Magma-driven, high-grade metamorphism in the Sveconorwegian Province, southwest Norway, during the terminal stages of Fennoscandian Shield evolution

Recently it has been argued that the Sveconorwegian orogeny in southwest Fennoscandia comprised a series of accretionary events between 1140 and 920 Ma, behind a long-lived, active continental margin characterized by voluminous magmatism and high-grade metamorphism. Voluminous magnesian granitic magmatism is recorded between 1070 and 1010 Ma (Sirdal Magmatic Belt, SMB), with an apparent drop in activity ca. 1010-1000 Ma. Granitic magmatism resumed ca. 1000-990 Ma, but with more ferroan (A type) compositions (hornblende-biotite granites). This ferroan granitic magmatism was continuous until 920 Ma, and included emplacement of an AMCG (anorthosite-mangerite-charnockite-granite) complex (Rogaland Igneous Complex). Mafic rocks with ages corresponding to the spatially associated granites suggest that heat from underplated mafic magma was the main driving force for lower crustal melting and long-lived granitic magmatism. The change from magnesian to ferroan compositions may reflect an increasingly depleted and dehydrated lower crustal source. High-grade metamorphic rocks more than ~20 km away from the Rogaland Igneous Complex yield metamorphic ages of 1070-1015 Ma, corresponding to SMB magmatism, whereas similar rocks closer to the Rogaland Igneous Complex yield ages between 1100 and 920 Ma, with an apparent age peak ca. 1000 Ma. Ti-in-zircon temperatures from these rocks increase from ~760 to 820 °C ca. 970 Ma, well before the inferred emplacement age of the Rogaland Igneous Complex (930 Ma), suggesting that long-lived, high-grade metamorphism was not directly linked to the emplacement of the latter, but rather to the same mafic underplating that was driving lower crustal melting. Structural data suggest that the present-day regional distribution of high- and low-grade rocks reflects late-stage orogenic doming

Rapid temperature-dependent wound closure following adipose fin clipping of Atlantic salmon Salmo salar L.

Three groups of Atlantic salmon were kept at a constant temperature of 4, 10 and 14 °C. The adipose fins were removed; six fish/group were sampled at 11 subsequent time points post-clipping. Samples were prepared for histopathological examination to study the course of re-epithelization. A score sheet was developed to assess the regeneration of epidermal and dermal cell types. Wounds were covered by a thin epidermal layer between 4 and 6 h post-clipping at 10 and 14 °C. In contrast, wound closure was completed between 6 and 12 h in fish held at a constant temperature of 4 °C. By 18 h post-clipping, superficial cells, cuboidal cells, prismatic basal cells and mucous cells were discernible in all temperature groups, rapidly progressing towards normal epidermal structure and thickness. Within the observation period, only minor regeneration was found in the dermal layers. A positive correlation between water temperature and healing rates was established for the epidermis. The rapid wound closure rate, epidermal normalization and the absence of inflammatory reaction signs suggest that adipose fin clipping under anaesthesia constitutes a minimally invasive method that may be used to mark large numbers of salmon presmolts without compromising fish welfare