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© 2020. The Authors. Bottom trawling grounds have been expanding to deeper areas of the oceans since the mid-XXth century, and mitigating strategies aimed to protect fish stocks, such as temporal trawling closures, have recently been implemented. Here we investigated the biogeochemical properties of sediment from a deep-sea trawling ground in Palamós Canyon (NW Mediterranean) to assess the effects of a 2-months trawling closure in the recovery of sedimentary organic matter. In comparison to untrawled areas, the continuous erosion and sediment mixing in trawling grounds led to coarser reworked sediments impoverished in organic carbon (∼30% loss) and promoted the degradation of labile compounds (52–70% loss). These impacts persisted after the temporal trawling closure, highlighting that this management strategy is insufficient to restore the seafloor. Considering the continuous expansion of bottom trawling grounds, this activity could have significant and irreversible biogeochemical impacts on ocean margins at a global scale, hampering their carbon burial capacity.

The Yellowhead stratabound sulphide mineralisation at the carbonate-hosted Pend Oreille Zn-Pb deposit consists of en-echelon tabular to lensoidal pyrite-sphalerite-rich orebodies characterised by carbonate replacement and open-space filling textures. Re-Os studies of samples from the Yellowhead ore lenses suggest an age of 512 ± 17 Ma for the mineralisation. Combining this age date with the Cambrian-Ordovician fossil record of the host Metaline Formation and detailed textural analysis of the mineralisation, it is concluded that the Yellowhead sulphide mineralisation is largely diagenetic in origin. Such an origin is similar to that of Irish-type deposits worldwide. The presence of Irish-type deposits in the United States portion of the Kootenay arc opens the possibility of discovering similar mineralisation in the Canadian extension of the Kootenay arc., The Yellowhead stratabound sulphide mineralisation at the carbonate-hosted Pend Oreille Zn-Pb deposit consists of en-echelon tabular to lensoidal pyrite-sphalerite-rich orebodies characterised by carbonate replacement and open-space filling textures. Re-Os studies of samples from the Yellowhead ore lenses suggest an age of 512 ± 17 Ma for the mineralisation. Combining this age date with the Cambrian-Ordovician fossil record of the host Metaline Formation and detailed textural analysis of the mineralisation, it is concluded that the Yellowhead sulphide mineralisation is largely diagenetic in origin. Such an origin is similar to that of Irish-type deposits worldwide. The presence of Irish-type deposits in the United States portion of the Kootenay arc opens the possibility of discovering similar mineralisation in the Canadian extension of the Kootenay arc.

A new mineralisation model is proposed for the massive sulphide deposits in the Macmillan Pass (which had been considered to be SEDEX deposits), documenting the mineralogical evolution of layered mineralisation. It is shown that textures previously thought to have formed via depositional processes actually formed by subseafloor replacement of diagenetic barite. Mineral assemblages associated with barite dissolution in the layered mineralisation include barium carbonate phases (witherite, barytocalcite, and norsethite) intergrown with Zn-Pb sulphides, and abundant barium feldspar (celsian, hyalophane) in mudstones surrounding the layered mineralisation. The barium feldspar formed following transport of Ba in low-sulphate fluids on the margins of the subseafloor replacement system, resulting in whole-rock Ba enrichments (up to 5 wt %) in mudstones 15 m below and above the layered mineralisation. Highly radiogenic 87Sr/86Sr values in hydrothermal ankerites correspond with host-rock alteration within the vent complex, whereas the lower 87Sr/86Sr values in the overlying diagenetic barite and barytocalcite give evidence of mixing between a radiogenic fluid (probably a formation water) and Late Devonian seawater. The complex mineralogy and paragenesis of the layered mineralisation are linked to a protracted history of diagenetic and hydrothermal fluid events, all of which took place in and peripheral to a subseafloor replacement hydrothermal system., A new mineralisation model is proposed for the massive sulphide deposits in the Macmillan Pass (which had been considered to be SEDEX deposits), documenting the mineralogical evolution of layered mineralisation. It is shown that textures previously thought to have formed via depositional processes actually formed by subseafloor replacement of diagenetic barite. Mineral assemblages associated with barite dissolution in the layered mineralisation include barium carbonate phases (witherite, barytocalcite, and norsethite) intergrown with Zn-Pb sulphides, and abundant barium feldspar (celsian, hyalophane) in mudstones surrounding the layered mineralisation. The barium feldspar formed following transport of Ba in low-sulphate fluids on the margins of the subseafloor replacement system, resulting in whole-rock Ba enrichments (up to 5 wt %) in mudstones 15 m below and above the layered mineralisation. Highly radiogenic 87Sr/86Sr values in hydrothermal ankerites correspond with host-rock alteration within the vent complex, whereas the lower 87Sr/86Sr values in the overlying diagenetic barite and barytocalcite give evidence of mixing between a radiogenic fluid (probably a formation water) and Late Devonian seawater. The complex mineralogy and paragenesis of the layered mineralisation are linked to a protracted history of diagenetic and hydrothermal fluid events, all of which took place in and peripheral to a subseafloor replacement hydrothermal system.

Sediment-hosted massive sulphide deposits in the Macmillan Pass have been considered type-characteristic examples of the SEDEX deposit model in which barite coprecipitated with base metal sulphides in a redox-stratified water column. An alternative diagenetic model for subseafloor replacement is proposed in which sulphide mineralisation occurred entirely within the subsurface. The introduction of hot (300 degrees C) hydrothermal fluids into the shallow subsurface (less than 1 km depth) resulted in the thermal degradation of organic matter and generated CO2; this promoted barite dissolution, which provided a source of sulphate for thermochemical sulphate reduction and increased the porosity and permeability within the system. The new model was developed after a number of studies that combined high-resolution petrographic and geochemical data from different parts of the deposit. In contrast to the SEDEX model, alteration footprints will be controlled by the mass transfer involved in (barite) replacement reactions rather than hydrothermal venting, and exploration criteria at a district scale should strongly favour highly productive continental margins., Sediment-hosted massive sulphide deposits in the Macmillan Pass have been considered type-characteristic examples of the SEDEX deposit model in which barite coprecipitated with base metal sulphides in a redox-stratified water column. An alternative diagenetic model for subseafloor replacement is proposed in which sulphide mineralisation occurred entirely within the subsurface. The introduction of hot (300 degrees C) hydrothermal fluids into the shallow subsurface (less than 1 km depth) resulted in the thermal degradation of organic matter and generated CO2; this promoted barite dissolution, which provided a source of sulphate for thermochemical sulphate reduction and increased the porosity and permeability within the system. The new model was developed after a number of studies that combined high-resolution petrographic and geochemical data from different parts of the deposit. In contrast to the SEDEX model, alteration footprints will be controlled by the mass transfer involved in (barite) replacement reactions rather than hydrothermal venting, and exploration criteria at a district scale should strongly favour highly productive continental margins.

A major cause of cell death during myocardial ischemia-reperfusion is mitochondrial dysfunction. We previously showed that the reperfusion of an ischemic myocardium was associated with an accumulation of cholesterol into mitochondria and a concomitant strong generation of auto-oxidized oxysterols. The inhibition of mitochondrial accumulation of cholesterol abolished the formation of oxysterols and prevented mitochondrial injury at reperfusion. The aim of this study was to investigate the impact of hypercholesterolemia on sterol and oxysterol accumulation in rat cardiac cytosols and mitochondria and to analyse the effect of the translocator protein ligand 4′-chlorodiazepam on this accumulation and mitochondrial function. Hypercholesterolemic ZDF fa/fa rats or normocholesterolemic lean rats were submitted to 30 min of coronary artery occlusion followed by 15 min reperfusion where cardiac cytosols and mitochondria were isolated. Hypercholesterolemia increased the cellular cardiac concentrations of cholesterol, cholesterol precursors and oxysterols both in cytosol and mitochondria in non-ischemic conditions. It also amplified the accumulation of all these compounds in cardiac cells and the alteration of mitochondrial function with ischemia-reperfusion. Administration of 4′-chlorodiazepam to ZDF fa/fa rats had no effect on the enhancement of sterols and oxysterols observed in the cytosols but inhibited cholesterol transfer to the mitochondria. It also alleviated the mitochondrial accumulation of all the investigated sterols and oxysterols. This was associated with a restoration of oxidative phosphorylation and a prevention of mitochondrial transition pore opening. The inhibition of cholesterol accumulation with TSPO ligands represents an interesting strategy to protect the mitochondria during ischemia-reperfusion in hypercholesterolemic conditions.