In December 1993, the ®rst massive sul®des were recovered from the Indian Ocean¯oor, north of the... more In December 1993, the ®rst massive sul®des were recovered from the Indian Ocean¯oor, north of the Rodrigues Triple Junction. The polymetallic deposit is situated in the fourth Central Indian Ridge segment, close to the rift axis; it is hydrothermally no longer active. The deposit appears to be typical of mid-ocean ridge massive sul®de occurrences but is in a phase of disintegration and about to be buried by sediment. The chimney structures were formed by multiple hydrothermal events and are now degraded by mass wasting showing various stages of weathering. Later-stage, low-temperature hydrothermal mineralization processes led to copper and gold enrichment. Here we report on the geological setting, mineral zonation, dierent sul®de types and stages of formation of the``Sonne Sul®de Field'', which is part of a larger mineralized zone.
Richa t, Maure tanien / Lands at 7 / USGS / NASA D i e E r d e i m V i s i e r Die Be ob ach tun ... more Richa t, Maure tanien / Lands at 7 / USGS / NASA D i e E r d e i m V i s i e r Die Be ob ach tun g de s Sy ste ms Erd e au s de m We ltr au m Ka tal og zu r Wa nd era us ste llu ng Ka tal og zu r Wa nd era us ste llu ng Ka tal og zu r Wa nd era us ste llu ng
The German-Indonesian Tsunami Early Warning System (GITEWS) for the Indian Ocean region has gone ... more The German-Indonesian Tsunami Early Warning System (GITEWS) for the Indian Ocean region has gone into operation in Indonesia in November 2008. The system includes a seismological network, together with GPS stations and a network of GPS buoys additionally equipped with ocean bottom pressure sensors and a tide gauge network. The different sensor systems have, for the most part, been installed and now deliver respective data either online or interactively upon request to the Warning Centre in Jakarta. Before 2011, however, the different components requires further optimization and fine tuning, local personnel needs to be trained and eventual problems in the daily operation have to be dealt with. Furthermore a company will be founded in the near future, which will guarantee a sustainable maintenance and operation of the system. This concludes the transfer from a temporarily project into a permanent service. This system established in Indonesia differs from other Tsunami Warning Systems ...
The Tsunami Early Warning System for the Indian Ocean just recently went into operation in Indone... more The Tsunami Early Warning System for the Indian Ocean just recently went into operation in Indonesia. The different sensor stations have, for the most part, been installed and now deliver respective data either online or upon request to the Warning Centre in Jakarta. Before March 2010, however, the interaction between the different component parts must be improved and optimized, personnel needs to be trained and eventual problems in the daily operation have to be dealt with. This current system differs from previous Tsunami Warning Systems through the application of modern scientific methods and technologies. New procedures for the fast and reliable determination of strong earthquakes, the modelling of tsunamis and the assessment of the situation have been implemented in the Warning System. In particular, the direct incorporation of a broad variety of different sensors provides for information from a number of sources thus resulting in a stable system and minimizing breakdowns. The ...
Although hydrothermal activity is well documented from many fields on most mid-ocean ridges, no h... more Although hydrothermal activity is well documented from many fields on most mid-ocean ridges, no hydrothermally mineralized area was known from the ultraslow spreading Southwest Indian Ridge since October 1998 when RV Yokosuka with the submersible Shinkai 6500 investigated in this area. This newly discovered massive sulfide field is located near 27°51S/63°56E in the 11 th segment west of the Rodriguez Triple Junction.
ABSTRACT Modern massive sulfide deposits are known to occur in diverse tectonic settings and it i... more ABSTRACT Modern massive sulfide deposits are known to occur in diverse tectonic settings and it is generally expected that hydrothermal deposits of similar geological settings shall have more or less similar mineralogical and geochemical signatures. However, the Mount Jourdanne sulfide deposits along the super-slow spreading Southwest Indian Ridge deviate from this common concept. These sulfide precipitates are Zn-rich (up to 35 wt.%) and are characterized by high concentrations of Pb (≤ 3.5 wt.%), As (≤ 1.1 wt.%), Ag (≤ 0.12 wt.%), Au (≤ 11 ppm), Sb (≤ 967 ppm), and Cd (≤ 0.2 wt.%) which are unusual for a modern sediment-free mid-oceanic ridge system. Therefore, we have reinvestigated the sulfide samples collected during the INDOYO cruise in 1998, in order to explain their unusual mineralogy and geochemical composition. The sulfide samples are polymetallic and are classified as: a) chimneys, b) mounds, and c) hydrothermal breccias. The chimneys are small tube-like symmetrical bodies (30–40 cm high; ~ 10 cm diameter) and consist mainly of sphalerite and less chalcopyrite, set in a matrix of late amorphous silica. The inner wall shows a late-stage colloform sphalerite containing co-precipitates of galena and/or Pb–As sulfosalts. In contrast, the mound samples are dominated either by Fe-sulfides (pyrite) or by a mixture of pyrite and chalcopyrite with less sphalerite, pyrrhotite, amorphous silica and barite. Both, the chimney and mound samples, are characterized by layering and mineral zonation. The hydrothermal breccias are highly altered and mineralogically heterogeneous. They consist of silicified basaltic material that are impregnated with sulfides and contain cm-sized chimney fragments within a matrix of low-temperature minerals such as sphalerite and pyrite. The latter fragments mainly consist of chalcopyrite with isocubanite lamellae. In addition, these breccias contain late-stage realgar, boulangerite, galena, Pb–As sulfosalts and barite that are mostly confined to vugs or fractures. At least five mineralogical associations are distinguished that indicate different thermal episodes ranging from black smoker mineralization conditions to cessation of the hydrothermal activity. Based on the mineralogical associations and established literature in this regard, it is inferred that the mineralization at Mt. Jourdanne occurred mainly in three temperature domains. Above 300 °C, the chalcopyrite (with isocubanite)–pyrrhotite association formed whereas the sphalerite dominated assemblage with much less chalcopyrite and pyrite formed around and below 300 °C. The late-stage mineralization (below 200 °C) contains colloform sphalerite, galena, Pb–As sulfosalts, realgar and barite. The unusual mineralogy and trace element chemistry for this modern VHMS deposit could be explained assuming hydrothermal leaching of some felsic differentiates underneath the basaltic cover and subsequent zone refining processes.
... Other key milestones such as the development of the automatic data processing softwareSeisCom... more ... Other key milestones such as the development of the automatic data processing softwareSeisComP3, and the underwater communication for the transmission of the pressure data from the ocean floor to a warning centre are successfully realised. ...
In December 1993, the ®rst massive sul®des were recovered from the Indian Ocean¯oor, north of the... more In December 1993, the ®rst massive sul®des were recovered from the Indian Ocean¯oor, north of the Rodrigues Triple Junction. The polymetallic deposit is situated in the fourth Central Indian Ridge segment, close to the rift axis; it is hydrothermally no longer active. The deposit appears to be typical of mid-ocean ridge massive sul®de occurrences but is in a phase of disintegration and about to be buried by sediment. The chimney structures were formed by multiple hydrothermal events and are now degraded by mass wasting showing various stages of weathering. Later-stage, low-temperature hydrothermal mineralization processes led to copper and gold enrichment. Here we report on the geological setting, mineral zonation, dierent sul®de types and stages of formation of the``Sonne Sul®de Field'', which is part of a larger mineralized zone.
ABSTRACT Hydrothermal activity in the Indian Ocean has hitherto only been poorly documented. Firs... more ABSTRACT Hydrothermal activity in the Indian Ocean has hitherto only been poorly documented. First indications of hydrothermal mineralization were observed in 1987 during the GEMINO-cruise over the 4th ridge segment of the Central Indian Ridge, 270 km north of the Rodriguez Triple Junction. Subsequent cruises in 1993 (HYDROTRUNC) and in 1995 (HYDROCK) were carried out in order to obtain detailed information about the geological setting and the extent and mineral distribution of the field, but primarily to sample the first massive sulfides of the Indian Ocean floor. This hydrothermal field, which was called the MESO zone, was studied by detailed mapping and by ocean bottom photography. Hydrothermal precipitates were recovered with a TV-grab sampler at four sampling locations, two in the northern part of the mineralized field, called the Talus Tips Site, and two in the central part, called the Sonne Field. The sulfide samples were age-dated using the 230Th/234U method. They show different periods of activity at each site: 52±5, 22.7±3 and 16±2 ka for the main events at the Talus Tips Site and 18±2 and 12.5±1.5 ka for the Sonne Field. We conclude from these data that the two sites were not active at the same time. If it is assumed that there is a complete cessation of activity between 52 and 23 ka, for more recent periods (from 23 to 10 ka) it may be postulated that the deep-seated hydrothermal circulation is continuous but that the discharge of hot fluid occurs alternately at the Sonne Field or at the Talus Tips Site. Comparing our results with those obtained previously at the different hydrothermal sites, we favor the conclusion of episodic activity. Moreover, in the Sonne Field, jasper formation resulting from a low-temperature hydrothermal event dated at around 11 ka is presently the youngest hydrothermal formation in the entire MESO zone.
During the Indoyo cruise in 1998 with Shinkai 6500 a massive sulfide field was located in a water... more During the Indoyo cruise in 1998 with Shinkai 6500 a massive sulfide field was located in a water depth of about 2940 m, near 27851 X Sr63856 X E, east of the Melville fracture zone. The newly discovered hydrothermal field is situated at the summit of an axial volcanic ridge, informally called, Mount Jourdanne. Within the field, inactive chimneys as well as hydrothermal mounds were observed on the ocean floor but no indications such as shimmering water, chemical anomalies in the water column or faunal relicts, which might point to an active vent site, were observed.
... (f) Fossil worm tube is lined with layered pyrite and filled with chalcopyrite and amorphous ... more ... (f) Fossil worm tube is lined with layered pyrite and filled with chalcopyrite and amorphous silica (24-4.37). (g) Small inclusions of chalcopyrite in sphalerite (24-2.8). ... Fossil worm tubes were recognized in several samples (personal communication: Dr. C. Little; Fig. ...
The system conception combines terrestrial observation networks of seismology and geodesy with oc... more The system conception combines terrestrial observation networks of seismology and geodesy with oceanographic instrumentation such as tide gauges and buoys and is installed mostly in Indonesia, but also in adjacent countries. GITEWS is realized as an open system to ensure that different components or sensors respectively, can be added if necessary to extend the fields of application later (multi-hazard, eastern coastlines of Indonesia). In 90% a tsunami is caused by a submarine earthquake. Therefore a fast and correct seismological recording and evaluation is the most important requirement for the warning system. The biggest challenge is the fast failure-free recording and the exact quantification of strong quakes. With the seismic sensors installed so far in Indonesia and with the GFZ developed software system SeisComP3, a reliable tool to quickly register and evaluate even strong earthquakes is now available. Meanwhile SeisComP3 is established as standard in several countries around the Indian Ocean such as in the Indian tsunami warning centre at INCOIS. Based on seismological measurements only it is not possible to decide whether a tsunami has been generated or not. Therefore the detection of a tsunami is carried out directly on the ocean floor and surface using ocean bottom units, buoys and tide gauges. The buoys have two functions: besides the "classical" DART ocean bottom pressure recording functionality they are equipped with near-realtime GPS functionality so that it is additional possible to detect sea level anomalies at the surface using the buoy itself as a gauge. In addition near real time GPS stations along the coast line are used for the detection of crustal movements shortly after an Earthquake. All different sensor data are collected in the warning centre in Jakarta, from here all instruments are controlled, data processing is done and using precalculated simulations a situation picture is generated. The selection process is based on all instrument inputs (seismolopgy, ocean instrumentation and GPS) to have already some minutes after an Earthquake a robust selection of a best fitting simulation. These different activities are integrated in a decision support centre, which provides the responsible officer with an overview of the available data, an assessment of the situation and proposals for decision. Besides the technical infrastructure for Early Warning, GITEWS also provides an education and training program for scientists, technicians, and local communities as well as for involved Indonesian institutions.
In December 1993, the ®rst massive sul®des were recovered from the Indian Ocean¯oor, north of the... more In December 1993, the ®rst massive sul®des were recovered from the Indian Ocean¯oor, north of the Rodrigues Triple Junction. The polymetallic deposit is situated in the fourth Central Indian Ridge segment, close to the rift axis; it is hydrothermally no longer active. The deposit appears to be typical of mid-ocean ridge massive sul®de occurrences but is in a phase of disintegration and about to be buried by sediment. The chimney structures were formed by multiple hydrothermal events and are now degraded by mass wasting showing various stages of weathering. Later-stage, low-temperature hydrothermal mineralization processes led to copper and gold enrichment. Here we report on the geological setting, mineral zonation, dierent sul®de types and stages of formation of the``Sonne Sul®de Field'', which is part of a larger mineralized zone.
Richa t, Maure tanien / Lands at 7 / USGS / NASA D i e E r d e i m V i s i e r Die Be ob ach tun ... more Richa t, Maure tanien / Lands at 7 / USGS / NASA D i e E r d e i m V i s i e r Die Be ob ach tun g de s Sy ste ms Erd e au s de m We ltr au m Ka tal og zu r Wa nd era us ste llu ng Ka tal og zu r Wa nd era us ste llu ng Ka tal og zu r Wa nd era us ste llu ng
The German-Indonesian Tsunami Early Warning System (GITEWS) for the Indian Ocean region has gone ... more The German-Indonesian Tsunami Early Warning System (GITEWS) for the Indian Ocean region has gone into operation in Indonesia in November 2008. The system includes a seismological network, together with GPS stations and a network of GPS buoys additionally equipped with ocean bottom pressure sensors and a tide gauge network. The different sensor systems have, for the most part, been installed and now deliver respective data either online or interactively upon request to the Warning Centre in Jakarta. Before 2011, however, the different components requires further optimization and fine tuning, local personnel needs to be trained and eventual problems in the daily operation have to be dealt with. Furthermore a company will be founded in the near future, which will guarantee a sustainable maintenance and operation of the system. This concludes the transfer from a temporarily project into a permanent service. This system established in Indonesia differs from other Tsunami Warning Systems ...
The Tsunami Early Warning System for the Indian Ocean just recently went into operation in Indone... more The Tsunami Early Warning System for the Indian Ocean just recently went into operation in Indonesia. The different sensor stations have, for the most part, been installed and now deliver respective data either online or upon request to the Warning Centre in Jakarta. Before March 2010, however, the interaction between the different component parts must be improved and optimized, personnel needs to be trained and eventual problems in the daily operation have to be dealt with. This current system differs from previous Tsunami Warning Systems through the application of modern scientific methods and technologies. New procedures for the fast and reliable determination of strong earthquakes, the modelling of tsunamis and the assessment of the situation have been implemented in the Warning System. In particular, the direct incorporation of a broad variety of different sensors provides for information from a number of sources thus resulting in a stable system and minimizing breakdowns. The ...
Although hydrothermal activity is well documented from many fields on most mid-ocean ridges, no h... more Although hydrothermal activity is well documented from many fields on most mid-ocean ridges, no hydrothermally mineralized area was known from the ultraslow spreading Southwest Indian Ridge since October 1998 when RV Yokosuka with the submersible Shinkai 6500 investigated in this area. This newly discovered massive sulfide field is located near 27°51S/63°56E in the 11 th segment west of the Rodriguez Triple Junction.
ABSTRACT Modern massive sulfide deposits are known to occur in diverse tectonic settings and it i... more ABSTRACT Modern massive sulfide deposits are known to occur in diverse tectonic settings and it is generally expected that hydrothermal deposits of similar geological settings shall have more or less similar mineralogical and geochemical signatures. However, the Mount Jourdanne sulfide deposits along the super-slow spreading Southwest Indian Ridge deviate from this common concept. These sulfide precipitates are Zn-rich (up to 35 wt.%) and are characterized by high concentrations of Pb (≤ 3.5 wt.%), As (≤ 1.1 wt.%), Ag (≤ 0.12 wt.%), Au (≤ 11 ppm), Sb (≤ 967 ppm), and Cd (≤ 0.2 wt.%) which are unusual for a modern sediment-free mid-oceanic ridge system. Therefore, we have reinvestigated the sulfide samples collected during the INDOYO cruise in 1998, in order to explain their unusual mineralogy and geochemical composition. The sulfide samples are polymetallic and are classified as: a) chimneys, b) mounds, and c) hydrothermal breccias. The chimneys are small tube-like symmetrical bodies (30–40 cm high; ~ 10 cm diameter) and consist mainly of sphalerite and less chalcopyrite, set in a matrix of late amorphous silica. The inner wall shows a late-stage colloform sphalerite containing co-precipitates of galena and/or Pb–As sulfosalts. In contrast, the mound samples are dominated either by Fe-sulfides (pyrite) or by a mixture of pyrite and chalcopyrite with less sphalerite, pyrrhotite, amorphous silica and barite. Both, the chimney and mound samples, are characterized by layering and mineral zonation. The hydrothermal breccias are highly altered and mineralogically heterogeneous. They consist of silicified basaltic material that are impregnated with sulfides and contain cm-sized chimney fragments within a matrix of low-temperature minerals such as sphalerite and pyrite. The latter fragments mainly consist of chalcopyrite with isocubanite lamellae. In addition, these breccias contain late-stage realgar, boulangerite, galena, Pb–As sulfosalts and barite that are mostly confined to vugs or fractures. At least five mineralogical associations are distinguished that indicate different thermal episodes ranging from black smoker mineralization conditions to cessation of the hydrothermal activity. Based on the mineralogical associations and established literature in this regard, it is inferred that the mineralization at Mt. Jourdanne occurred mainly in three temperature domains. Above 300 °C, the chalcopyrite (with isocubanite)–pyrrhotite association formed whereas the sphalerite dominated assemblage with much less chalcopyrite and pyrite formed around and below 300 °C. The late-stage mineralization (below 200 °C) contains colloform sphalerite, galena, Pb–As sulfosalts, realgar and barite. The unusual mineralogy and trace element chemistry for this modern VHMS deposit could be explained assuming hydrothermal leaching of some felsic differentiates underneath the basaltic cover and subsequent zone refining processes.
... Other key milestones such as the development of the automatic data processing softwareSeisCom... more ... Other key milestones such as the development of the automatic data processing softwareSeisComP3, and the underwater communication for the transmission of the pressure data from the ocean floor to a warning centre are successfully realised. ...
In December 1993, the ®rst massive sul®des were recovered from the Indian Ocean¯oor, north of the... more In December 1993, the ®rst massive sul®des were recovered from the Indian Ocean¯oor, north of the Rodrigues Triple Junction. The polymetallic deposit is situated in the fourth Central Indian Ridge segment, close to the rift axis; it is hydrothermally no longer active. The deposit appears to be typical of mid-ocean ridge massive sul®de occurrences but is in a phase of disintegration and about to be buried by sediment. The chimney structures were formed by multiple hydrothermal events and are now degraded by mass wasting showing various stages of weathering. Later-stage, low-temperature hydrothermal mineralization processes led to copper and gold enrichment. Here we report on the geological setting, mineral zonation, dierent sul®de types and stages of formation of the``Sonne Sul®de Field'', which is part of a larger mineralized zone.
ABSTRACT Hydrothermal activity in the Indian Ocean has hitherto only been poorly documented. Firs... more ABSTRACT Hydrothermal activity in the Indian Ocean has hitherto only been poorly documented. First indications of hydrothermal mineralization were observed in 1987 during the GEMINO-cruise over the 4th ridge segment of the Central Indian Ridge, 270 km north of the Rodriguez Triple Junction. Subsequent cruises in 1993 (HYDROTRUNC) and in 1995 (HYDROCK) were carried out in order to obtain detailed information about the geological setting and the extent and mineral distribution of the field, but primarily to sample the first massive sulfides of the Indian Ocean floor. This hydrothermal field, which was called the MESO zone, was studied by detailed mapping and by ocean bottom photography. Hydrothermal precipitates were recovered with a TV-grab sampler at four sampling locations, two in the northern part of the mineralized field, called the Talus Tips Site, and two in the central part, called the Sonne Field. The sulfide samples were age-dated using the 230Th/234U method. They show different periods of activity at each site: 52±5, 22.7±3 and 16±2 ka for the main events at the Talus Tips Site and 18±2 and 12.5±1.5 ka for the Sonne Field. We conclude from these data that the two sites were not active at the same time. If it is assumed that there is a complete cessation of activity between 52 and 23 ka, for more recent periods (from 23 to 10 ka) it may be postulated that the deep-seated hydrothermal circulation is continuous but that the discharge of hot fluid occurs alternately at the Sonne Field or at the Talus Tips Site. Comparing our results with those obtained previously at the different hydrothermal sites, we favor the conclusion of episodic activity. Moreover, in the Sonne Field, jasper formation resulting from a low-temperature hydrothermal event dated at around 11 ka is presently the youngest hydrothermal formation in the entire MESO zone.
During the Indoyo cruise in 1998 with Shinkai 6500 a massive sulfide field was located in a water... more During the Indoyo cruise in 1998 with Shinkai 6500 a massive sulfide field was located in a water depth of about 2940 m, near 27851 X Sr63856 X E, east of the Melville fracture zone. The newly discovered hydrothermal field is situated at the summit of an axial volcanic ridge, informally called, Mount Jourdanne. Within the field, inactive chimneys as well as hydrothermal mounds were observed on the ocean floor but no indications such as shimmering water, chemical anomalies in the water column or faunal relicts, which might point to an active vent site, were observed.
... (f) Fossil worm tube is lined with layered pyrite and filled with chalcopyrite and amorphous ... more ... (f) Fossil worm tube is lined with layered pyrite and filled with chalcopyrite and amorphous silica (24-4.37). (g) Small inclusions of chalcopyrite in sphalerite (24-2.8). ... Fossil worm tubes were recognized in several samples (personal communication: Dr. C. Little; Fig. ...
The system conception combines terrestrial observation networks of seismology and geodesy with oc... more The system conception combines terrestrial observation networks of seismology and geodesy with oceanographic instrumentation such as tide gauges and buoys and is installed mostly in Indonesia, but also in adjacent countries. GITEWS is realized as an open system to ensure that different components or sensors respectively, can be added if necessary to extend the fields of application later (multi-hazard, eastern coastlines of Indonesia). In 90% a tsunami is caused by a submarine earthquake. Therefore a fast and correct seismological recording and evaluation is the most important requirement for the warning system. The biggest challenge is the fast failure-free recording and the exact quantification of strong quakes. With the seismic sensors installed so far in Indonesia and with the GFZ developed software system SeisComP3, a reliable tool to quickly register and evaluate even strong earthquakes is now available. Meanwhile SeisComP3 is established as standard in several countries around the Indian Ocean such as in the Indian tsunami warning centre at INCOIS. Based on seismological measurements only it is not possible to decide whether a tsunami has been generated or not. Therefore the detection of a tsunami is carried out directly on the ocean floor and surface using ocean bottom units, buoys and tide gauges. The buoys have two functions: besides the "classical" DART ocean bottom pressure recording functionality they are equipped with near-realtime GPS functionality so that it is additional possible to detect sea level anomalies at the surface using the buoy itself as a gauge. In addition near real time GPS stations along the coast line are used for the detection of crustal movements shortly after an Earthquake. All different sensor data are collected in the warning centre in Jakarta, from here all instruments are controlled, data processing is done and using precalculated simulations a situation picture is generated. The selection process is based on all instrument inputs (seismolopgy, ocean instrumentation and GPS) to have already some minutes after an Earthquake a robust selection of a best fitting simulation. These different activities are integrated in a decision support centre, which provides the responsible officer with an overview of the available data, an assessment of the situation and proposals for decision. Besides the technical infrastructure for Early Warning, GITEWS also provides an education and training program for scientists, technicians, and local communities as well as for involved Indonesian institutions.
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