες του Κοντάρου-Κατσιμουτίου και Βανίου, υποδεικνύοντας μία κοινή μαγματική πηγή στο βάθος που τροφοδότησε τις μεταλλοφορίες αυτές σε μέταλλα και πτητικά συστατικά. Παραγενετικά δεδομένα υποδεικνύουν αρχική απόθεση σιδηροπυρίτη, και στη συνέχεια φαματινίτη, πολυβασίτη, πυραργυρίτη και Ag-ούχου τετραεδρίτη, και τέλος εναργίτη, παρέχοντας ενδείξεις μεταβαλλόμενων συνθηκών θείωσης κατά τη διάρκειας της μεταλλοφορίας. Η εξέλιξη των ρευστών πλούσιων σε Sb στα αρχικά στάδια πρός As- ούχα ρευστά στα τελευταία στάδια, αποτελεί ένδειξη μιάς νέας μαγματικής συνεισφοράς (πιθανόν υπό μορφή μαγματικών αερίων) στο υδροθερμικό σύστημα. Ο άργυρος απαντά στη δομή των θειοαλάτων (έως 66.2 % κ.β. στον πολυβασίτη, 15.1 % κ.β. στον τετραεδρίτη και 60 % κ.β. στον πυραργυρίτη). Διαδικασίες βρασμού (όπως υποδεικνύει η παρουσία αδουλάριου στη παραγένεση ενδιάμεσης θείωσης), και ανάμειξης με θαλασσινό νερό (παρουσία υπογενετικού χλωριδίου του μολύβδου), σύγχρονες με ανάδυση της περιοχής, έχουν συνεισφέρει στην απόθεση του μεταλλεύματοςThe Triades-Galana Pb-Zn-Ag-Au mineralization is a shallow-submarine epithermal mineralization located along NE-trending faults, NW Milos Island, Greece. It is hosted in 2.5–1.4 Ma pyroclastic rocks and is genetically related to andesitic/dacitic lava domes. Mineralization occurs as breccias, quartz-barite galena veins and stockworks within sericite-adularia or kaolinitic altered rocks. The mineralization is enriched in Mo, W and base- and precious metals (e.g. Pb, Zn, Ag) similarly to the neighbouring mineralization at Kondaros-Katsimouti and Vani, indicating common source of metals from a deep buried granitoid feeding western Milos with metals and volatiles. Paragenetic relations suggest early deposition of pyrite, followed by famatinite, polybasite and Ag-rich tetrahedrite, and then by enargite, suggesting fluctuating sulfidation states during ore formation. The evolution from Sb- towards As-rich enrichment indicate a renewed magmatic pulse (probably in the form of magmatic gases) in the hydrothermal system. Silver is present in the structure of sulfosalts (up to 66.2 wt.% in polybasite-pearceite, 15.1 wt.% in tetrahedrite and 60 wt. % in pyrargyrite). Boiling processes (as evidenced by the presence of adularia accompanying intermediate-sulfidation ore) and mixing with seawater (presence of hypogene lead chlorides) and contemporaneous uplift, contributed to ore formation

Tellurides and bismuth sulfosalts in gold occurrences of Greece: mineralogical and genetic considerations

Pre-Tertiary to Tertiary gold deposits in Greece occur in a wide range of genetic types including volcanic massive sulfides, orogenic, intrusion-hosted, skarn, manto-, porphyry- and epithermal-type ores. Almost all of the gold mineralization hosts various Bi-tellurides and Bi-sulfosalts, which in addition to Au-Ag-tellurides, are indicators of specific physicochemical conditions of ore formation. The Bi-bearing mineralization can be subdivided into three groups regarding their spatial relationship to gold: (a) mineralization which lacks tellurides but includes Bi-sulfosalts and native gold, (b) mineralization where Bi-tellurides of the reduced-type (joseite-A, joseite-B, pilsenite) accompany Bi-sulfosalts, native bismuth and native gold, (c) deposits/prospects where Au-Ag-tellurides are abundant and Bi-tellurides and Bi-sulfosalts are absent. Bi-telluride and -sulfosalt mineralization in Greece underwent several stages of remobilization during successive accretionary episodes in active continental margins and arc terranes during the Carboniferous to Pleistocene

Shallow submarine epithermal Pb-Zn-Cu-Au-Ag-Te mineralization on western Milos Island, Aegean Volcanic Arc, Greece: Mineralogical, geological and geochemical constraints

Milos Island contains several epithermal deposits (e.g., Profitis Ilias-Chondro Vouno Pb-Zn-Ag-Au-Te-Cu, Triades-Galana-Agathia-Kondaros Pb-Zn-Ag-Bi-W-Mo ± Cu-Au, and Katsimoutis-Kondaros-Vani Pb-Zn-Ag-Mn) of Late Pliocene to Early Pleistocene age. These deposits are hosted in calc-alkaline volcanic rocks emplaced as a result of three successive magma pulses in an emergent volcanic edifice: submarine rhyolitic to rhyodacitic cryptodomes at ca. 2.7. Ma (Profitis Ilias-Chondro Vouno), submarine to subaerial andesite to dacite domes at ca. 2.2 to 1.5. Ma (Triades-Galana-Kondaros-Katsimouti-Vani). Hydrothermal alteration of the volcanic rocks includes advanced argillic- (both hypogene and steam-heated), argillic, phyllic, adularia-sericite and propylitic types. In the northern sector (Triades-Galana-Agathia-Kondaros), initial magma degassing derived from andesitic-dacitic intrusives along NE-SW to E-W trending faults resulted in the development of pre-ore hypogene advanced argillic alteration (dickite, alunite, ± diaspore, pyrophyllite, halite, and pyrite) in a submarine environment. Mineralogical data indicate common features among the Profitis Ilias-Chondro Vouno, Kondaros-Katsimoutis-Vani and Triades-Galana mineralized centers, all of which are characterized by the presence of galena, Fe-poor sphalerite, and chalcopyrite as well as abundant barite, adularia, sericite and, to a lesser extent, calcite, which are typical of intermediate-sulfidation epithermal type deposits. Locally, at Triades-Galana and Kondaros-Agathia, high-sulfidation conditions prevailed as suggested by the presence of coexisting enargite and covellite. The high silver and gold content of the western Milos deposits is derived from Ag-bearing sulfosalts (polybasite, pearceite, pyrargyrite, freibergite) and tellurides. Gold at Profitis Ilias, both as native gold and silver-gold tellurides, is present in base-metal precipitates within multicomponent blebs, which recrystallized to form hessite, petzite, altaite, coloradoite, and native gold. Mineralogical evidence (e.g. microchimney structures, copper sulfides, widespread occurrence of barite, aragonite) suggests that precious metal mineralization in western Milos mineralization formed in a submarine setting. We present information on the surface distribution of Au, Ag, Cu, Pb, Zn, As, Sb, Hg, Mo, Bi, W and Cd at western Milos. Gold is enriched at Profitis Ilias-Chondro Vouno deposits and to a lesser extent at Triades-Galana. Arsenic is absent from the southern sector but shows elevated concentrations together with molybdenum, bismuth and tungsten at the northern sector (Triades-Galana, Vani deposits). The differences in precious and base metal abundances may be related to the depths at which the deposits are exposed, and/or different sources of magma. The metal signatures of the Triades-Galana and Agathia-Kondaros-Katsimouti-Vani (Mo-Bi-W-As-Hg-Ag-Au) occurrences compared to Profitis Ilias (Te-Au-Ag) reflect different sources of magma (dacite-rhyodacite for Profitis Ilias, andesite-dacite for Triades-Galana, and dacite for Kondaros-Katsimoutis). The enrichment of Te, Mo, W, and Bi in the deposits is a strong indication of a direct magmatic contribution of these metals. At western Milos, precious and base-metal vein mineralization was deposited during episodic injection of magmatic volatiles and dilution of the hydrothermal fluids by seawater. The mineralization represents seafloor/sub-seafloor precipitation of sulfides that formed in stockwork zones. Base and precious metal mineralization formed from intermediate- to high-sulfidation state fluids and mostly under boiling conditions as indicated by the widespread occurrence of adularia associated with metallic mineralization. We speculate that the widespread occurrence of boiling and the shallow depth of the precious- and base-metal emplacement prevented the formation of seafloor massive sulfides. © 2013

Tellurides and bismuth sulfosalts in gold occurrences of Greece: mineralogical and genetic considerations

Pre-Tertiary to Tertiary gold deposits in Greece occur in a wide range of genetic types including volcanic massive sulfides, orogenic, intrusion-hosted, skarn, manto-, porphyry- and epithermal-type ores. Almost all of the gold mineralization hosts various Bi-tellurides and Bi-sulfosalts, which in addition to Au-Ag-tellurides, are indicators of specific physicochemical conditions of ore formation. The Bi-bearing mineralization can be subdivided into three groups regarding their spatial relationship to gold: (a) mineralization which lacks tellurides but includes Bi-sulfosalts and native gold, (b) mineralization where Bi-tellurides of the reduced-type (joseite-A, joseite-B, pilsenite) accompany Bi-sulfosalts, native bismuth and native gold, (c) deposits/prospects where Au-Ag-tellurides are abundant and Bi-tellurides and Bi-sulfosalts are absent. Bi-telluride and -sulfosalt mineralization in Greece underwent several stages of remobilization during successive accretionary episodes in active continental margins and arc terranes during the Carboniferous to Pleistocene.This proceeding is published as Voudouris, P., Spry, P.G., Melfos, V., and Alfieris, D., 2007, Tellurides and bismuth sulfosalts in gold occurrences of Greece: mineralogy and genetic considerations, in Kojonen, K. K., Cook, N.J., and V.J. Ojala (eds.), Au-Ag-Te-Se deposits, Proceedings of the 2007 Field Workshop (Espoo, Finland, August 26-31, 2007). Geological Survey of Finland Guidebook 53, p. 85-94.</p

New geochemical and mineralogical constraints on the genesis of the Vani hydrothermal manganese deposit at NW Milos island, Greece: Comparison with the Aspro Gialoudi deposit and implications for the formation of the Milos manganese mineralization

The Mn-Ba-Pb deposit at Aspro Gialoudi in NW Milos is shown to be a fossil inhalative-exhalative hydrothermal deposit that represents the deepest part of the Vani succession at the western extremity of the main Vani manganese deposit. The geology of the Vani-Aspro Gialoudi area is characterized by Upper Pliocene-Lower Pleistocene dacitic and rhyodacitic lava domes, which are overlain by the Vani volcaniclastic unit considered to be part of the 2.66–1.44 Ma magmatic event at Milos Island. The presence of in-situ and intrusive hyaloclastite breccias surrounding the coherent lava domes at Aspro Gialoudi and Vani areas indicates submarine emplacement for the domes. The dacitic-rhyodacitic domes are variously altered (mainly propylitic and/or argillic alteration, silicified and in some cases locally exhibiting adularia alteration). Both Aspro Gialoudi and main Vani deposit are located proximal to fault systems: the main Vani manganese deposit is adjacent to the NW-trending Kondaros-Katsimouti-Vani Dome fault, whereas the Aspro Gialoudi deposit is adjacent to the relatively minor NE-trending fault on the west coast of Milos. At Aspro Gialoudi, mineralization took place in a subseafloor and/or seafloor environment and is characterized by a stratabound Mn-barite-rich deposit mainly within a package of propylitized intrusive hyaloclastites and within the overlying sandstones. Banded epithermal veins trending NE-SW and composed of chalcedonic silica/quartz + barite + Mn-oxide ± sulfides crosscut the dacitic lavas, the hyaloclastites and the overlying volcaniclastic sequence at Aspro Gialoudi and are considered to represent the feeder zones of the manganese-barite mineralization. Within the veins, early sulfide (galena-sphalerite) barite and quartz deposition is followed by manganese oxides and aragonite, thus resembling the epithermal-style Pb-Zn-Ag-Mn mineralization across the NW-trending Katsimoutis-Kondaros-Vani fault. Mineralization in Aspro Gialoudi and Vani deposits seems to be controlled by alternating cycles of deposition of sulfides and hydrothermal manganese oxides within the faults. Manganese deposition in both deposits formed in a similar manner, namely by transport of hydrothermal fluids through the adjacent fault systems into a reservoir of volcanoclastic sandstone and hyaloclastites to produce a deposit initially consisting of principally of pyrolusite and occasionally ramsdellite, which were subsequently replaced by cryptomelane, hollandite, coronadite and hydrohaeterolite. Precipitation of hydrothermal manganese oxides took place very quick and under microbial Mn(II) oxidation. Compositional data show that metallic elements most enriched in the Aspro Gialoudi and Vani manganese deposits relative to the average continental crust, lie in the sequences Pb &gt; Cd &gt; Mn &gt; As &gt; Sb &gt; Zn &gt; W &gt; Tl &gt; Ba &gt; Cu &gt; Mo &gt; Co &gt; Bi and As &gt; Sb &gt; Pb &gt; Mn &gt; Tl &gt; Cd &gt; Zn &gt; W &gt; Cu &gt; Ba &gt; Mo &gt; Co, respectively. Mineralogical and geochemical (e.g. REE) data from both Aspro Gialoudi and main Vani deposit are taken to indicate mainly a seawater source for the hydrothermal fluids. These two deposits are genetically and spatially related to base- and precious metal intermediate-sulfidation epithermal mineralization. They formed successively by similar processes and are considered to be integral parts of the same hydrothermal system. © 2016 Elsevier B.V

A new porphyry Mo mineralization at Aisymi-Leptokarya, south-eastern Rhodope, north-east Greece: Geological and mineralogical constraints

A new porphyry Mo prospect has been discovered in the Aisymi-Leptokarya area, along the southern margin of the Byala Reka–Kechros metamorphic dome, south-eastern (SE) Rhodope metallogenic zone. The study area is dominated by an Oligocene felsic dike complex, which hosts the porphyry Mo mineralization and intrudes into upper Eocene sandstones-marls and the Leptokarya monzodiorite pluton. The Aisymi-Leptokarya felsic dike complex displays a rhyodacitic to dacitic composition with post-collisional affinities. The porphyry Mo mineralization occurs in the form of porphyry-style quartz stockworks in the felsic dike complex associated with potassic alteration characterized by hydrothermal K-feldspar. The ore minerals consist mainly of pyrite, molybdenite, kesterite, bismuthinite and galena within both the stockwork and the rock matrix. Bulk ore analyses indicate enrichment in Mo (up to 215 ppm), Se (up to 29 ppm), Bi (up to 8 ppm) and Sn (up to 14 ppm) in the porphyry quartz veins. Late-stage, north-east (NE-) and north-west (NW-)trending milky quartz intermediate-sulfidation epithermal veins with base metals, crosscut previous vein generations and are characterized by Ag, Sn and Te anomalies. The Aisymi-Leptokarya porphyry Mo prospect is set in a back-arc geotectonic regime and shares similarities to other post-subduction porphyry molybdenum deposits elsewhere. © 2018 by the authors. Licensee MDPI, Basel, Switzerland

Enoxaparin Reduces Catheter-associated Venous Thrombosis After Infant Cardiac Surgery

Background Central venous catheter (CVC) related venous thrombosis (VT) after pediatric cardiac surgery increases morbidity and mortality. Although VT prevention using low-dose anticoagulation therapy has proven ineffective, anticoagulation therapy using high-dose enoxaparin to achieve a therapeutic anti-Xa level has not been studied. We hypothesized that high-dose enoxaparin would reduce VT after pediatric cardiac surgery. Methods Enoxaparin was administered to infants aged less than 150 days when postoperative CVC duration was anticipated to extend beyond 5 days. The primary outcome was the rate of VT, reexploration for bleeding, and postoperative red blood cell transfusions per 1000 CVC days. Results From 2012 to 2019, 157 infants were treated with enoxaparin. Infants were divided into two groups: (1) subtherapeutic (n = 51), in which therapeutic anti-Xa level (0.5 to 1.0 IU/mL) was not achieved; and (2) therapeutic (n = 106), in which therapeutic anti-Xa level was achieved. Baseline demographics demonstrated a lower age at operation in the therapeutic group. The subtherapeutic group had a higher VT rate per 1000 CVC days (8.2) compared with the therapeutic group (2.6; P = .005). Reexploration for bleeding was similar between groups. The number of postoperative red blood cell transfusions per 1000 CVC days was significantly greater in the subtherapeutic group (109.4 vs 81.6; P = .008). Multivariate analysis demonstrated that higher median anti-Xa levels reduced the risk of VT (odds ratio 0.02; 95% confidence interval, 0.001 to 0.63; P = .02). Conclusions These data suggest that enoxaparin treatment resulting in a therapeutic anti-Xa level reduces postoperative CVC-associated VT without increasing bleeding complications