Gas emissions and active tectonics within the submerged section of the North Anatolian Fault zone in the Sea of Marmara

The submerged section of the North Anatolian fault within the Marmara Sea was investigated using acoustic techniques and submersible dives. Most gas emissions in the water column were found near the surface expression of known active faults. Gas emissions are unevenly distributed. The linear fault segment crossing the Central High and forming a seismic gap – as it has not ruptured since 1766, based on historical seismicity, exhibits relatively less gas emissions than the adjacent segments. In the eastern Sea of Marmara, active gas emissions are also found above a buried transtensional fault zone, which displayed micro-seismic activity after the 1999 events. Remarkably, this zone of gas emission extends westward all along the southern edge of Cinarcik basin, well beyond the zone where 1999 aftershocks were observed. The long term monitoring of gas seeps could hence be highly valuable for the understanding of the evolution of the fluid-fault coupling processes during the earthquake cycle within the Marmara Sea

Persistent Cell-Autonomous Circadian Oscillations in Fibroblasts Revealed by Six-Week Single-Cell Imaging of PER2::LUC Bioluminescence

Biological oscillators naturally exhibit stochastic fluctuations in period and amplitude due to the random nature of molecular reactions. Accurately measuring the precision of noisy oscillators and the heterogeneity in period and strength of rhythmicity across a population of cells requires single-cell recordings of sufficient length to fully represent the variability of oscillations. We found persistent, independent circadian oscillations of clock gene expression in 6-week-long bioluminescence recordings of 80 primary fibroblast cells dissociated from PER2::LUC mice and kept in vitro for 6 months. Due to the stochastic nature of rhythmicity, the proportion of cells appearing rhythmic increases with the length of interval examined, with 100% of cells found to be rhythmic when using 3-week windows. Mean period and amplitude are remarkably stable throughout the 6-week recordings, with precision improving over time. For individual cells, precision of period and amplitude are correlated with cell size and rhythm amplitude, but not with period, and period exhibits much less cycle-to-cycle variability (CV 7.3%) than does amplitude (CV 37%). The time series are long enough to distinguish stochastic fluctuations within each cell from differences among cells, and we conclude that the cells do exhibit significant heterogeneity in period and strength of rhythmicity, which we measure using a novel statistical metric. Furthermore, stochastic modeling suggests that these single-cell clocks operate near a Hopf bifurcation, such that intrinsic noise enhances the oscillations by minimizing period variability and sustaining amplitude

Carbon isotopic composition of dissolved CO2, CO2 gas and methane in sediments from ODP Leg 172 sites

Carbon isotopic data of interstitial dissolved CO2 (CO2), CO2 gas, and methane show that a variety of microbial diagenetic processes produce the observed isotopic trends. Anaerobic methane oxidation (AMO) is an important process near the sulfate-methane interface (SMI) that strongly influences the isotopic composition of CO2 in the sulfate reduction and upper methanogenic zones, which in turn impacts methane isotopic composition. Dissolved CO2 and methane are maximally depleted in 13C near the SMI, where 13C values are as light as -31.8 and -101 PDB for CO2 and methane, respectively. CO2 reduction links the CO2 and methane pools in the methanogenic zone so that the carbon isotopic composition of both pools evolves in concert, generally showing increasing enrichments of 13C with increasing depth. These isotopic trends mirror those within other methane-rich continental rise sediments worldwide

The importance of multi-parametric analysis in long- term submarine gas emission monitoring: the SN4 ob- servatory at the North Anatolian Fault (Marmara Sea, Turkey)

Methane-rich fluid vents have been widely observed and associated to active faults in the Sea of Marmara, along the submerged portion of the North Ana- tolian Fault (NAF). Episodic gas seepage also occurs in the Izmit Gulf, along the NAF segment that ruptured during the 1999 Izmit earthquake. This site is thus a unique area to test the hypothesis on the relation between strike-slip deforma- tion, seismic activity and gas expulsion within an active fault zone. A long-term multi-parametric experiment can be an effective way to study the irregular dy- namics of gas emission from seafloor and to understand its possible relation with seismic activity. A benthic seafloor observatory (SN-4) was deployed in the Izmit Gulf in 2009 using the R/V Urania as a demonstration mission in the framework of the EC ES- ONET (European Seas Observatory NETwork) project. Instrumental redundancy and specific cross-correlation of data from different sensors, proves to be funda- mental to distinguish actual seepage events from other signals related to ocean- ographic behaviour or even sensor biases. The observatory was equipped with a three component broad-band seismometer, a CTD with turbidity meter, two methane detectors, an oxygen sensor and a current-meter. All sensors installed on the observatory were managed by dedicated low-power electronics, which can manage a wide set of data streams with quite different sampling rates. A unique reference time, set by a central high-precision clock, is used to tag each datum. After six months of continuous monitoring, SN-4 was recovered in March 2010 in order to download the data and replace the batteries for a further six month mission period and finally recovered in October 2010. The data analysis clearly shows frequent degassing events, recorded as methane anomalies in seawater and as high-frequency short-duration signals recorded by the seismometer.. The time series of other oceanographic parameters (tempera- ture, oxygen concentration, turbidity and salinity) shows patterns that seem to be linked to both local gas seepage and to the circulation of water masses in the Gulf of Izmit. A comparative analysis of the various observables and their mutual correlation, can be a key tool to understand actual degassing events along the NAF. This analysis is first attempt in finding possible correlations bePublishedCadiz, Spain3A. Ambiente Marinorestricte

Paratethyan - Mediterranean connectivity in the Sea of Marmara region (NW Turkey) during the Messinian

Geodynamics geophysics and tectonics