Mark Schmidt - Academia.edu (original) (raw)
Papers by Mark Schmidt
Gravity cores were collected during SONNE Cruise SO173/3 and METEOR Cruise M54/3 offshore Nicarag... more Gravity cores were collected during SONNE Cruise SO173/3 and METEOR Cruise M54/3 offshore Nicaragua and Costa Rica on the lower continental slope and on the ocean plate, at distances of 150-350 km to the Central American Volcanic Arc (CAVA). Thirteen core ...
... Kutterolf, Steffen, Schacht, U., Freundt, Armin, Wehrmann, Heidi, Mörz, T., Schmidt, M. and S... more ... Kutterolf, Steffen, Schacht, U., Freundt, Armin, Wehrmann, Heidi, Mörz, T., Schmidt, M. and Schmincke, Hans-Ulrich (2005) Vulkanische Aschen im pazifischen Ozean vor Nicaragua undCosta Rica - Ergebnisse der Sonne Ausfahrt SO 173/3 [Talk] In: SONNE Statusseminar, 09 ...
ABSTRACT Within subduction zones of active continental margins, large amounts of methane can be m... more ABSTRACT Within subduction zones of active continental margins, large amounts of methane can be mobilized by dewatering processes and transported to the seafloor along migration pathways. A recently discovered seep area located off Concepción (Chile) at water depth between 600 to 1100 mbsl is characterized by active methane vent sites as well as massive carbonates boulders and plates which probably are related to methane seepage in the past. During the SO210 research expedition "Chiflux" (Sept-Oct 2010), sediment from the Concepción Methane Seep Area (CSMA) at the fore arc of the Chilean margin was sampled to study microbial activity related to methane seepage. We sampled surface sediments (0-30cm) from sulfur bacteria mats, as well as clam, pogonophoran, and tubeworm fields with push cores and a TV-guided multicorer system. Anaerobic oxidation of methane (AOM) and sulfate reduction rates were determined using ex-situ radioisotope tracer techniques. Additionally, porewater chemistry of retrieved cores as well as isotopic composition and age record of surrounding authigenic carbonates were analyzed. The shallowest sulfate-methane-transition zone (SMTZ) was identified at 4 cm sediment depth hinting to locally strong fluid fluxes. However, a lack of Cl- anomalies in porewater profiles indicates a shallow source of these fluids, which is supported by the biogenic origin of the methane (δ13C -70‰ PDB). Sulfide and alkalinity was relatively high (up to 20 mM and 40 mEq, respectively). Rates of AOM and sulfate reduction within this area reached magnitudes typical for seeps with variation between different habitat types, indicating a diverse methane supply, which is affecting the depths of the SMTZ. Rates were highest at sulfur a bacteria mats (20 mmol m-2 d-1) followed by a large field of dead clams, a pogonophoran field, a black sediment spot, and a carbonate rich clam field. Lowest rates (0.2 mmol m-2 d-1) were measured in close vicinity to these hot spots. Abundant massive carbonate blocks and plates hint to a very old seep system with a probably much higher activity in the past. The U-Th age record of these authigenic carbonates reach back to periods of venting activity with more than 150 ka ago. Carbon isotopic signatures of authigenic carbonates (δ13C -50 to -40‰ PDB) suggest a biogenic carbon source (i.e. methane), also in the past. We found several indications for the impact of recent earthquakes within the seep area (cracks, shifted seafloor), which could be an important mechanism for the triggering of new seepage activity, change in fluid expulsion rates and colonization patterns of the cold seep fauna.
Geochimica Et Cosmochimica Acta 69 Pp 4665 4674, Oct 1, 2005
Hydrous CaMg-carbonate was synthesized at temperatures of 40°, 60° and 80°C in the laboratory. Th... more Hydrous CaMg-carbonate was synthesized at temperatures of 40°, 60° and 80°C in the laboratory. This material has very similar mineralogical characteristics to natural disordered dolomite from the Coorong region in South Australia. Besides the dolomite variable amounts of amorphous carbonate are present in all samples. The oxygen isotope compositions of synthesized bulk carbonate samples (e.g., amorphous carbonate plus dolomite) plot significantly lower than the Northrop and Clayton (1966) dolomite-water equilibrium. Fractionated degassing of the samples, however, revealed relatively low oxygen isotope values for fast-reacting (using 100% H 3PO 4) amorphous carbonate. In contrast, slow-reacting dolomite has more positive oxygen isotope values, and calculated carbonate-water oxygen isotope fractionation values are close to strongest known dolomite-water oxygen isotope fractionation published earlier on. Variations of reaction/stabilization temperatures during synthesis gave evidence for dolomite formation from hypersaline solutions by a dissolution/reprecipitation process. It is likely that amorphous carbonate has been a problem in defining the dolomite-water fractionation in the past. Moreover, dolomite-associated amorphous carbonate contents probably led to incorrect speculations about lower oxygen isotope fractionation in a so-called protodolomite-water system.
Geochimica Et Cosmochimica Acta 100 Pp 200 216, 2013
Chemical Geology 249 Pp 321 338 Doi 10 1016 J Chemgeo 2008 01 026, Apr 1, 2008
Four volcanic ash-bearing marine sediment cores and one ash-free reference core were examined dur... more Four volcanic ash-bearing marine sediment cores and one ash-free reference core were examined during research cruise RV Meteor 54/2 offshore Nicaragua and Costa Rica to investigate the chemical composition of pore waters related to volcanic ash alteration.Sediments were composed of terrigenous matter derived from the adjacent continent and contained several distinct ash layers. Biogenic opal and carbonate were only minor
Earth and Planetary Science Letters, Aug 1, 1998
Oxygen isotope ratios were obtained from authigenic clinoptilolites from Barbados Accretionary Co... more Oxygen isotope ratios were obtained from authigenic clinoptilolites from Barbados Accretionary Complex, Yamato Basin, and Exmouth Plateau sediments (ODP Sites 672, 797, and 762) in order to investigate the isotopic fractionation between clinoptilolite and pore water at early diagenetic stages and low temperatures. Dehydrated clinoptilolites display isotopic ratios for the zeolite framework ( δ18O f) that extend from +18.7‰ to +32.8‰ (vs. SMOW). In combination with associated pore water isotope data, the oxygen isotopic fractionation between clinoptilolite and pore fluids could be assessed in the temperature range from 25°C to 40°C. The resulting fractionation factors of 1.032 at 25°C and 1.027 at 40°C are in good agreement with the theoretically determined oxygen isotope fractionation between clinoptilolite and water. Calculations of isotopic temperatures illustrate that clinoptilolite formation occurred at relatively low temperatures of 17°C to 29°C in Barbados Ridge sediments and at 33°C to 62°C in the Yamato Basin. These data support a low-temperature origin of clinoptilolite and contradict the assumption that elevated temperatures are the main controlling factor for authigenic clinoptilolite formation. Increasing clinoptilolite δ18O f values with depth indicate that clinoptilolites which are now in the deeper parts of the zeolite-bearing intervals had either formed at lower temperatures (17-20°C) or under closed system conditions.
Marine Geology, 2005
... Authigenic phyllosilicates are commonly described in submarine hydrothermal systems (Hekinian... more ... Authigenic phyllosilicates are commonly described in submarine hydrothermal systems (Hekinian et al., 1978, McMurtry and Yeh, 1981, De Carlo et al., 1983, Honnorez et al., 1983, McMurtry et al., 1983, Murnane and Clague, 1983, Alt et al., 1986, Alt, 1988, Stoffers et al., 1990 ...
Marine Technology Society Journal, 2015
During RV Poseidon cruise POS469 (May 2014), the distribution of pCO 2 in the near field of subma... more During RV Poseidon cruise POS469 (May 2014), the distribution of pCO 2 in the near field of submarine volcanic gas flares in shallow water depths down to 50 m below sea level was continuously monitored using three different and independent methodologies. In situ nondispersive infrared (NDIR) spectrometry, pH measurements, and onboard membrane inlet mass spectrometry (MIMS) were used to determine the fate of rising CO 2 bubbles and the dissolved CO 2 plume patterns in a 300 × 400-m working area. The in situ sensor carrier platform, a towed video-controlled water sampling rosette, equipped with CTD sensors, guaranteed excellent ground truthing of seafloor characteristics and bubble discharge. Sensor data and nearseafloor observations indicated that the gas bubbles (<9 mm in diameter, >97 vol.% of CO 2 ) dissolved very rapidly within the first 10 m above seafloor. Bottom water masses enriched with pCO 2 (up to 1,100 μatm) show low pH values (up to 7.80) and tend to spread rather downslope west than following the measured weak current in SSE-SSW direction. The 3-D evaluation of pCO 2 plume is a valuable tool to backtrace the origin of CO 2 leakage when compared with local current regimes, water column CTD data, and seafloor bathymetry. Seep sites offshore Panarea can be used for studying CO 2 leakage behavior and testing measuring strategies in shallow waters. Moreover, this area is a naturally designed laboratory to improve existing physicochemical and oceanographic transport models for subsea CO 2 leakage.
Gravity cores were collected during SONNE Cruise SO173/3 and METEOR Cruise M54/3 offshore Nicarag... more Gravity cores were collected during SONNE Cruise SO173/3 and METEOR Cruise M54/3 offshore Nicaragua and Costa Rica on the lower continental slope and on the ocean plate, at distances of 150-350 km to the Central American Volcanic Arc (CAVA). Thirteen core ...
... Kutterolf, Steffen, Schacht, U., Freundt, Armin, Wehrmann, Heidi, Mörz, T., Schmidt, M. and S... more ... Kutterolf, Steffen, Schacht, U., Freundt, Armin, Wehrmann, Heidi, Mörz, T., Schmidt, M. and Schmincke, Hans-Ulrich (2005) Vulkanische Aschen im pazifischen Ozean vor Nicaragua undCosta Rica - Ergebnisse der Sonne Ausfahrt SO 173/3 [Talk] In: SONNE Statusseminar, 09 ...
ABSTRACT Within subduction zones of active continental margins, large amounts of methane can be m... more ABSTRACT Within subduction zones of active continental margins, large amounts of methane can be mobilized by dewatering processes and transported to the seafloor along migration pathways. A recently discovered seep area located off Concepción (Chile) at water depth between 600 to 1100 mbsl is characterized by active methane vent sites as well as massive carbonates boulders and plates which probably are related to methane seepage in the past. During the SO210 research expedition "Chiflux" (Sept-Oct 2010), sediment from the Concepción Methane Seep Area (CSMA) at the fore arc of the Chilean margin was sampled to study microbial activity related to methane seepage. We sampled surface sediments (0-30cm) from sulfur bacteria mats, as well as clam, pogonophoran, and tubeworm fields with push cores and a TV-guided multicorer system. Anaerobic oxidation of methane (AOM) and sulfate reduction rates were determined using ex-situ radioisotope tracer techniques. Additionally, porewater chemistry of retrieved cores as well as isotopic composition and age record of surrounding authigenic carbonates were analyzed. The shallowest sulfate-methane-transition zone (SMTZ) was identified at 4 cm sediment depth hinting to locally strong fluid fluxes. However, a lack of Cl- anomalies in porewater profiles indicates a shallow source of these fluids, which is supported by the biogenic origin of the methane (δ13C -70‰ PDB). Sulfide and alkalinity was relatively high (up to 20 mM and 40 mEq, respectively). Rates of AOM and sulfate reduction within this area reached magnitudes typical for seeps with variation between different habitat types, indicating a diverse methane supply, which is affecting the depths of the SMTZ. Rates were highest at sulfur a bacteria mats (20 mmol m-2 d-1) followed by a large field of dead clams, a pogonophoran field, a black sediment spot, and a carbonate rich clam field. Lowest rates (0.2 mmol m-2 d-1) were measured in close vicinity to these hot spots. Abundant massive carbonate blocks and plates hint to a very old seep system with a probably much higher activity in the past. The U-Th age record of these authigenic carbonates reach back to periods of venting activity with more than 150 ka ago. Carbon isotopic signatures of authigenic carbonates (δ13C -50 to -40‰ PDB) suggest a biogenic carbon source (i.e. methane), also in the past. We found several indications for the impact of recent earthquakes within the seep area (cracks, shifted seafloor), which could be an important mechanism for the triggering of new seepage activity, change in fluid expulsion rates and colonization patterns of the cold seep fauna.
Geochimica Et Cosmochimica Acta 69 Pp 4665 4674, Oct 1, 2005
Hydrous CaMg-carbonate was synthesized at temperatures of 40°, 60° and 80°C in the laboratory. Th... more Hydrous CaMg-carbonate was synthesized at temperatures of 40°, 60° and 80°C in the laboratory. This material has very similar mineralogical characteristics to natural disordered dolomite from the Coorong region in South Australia. Besides the dolomite variable amounts of amorphous carbonate are present in all samples. The oxygen isotope compositions of synthesized bulk carbonate samples (e.g., amorphous carbonate plus dolomite) plot significantly lower than the Northrop and Clayton (1966) dolomite-water equilibrium. Fractionated degassing of the samples, however, revealed relatively low oxygen isotope values for fast-reacting (using 100% H 3PO 4) amorphous carbonate. In contrast, slow-reacting dolomite has more positive oxygen isotope values, and calculated carbonate-water oxygen isotope fractionation values are close to strongest known dolomite-water oxygen isotope fractionation published earlier on. Variations of reaction/stabilization temperatures during synthesis gave evidence for dolomite formation from hypersaline solutions by a dissolution/reprecipitation process. It is likely that amorphous carbonate has been a problem in defining the dolomite-water fractionation in the past. Moreover, dolomite-associated amorphous carbonate contents probably led to incorrect speculations about lower oxygen isotope fractionation in a so-called protodolomite-water system.
Geochimica Et Cosmochimica Acta 100 Pp 200 216, 2013
Chemical Geology 249 Pp 321 338 Doi 10 1016 J Chemgeo 2008 01 026, Apr 1, 2008
Four volcanic ash-bearing marine sediment cores and one ash-free reference core were examined dur... more Four volcanic ash-bearing marine sediment cores and one ash-free reference core were examined during research cruise RV Meteor 54/2 offshore Nicaragua and Costa Rica to investigate the chemical composition of pore waters related to volcanic ash alteration.Sediments were composed of terrigenous matter derived from the adjacent continent and contained several distinct ash layers. Biogenic opal and carbonate were only minor
Earth and Planetary Science Letters, Aug 1, 1998
Oxygen isotope ratios were obtained from authigenic clinoptilolites from Barbados Accretionary Co... more Oxygen isotope ratios were obtained from authigenic clinoptilolites from Barbados Accretionary Complex, Yamato Basin, and Exmouth Plateau sediments (ODP Sites 672, 797, and 762) in order to investigate the isotopic fractionation between clinoptilolite and pore water at early diagenetic stages and low temperatures. Dehydrated clinoptilolites display isotopic ratios for the zeolite framework ( δ18O f) that extend from +18.7‰ to +32.8‰ (vs. SMOW). In combination with associated pore water isotope data, the oxygen isotopic fractionation between clinoptilolite and pore fluids could be assessed in the temperature range from 25°C to 40°C. The resulting fractionation factors of 1.032 at 25°C and 1.027 at 40°C are in good agreement with the theoretically determined oxygen isotope fractionation between clinoptilolite and water. Calculations of isotopic temperatures illustrate that clinoptilolite formation occurred at relatively low temperatures of 17°C to 29°C in Barbados Ridge sediments and at 33°C to 62°C in the Yamato Basin. These data support a low-temperature origin of clinoptilolite and contradict the assumption that elevated temperatures are the main controlling factor for authigenic clinoptilolite formation. Increasing clinoptilolite δ18O f values with depth indicate that clinoptilolites which are now in the deeper parts of the zeolite-bearing intervals had either formed at lower temperatures (17-20°C) or under closed system conditions.
Marine Geology, 2005
... Authigenic phyllosilicates are commonly described in submarine hydrothermal systems (Hekinian... more ... Authigenic phyllosilicates are commonly described in submarine hydrothermal systems (Hekinian et al., 1978, McMurtry and Yeh, 1981, De Carlo et al., 1983, Honnorez et al., 1983, McMurtry et al., 1983, Murnane and Clague, 1983, Alt et al., 1986, Alt, 1988, Stoffers et al., 1990 ...
Marine Technology Society Journal, 2015
During RV Poseidon cruise POS469 (May 2014), the distribution of pCO 2 in the near field of subma... more During RV Poseidon cruise POS469 (May 2014), the distribution of pCO 2 in the near field of submarine volcanic gas flares in shallow water depths down to 50 m below sea level was continuously monitored using three different and independent methodologies. In situ nondispersive infrared (NDIR) spectrometry, pH measurements, and onboard membrane inlet mass spectrometry (MIMS) were used to determine the fate of rising CO 2 bubbles and the dissolved CO 2 plume patterns in a 300 × 400-m working area. The in situ sensor carrier platform, a towed video-controlled water sampling rosette, equipped with CTD sensors, guaranteed excellent ground truthing of seafloor characteristics and bubble discharge. Sensor data and nearseafloor observations indicated that the gas bubbles (<9 mm in diameter, >97 vol.% of CO 2 ) dissolved very rapidly within the first 10 m above seafloor. Bottom water masses enriched with pCO 2 (up to 1,100 μatm) show low pH values (up to 7.80) and tend to spread rather downslope west than following the measured weak current in SSE-SSW direction. The 3-D evaluation of pCO 2 plume is a valuable tool to backtrace the origin of CO 2 leakage when compared with local current regimes, water column CTD data, and seafloor bathymetry. Seep sites offshore Panarea can be used for studying CO 2 leakage behavior and testing measuring strategies in shallow waters. Moreover, this area is a naturally designed laboratory to improve existing physicochemical and oceanographic transport models for subsea CO 2 leakage.