Recent developments of infrared array cameras in France

We describe three recent infrared cameras, developed in France and based on mosaïcs of infrared detectors. They are optimized for ground-based observations in the 1–5 m or 5–17 m ranges. The results already obtained, emphasize the interest of studying the sky in that domain.Paper presented at the 11th European Regional Astronomical Meetings of the IAU on New Windows to the Universe, held 3–8 July, 1989, Tenerife, Canary Islands, Spain.     

Fracture analysis in the south-western Corinth rift (Greece) and implications on fault hydraulic behavior

This paper reviews the data concerning the fracture network and the hydraulic characteristics of faults in an active zone of the Gulf of Corinth. Pressure gap measured through fault planes shows that in this area the active normal faults (Aigion, Helike) act, at least temporarily and locally, as transversal seal. The analysis of the carbonate cements in the fractures on both the hangingwall and the footwall of the faults also suggests that they have acted as local seals during the whole fault zone evolution. However, the pressure and the characteristics of the water samples measured in the wells indicate that meteoric water circulates from the highest part of the relief to the coast, which means it goes through the fault zones. Field quantitative analysis and core studies from the AIG-10 well have been performed to define both regional and fault-related fracture networks. Then laboratory thin section observations have been done to recognize the different fault rocks characterizing the fault zone components. These two kinds of approach give information on the permeability characteristics of the fault zone. To synthesize the data, a schematic conceptual 3D fluid flow modeling has been performed taking into account fault zone permeability architecture, sedimentation, fluid flow, fault vertical offset and meteoric water influx, as well as compaction water flow. This modeling allows us to fit all the data with a model where the fault segments act as a seal whereas the relays between these segments allow for the regional flow from the Peloponnese topographic highs to the coast.     

Présence d'une mangrove à Avicennia au Miocène moyen dans la région de Digne (Alpes-de-Haute-Provence,France) : implications stratigraphiques et paléoclimatiques

Avicennia pollen grains have been discovered in marine facies from the Middle Miocene deltaic series of Châteauredon (southeastern France). Based on the local stratigraphy, an age between 15.8 and 16.5 Ma is proposed for these grains. The age and the transgressive context of the Avicennia bearing-levels are in agreement with the maximum extension of the mangrove known in the western Mediterranean during interval N8–NN4 pro parte, in relation with the Langhian highstand. This mangrove occurrence at 42°N latitude during Middle Miocene is a more northern witness of the mangrove sites known in Languedoc and Provence areas. It also implies a lower climatic gradient than today. To cite this article: J.-J. Châteauneuf et al., C. R. Geoscience 338 (2006).     

3D geological modelling of the Renard 2 kimberlite pipe,Québec,Canada: from exploration to extraction

The Renard 2 kimberlite pipe is one of nine diamondiferous kimberlite pipes that form a cluster in the south-eastern portion of the Superior Province, Québec, Canada and is presently being extracted at the Renard Mine. It is interpreted as a diatreme-zone kimberlite consisting of two Kimberley-type pyroclastic units and related country rock breccias, all cross-cut by coherent kimberlite dykes and irregular intrusives. Renard 2 has been the subject of numerous diamond drilling campaigns since its discovery in 2001. The first two geological models modelled kimberlite and country rock breccia units separately. A change in modelling philosophy in 2009, which incorporated the emplacement envelope and history, modelled the entire intrusive event and projected the pipe shape to depth allowing for more targeted deep drilling where kimberlite had not yet been discovered. This targeted 2009 drilling resulted in a > 400% increase in the volume of the Indicated Resource. Modelling only the kimberlite units resulted in a significant underestimation of the pipe shape. Current open pit and underground mapping of the pipe shape corresponds well to the final 2015 geological model and contact changes observed are within the expected level of confidence for an Indicated Resource. This study demonstrates that a sound understanding of the geological emplacement is key to developing a reliable 3D geological and resource model that can be used for targeted delineation drilling, feasibility studies and during the initial stages of mining.

     

Spatiotemporal changes in cadmium contamination in the Seine estuary (France)

Cadmium (Cd) is among the major contaminants in the Seine estuary. In the biota, the RNO (Réseau National d’Observation, the French Mussel-Watch) has shown that Cd concentrations in mussels living at the mouth of the estuary are related to changes in inputs to this area of phosphogypsum, a calcium sulphate that is a by-product of the phosphoric acid naturally enriched with Cd. In the water column, Cd concentrations at several key estuary sites show a very marked trend toward decreased contamination in the particles as well as in the dissolved phase. The behavior of Cd in the estuary has been studied between 1991 and 1998 in the framework of the scientific program Seine-Aval. This program has highlighted punctual Cd inputs in the estuarine water column. The partition of Cd between the dissolved and the particulate phase, previously described in various estuaries, is characterized by an intense phenomenon of solubilization in the mixing zone freshwater-seawater, but the colloidal Cd fraction remains low along the whole salinity gradient, about 5% to 10% of the apparent dissolved fraction. Although the decrease of inputs induced a fall of Cd concentrations in the water column, laboratory experiments show that the estuarine particles are far from being exhausted in Cd. Despite continuous efforts to reduce the urban and industrial inputs into the estuarine and coastal waters, the Seine estuary still remains very contaminated by Cd.     

Organic matter quality in reclaimed boreal forest soils following oil sands mining

Following surface mining of the Athabasca Oil Sands deposits in northeastern Alberta, Canada, land reclamation entails the reconstruction of soil-like profiles using salvaged soil materials such as peat and mining by-products. The overall objective of this research was to assess soil organic matter (SOM) quality in different reclamation practices as compared to undisturbed soils found in the region. Soil samples (0–10 cm) were taken from 45 plots selected to represent undisturbed reference ecosites and reclamation treatments. Soil OM pools were isolated using a combination of acid hydrolysis and physical separation techniques. Chemical composition of the low density fractions was characterized using ramped cross polarization (RAMP-CP) ¹³C nuclear magnetic resonance (NMR). Differences between disturbed and undisturbed sites reflected the influence of different botanical inputs (peat vs. forest litter) to SOM composition. Reconstructed soils were characterized by significantly lower alkyl over O-alkyl carbon (ALK/O-ALK) ratios (0.3) than undisturbed sites (0.5). For these reconstructed soils, a significantly higher proportion of soil carbon was present in the sand associated (Heavy sand) pool (49.2 vs. 37.3) and in the acid-unhydrolyzable residue (AUR) fraction (61.3 vs. 54.7). These SOM parameters were significantly related to time since reconstruction, with the AUR (p value = 0.012) and Heavy sand (p value = 0.05) fractions decreasing with time since reconstruction, while the ALK/O-ALK ratio increased (p value = 0.006). These findings suggest that the ALK/O-ALK, AUR, and Heavy sand parameters are suitable indicators for monitoring SOM quality in these reconstructed soils following oil sands mining.     

Instability structures, synsedimentary faults and turbidites, witnesses of a Liassic seismotectonic activity in the Dauphiné Zone (French Alps): A case example in the Lower Pliensbachian at Saint-Michel-en-Beaumont

Instability structures, synsedimentary faults and turbidites have been studied in the Lower Pliensbachian succession of Saint-Michel-en-Beaumont, belonging to the Taillefer block, an ancient half-graben emplaced during the Liassic Tethyan rifting. Geometrical and mechanical analyses demonstrate that the instability structures occurred thanks to movements along spineless synsedimentary normal faults, when the turbiditic and limestone layers were already case-hardened and partly fractured by tension gashes even when the mudstones were still unlithified. Both the tension gashes and the synsedimentary faults are homogeneous in strike with the major regional faults and are in good agreement with the regional direction of extension for this period. The characters of the turbiditic beds, with erosive base, graded bedding, and incomplete Bouma sequence, are in favour of a seismic origin. Instability structures, spineless synsedimentary faults and turbiditic inflows are thus considered as seismites and interpreted as the result of high seismicity periods including some events with M > 5 in the general extensive ambiance of the Liassic Tethyan rifting. The analysis of the geometrical relationships between all these sedimentary features allows to distinguish the successive stage of occurrence of an instability structure, from the sedimentation of alternating marls and limestones, and sudden turbiditic inflows, then early case-hardening of the turbidites, until the important seismotectonic event generating the spineless normal faults, themselves triggering the fall of indurated blocks and locally the forming of breccias. The Ornon Fault, which constitutes the border of the Taillefer block, 15 km eastward, played a major role during the Liassic sedimentation and may represent the major seismic fault related to the seismites occurrence in the Beaumont basin.     

海带(Laminaria japonica)幼孢子体生长和光合作用的N需求

根据室内和围隔实验中海带幼孢子体在不同硝态氮浓度下的生长情况和光合作用速率(Pmax),分析了幼孢子体的N需求,得到其最大生长率(μm)为0.12d-1,维持生存的最低组织N含量(NQ)为16.8μg/mgDW,以最大生长率生长所必需组织N的临界值(NC)为20.4μg/mgDW,每天以最大速率生长的N需求(Nreq)为2.45μg/mgDWd-1。同时,不同处理组的初始NO3-N浓度越高,海带幼孢子体吸收速率和组织N的累加速率越高,且呈明显的线性相关关系(R2分别为0.8393和0.7793,P<0.05)。现场围隔实验中,叶绿素a含量(R2=0.7907,P<0.05)和组织N含量(R2=0.9147,P<0.01)与Pmax也呈明显的线性相关关系。同时,根据海带幼孢子体N的需求和营养吸收状况,分析认为,海带幼孢子体存在受到N限制的风险,但凭其营养吸收能力有适应N限制的能力。还根据海带的这种生理特征,探讨了大型海藻的养殖对富营养化海水的生态调控。