HR: 16:00h
AN: V34B-01    [Abstracts]
TI: Drilling of Submarine Shallow-water Hydrothermal Systems in Volcanic Arcs of the Tyrrhenian Sea, Italy
AU: * Petersen, S
EM: spetersen@ifm-geomar.de
AF: IFM-GEOMAR, Wischhofstr. 1-3, Kiel, 24148, Germany
AU: Augustin, N
EM: naugustin@ifm-geomar.de
AF: IFM-GEOMAR, Wischhofstr. 1-3, Kiel, 24148, Germany
AU: de Benedetti, A
EM: arnaldo.debendetti@tiscali.it
AF: Universit degli Studi Roma Tre, L.go San Leonardo Murialdo 1, Roma, 00146, Italy
AU: Esposito, A
EM: esposito@ingv.it
AF: INGV Sezioni di Roma, Via di Vigna Murata 605, Roma, 00143, Italy
AU: Gaertner, A
EM: agaertner@ifm-geomar.de
AF: IFM-GEOMAR, Wischhofstr. 1-3, Kiel, 24148, Germany
AU: Gemmell, B
EM: Bruce.Gemmell@utas.edu.au
AF: CODES Centre for Ore Deposits, University of Tasmania Private Bag 79, Hobart, TAS 7001, Australia
AU: Gibson, H
EM: hgibson@laurentian.ca
AF: Laurentian University, 935 Ramsey Lake Road, Sudbury, P3E 2C6, Canada
AU: He, G
EM: gwhe@21cn.com
AF: COMRA, China Ocean Mineral Resources Association Fuxingmenwai Ave 1, Beijing, 100860, China
AU: Huegler, M
EM: mhuegler@ifm-geomar.de
AF: IFM-GEOMAR, Wischhofstr. 1-3, Kiel, 24148, Germany
AU: Kleeberg, R
EM: kleeberg@mineral.tu-freiberg.de
AF: TU Bergakademie Freiberg, Akademiestr. 6, Freiberg, 09599, Germany
AU: Kuever, J
EM: kuever@mpa-bremen.de
AF: Materialpruefungsanstalt Bremen, Paul-Feller-Str. 1, Bremen, 28199, Germany
AU: Kummer, N A
EM: Nicolai-Alexeji.Kummer@geo.tu-freiberg.de
AF: TU Bergakademie Freiberg, Akademiestr. 6, Freiberg, 09599, Germany
AU: Lackschewitz, K
EM: klackschewitz@ifm-geomar.de
AF: IFM-GEOMAR, Wischhofstr. 1-3, Kiel, 24148, Germany
AU: Lappe, F
EM: flappe@ifm-geomar.de
AF: IFM-GEOMAR, Wischhofstr. 1-3, Kiel, 24148, Germany
AU: Monecke, T
EM: tmonecke@uottawa.ca
AF: Ottawa University, Department of Earth Sciences 140 Louis-Pasteur, Ottawa, K1N 6N5, Canada
AU: Perrin, K
EM: info@neptune.minerals.com
AF: Neptune Minerals, 56 Alfred Street, Misons Point, NSW 2061, Australia
AU: Peters, M
EM: marcp@uni-muenster.de
AF: University Muenster, Geologisch-Paleaontologisches Institut Corrensstr. 24, Muenster, 48149, Germany
AU: Sharpe, R
EM: robina_sharpe@bigpond.com
AU: Simpson, K
EM: Kirstie.Simpson@utas.edu.au
AF: CODES Centre for Ore Deposits, University of Tasmania Private Bag 79, Hobart, TAS 7001, Australia
AU: Smith, D
EM: djsm@bgs.ac.uk
AF: British Geological Survey, 2A Niven's Knowe Raod, Loanhead, EH20 9AU, United Kingdom
AU: Wan, B
EM: hoocloud@yahoo.com.cn
AF: COMRA, China Ocean Mineral Resources Association Fuxingmenwai Ave 1, Beijing, 100860, China
AB: Seafloor hydrothermal systems related to volcanic arcs are known from several localities in the Tyrrhenian Sea in water depths ranging from 650 m (Palinuro Seamount) to less than 50 m (Panarea). At Palinuro Seamount 13 holes (<5m) were drilled using Rockdrill 1 of the British Geological Survey 1 into the heavily sediment-covered deposit recovering 11 m of semi-massive to massive sulfides. Maximum recovery within a single core was 4.8 m of massive sulfides/sulfates with abundant late native sulfur overprint. The deposit is open to all sides and to depth since all drill holes ended in mineralization. Metal enrichment at the top of the deposit is evident in some cores with polymetallic (Zn, Pb, Ag) sulfides overlying more massive and dense pyritic ore. The massive sulfide mineralization at Palinuro Seamount contains a number of unusual minerals, including enargite, tennantite, luzonite, and Ag-sulfosalts, that are not commonly encountered in mid-ocean ridge massive sulfides. In analogy to epithermal deposits forming on land, the occurrence of these minerals suggests a high sulfidation state of the hydrothermal fluids during deposition implying that the mineralizing fluids were acidic and oxidizing rather than near-neutral and reducing as those forming typical base metal rich massive sulfides along mid-ocean ridges. Oxidizing conditions during sulfide deposition can probably be related to the presence of magmatic volatiles in the mineralizing fluids that may be derived from a degassing magma chamber. Elevated temperatures within sediment cores and TV-grab stations (up to 60°C) indicate present day hydrothermal fluid flow. This is also indicated by the presence of small tube-worm bushes present on top the sediment. A number of drill holes were placed around the known phreatic gas-rich vents of Panarea and recovered intense clay-alteration in some holes as well as abundant massive anhydrite/gypsum with only trace sulfides along a structural depression suggesting the presence of an anhydrite seal to a larger hydrothermal system at depth. The aim of this study is to understand the role that magmatic volatiles and phase separation play in the formation of these precious and trace element-rich shallow water (<750m) hydrothermal systems in the volcanic arcs of the Tyrrhenian Sea.
DE: 3001 Back-arc basin processes
DE: 3017 Hydrothermal systems (0450, 1034, 3616, 4832, 8135, 8424)
DE: 3665 Mineral occurrences and deposits
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2007 Fall Meeting