Blumenberg, Martin

Krueger, Martin

Mazzini, Adriano

Scheeder, Georg

OceanRep

Geophysical Research AbstractsVol. 19, EGU2017-6423-1, 2017EGU General Assembly 2017© Author(s) 2017. CC Attribution 3.0 License.Potential sources of hydrocarbons and their microbial degradation insediments from the deep geothermal Lusi site, IndonesiaMartin Krueger (1), Adriano Mazzini (2), Georg Scheeder (1), and Martin Blumenberg (1)(1) BGR, Resource Geochemistry, Hannover, Germany (martin.krueger@bgr.de), (2) Centre for Earth Evolution andDynamics (CEED) University of Oslo, Oslo, NorwayThe Lusi eruption represents one of the largest ongoing sedimentary hosted geothermal systems, which started in2006 following an earthquake on Java Island. Since then it has been continuously producing hot and hydrocarbonrich mud from a central crater with peaks reaching 180.000 m3 per day. Numerous investigations focused on thestudy of microbial communities which thrive at offshore methane and oil seeps and mud volcanoes, however verylittle has been done on onshore seeping structures. Lusi represents a unique opportunity to complete a compre-hensive study of onshore microbial communities fed by the seepage of CH4 as well as of liquid hydrocarbonsoriginating from one or more km below the surface. While the source of the methane at Lusi is unambiuous, theorigin of the seeping oil is still discussed. Both, source and maturity estimates from biomarkers, are in favor of atype II/III organic matter source. Likely the oils were formed from the studied black shales (deeper Ngimbang Fm.)which contained a Type III component in the Type II predominated organic matter. In all samples large numbersof active microorganisms were present. Rates for aerobic methane oxidation were high, as was the potential of themicrobial communities to degrade different hydrocarbons. The data suggests a transition of microbial populationsfrom an anaerobic, hydrocarbon-driven metabolism in fresher samples from center or from small seeps to moregeneralistic, aerobic microbial communities in older, more consolidated sediments. Ongoing microbial activity incrater sediment samples under high temperatures (80-95C) indicate a deep origin of the involved microorganisms.First results of molecular analyses of the microbial community compositions confirm the above findings. Thisstudy represents an initial step to better understand onshore seepage systems and provides an ideal analogue forcomparison with the better investigated offshore structures.

Potential sources of hydrocarbons and their microbial degradation in

sediments from the deep geothermal Lusi site, Indonesia

http://oceanrep.geomar.de/43040/1/EGU2017-6423-1.pdf

Potential sources of hydrocarbons and their microbial degradation in sediments from the deep geothermal Lusi site, Indonesia

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