Mud and fluid migration in active mud volcanoes in Azerbaijan

Mud volcanic eruptions in Azerbaijan normally last for less than a few hours, and are characterized by vigorous extrusion of mud breccias, hydrocarbon gases, and waters. Recent fieldwork and mapping on four active mud volcanoes show that dormant period activity ranges from quiet to vigorous flow of mud and fluids. Geochemical analyses of expelled waters show a wide range in solute concentrations, suggesting the existence of a complex plumbing system. The mud and fluids have a deep origin, but are sometimes stored in intermediate-depth mud chambers. A mixing model between deep-seated saline waters and shallow meteoric water is proposed.     

Upper mantle heterogeneities beneath Eastern Europe

P-wave travel-time residuals for seismograph stations in eastern Europe as reported by ISC for the years 1964–1977 were used for constructing a seismic image of upper mantle heterogeneities in the network region. For the depth range 0–100 km, dominant tectonic features like the Pannonian Basin and the Aegean Sea and western Turkey correlate well with pronounced velocity lows which a ppear to extenddown to a 300 km depth. The velocity anomaly patterns in the depth intervals 300–500 km and 500–600 km are broadly similar but quite different from those of shallower depths. The observed seismic heterogeneities are briefly discussed in terms of large-scale tectonic and geophysical (heat-flow) characteristics of eastern Europe.     

Glacial and environmental changes over the last 60 000 years in the Polar Ural Mountains,Arctic Russia,inferred from a high‐resolution lake record and other observations from adjacent areas

Our knowledge about the glaciation history in the Russian Arctic has to a large extent been based on geomorphological mapping supplemented by studies of short stratigraphical sequences found in exposed sections. Here we present new geochronological data from the Polar Ural Mountains along with a high‐resolution sediment record from Bolshoye Shchuchye, the largest and deepest lake in the mountain range. Seismic profiles show that the lake contains a 160‐m‐thick sequence of unconsolidated lacustrine sediments. A well‐dated 24‐m‐long core from the southern end of the lake spans the last 24 cal. ka. From downward extrapolation of sedimentation rates we estimate that sedimentation started about 50–60 ka ago, most likely just after a large glacier had eroded older sediments from the basin. Terrestrial cosmogenic nuclide (TCN) exposure dating (¹⁰Be) of boulders and Optically Stimulated Luminescence (OSL) dating of sediments indicate that this part of the Ural Mountains was last covered by a coherent ice‐field complex during Marine Isotope Stage (MIS) 4. A regrowth of the glaciers took place during a late stage of MIS 3, but the central valleys remained ice free until the present. The presence of small‐ and medium‐sized glaciers during MIS 2 is reflected by a sequence of glacial varves and a high sedimentation rate in the lake basin and likewise from ¹⁰Be dating of glacial boulders. The maximum extent of the mountain glaciers during MIS 2 was attained prior to 24 cal. ka BP. Some small present‐day glaciers, which are now disappearing completely due to climate warming, were only slightly larger during the Last Glacial Maximum (LGM) as compared to AD 1953. A marked decrease in sedimentation rate around 18–17 cal. ka BP indicates that the glaciers then became smaller and probably disappeared altogether around 15–14 cal. ka BP.     

Unit pockmarks associated with Lophelia coral reefs off mid-Norway: more evidence of control by ‘fertilizing’ bottom currents

High-resolution topographic mapping of Norwegian deep-water Lophelia coral reefs and their immediate surrounding seafloor has disclosed striking associations with small (<5?m diameter) ‘unit’ pockmarks. A total of four study areas with Lophelia reefs and unit pockmarks are here described and discussed. At the large Fauna reef, which spans 500?m in length and 100?m in width (25?m in height), there is a field of 184 unit pockmarks occurring on its suspected upstream side. Three other, intermediate-sized Morvin reefs are associated with small fields of unit pockmarks situated upstream of live Lophelia colonies. For two of the latter locations, published data exist for geochemical and microbial analyses of sediment and water samples. Results indicate that these unit pockmarks are sources of light dissolved hydrocarbons for the local water mass, together with nutrient-rich pore waters. It is suggested that the ‘fertilized’ seawater flows with the prevailing bottom current and feeds directly into the live portion of the Lophelia reefs. With an estimated growth rate of ~1?cm per year for the Morvin Lophelia corals, it would take between 1,000 and 2,000?years for the reefs to colonize the closest unit pockmarks, currently occurring 10–20?m from their leading (live) edges.     

Assessing catch shares' effects evidence from Federal United States and associated British Columbian fisheries

What are the effects of transitioning traditionally managed fisheries to incentive-based catch shares fisheries? In a study of all major United States federal catch share fisheries and associated shared stock fisheries in British Columbia, catch shares result in environmental improvements, economic improvements, and a mixture of changes in social performance, relative to the race for fish under traditional management. Environmentally, compliance with total allowable catch increases and discards decrease. Economically, vessel yields rise, total revenues grow, and long-term stock increases are encouraged. Socially, safety increases, some port areas modestly consolidate, needed processing capacity often reduces, and labor markets shift from part time jobs to full time jobs with similar total employment. Newer catch shares address many social concerns through careful design.     

Discovery of prolific natural methane seeps at Gullfaks, northern North Sea

The Gullfaks and Kvitebjørn fields are located on the North Sea Plateau (135 m water depth), and on an ancient beach (135–190 m) deposited during the sea-level lowstand during the Last Glacial Maximum (LGM). There are several continuous seeps of mainly methane gas, where large patches of Beggiatoa bacterial mats occur. The ‘Heincke’ seep area, which is named after the German research vessel Heincke, has been targeted by scientists studying seep-associated processes and microbiology. The Gullfaks area has a long history of shallow gas and seepage. In 1980, well no. 34/10–10 had a blowout from a reservoir located 230 m below seafloor. The active Heincke seep location has no topographic expression, probably because the seabed consists of dense sand and gravel. Extensive bacterial mats (Beggiatoa sp.) are found on the seafloor at this seep site. Organisms such as hermit crabs were seen ingesting pieces of such mat, indicating ‘trophic bypass,’ where carbon derived directly from seeping methane is evidently feeding directly into higher trophic organisms. Ongoing and future research at this seep location in the North Sea can answer some important questions on the environmental impact of natural methane seeps on continental shelves.     

On upper mantle seismic heterogeneities beneath Fennoscandia

Three-dimensional seismic mapping of the upper mantle beneath Fennoscandia (Baltic Shield) using an ACH-type of inversion technique in combination with P-wave travel-time residual observations from the local seismograph network gave the following results. The central parts of the Baltic Shield are characterized by relatively high seismic velocities down to approximately 300 km. Those parts of the shield most affected by the Caledonide orogeny exhibit relatively low velocities particularly in the uppermost 100 km depth interval. The lower part of the upper mantle (300–600 km) does not exhibit pronounced seismic velocity anomalies and in this respect is in contrast to results from similar studies in regions subjected to neotectonic processes like parts of central and southeastern Europe. The seismic anomaly pattern in the presumed thickened lithosphere is in quantitative agreement with similar ones derived from surface wave dispersion analysis and inversion of electrical measurements. The general orientation of these anomalies coincides with that of the glacial uplift.     

Unit-pockmarks and their potential significance for predicting fluid flow

Unit-pockmarks were recognized as more-or-less insignificant features on the seafloor in the early 1980s. However, this investigation, at four different regions in Norwegian waters, suggests they are more significant for seep detection than previously believed. They occur as circular depressions in the seafloor (diameter < 5 m) either as singular features, as strings, or as clusters. One of our main conclusions is that they are widespread and represent the most recent and most active local seep locations. This is based on their areal density distribution, the finding of relatively high hydrocarbon concentrations inside sampled unit-pockmarks and at locations where they are abundant, and on theoretical considerations. When unit-pockmarks occur together with ‘normal-sized’ pockmarks, they often form to the side of the normal-pockmark centre. Our study also suggests that (1) the driving force behind seafloor hydraulic activity, i.e., the formation of unit-pockmarks, normal-pockmarks, and many other fluid flow features, is pockets of buried free gas, and (2) whereas unit-pockmarks likely manifest cyclic pore-water seepage, their larger related, normal-pockmarks, likely manifest periodic or intermittent gas bursts (eruptions), with extended intervening periods of slow, diffusive, and cyclic pore-water seepage. Our findings suggest that seep detection is most efficiently performed by mapping the seafloor with high-resolution bathymetry (at least 1 m × 1 m gridding), and acquiring geochemical samples where the density of unit-pockmarks is locally highest.