First evidence of Renlandian (c. 950–940 Ma) orogeny in mainland Scotland:Implications for the status of the Moine Supergroup and circum-North Atlantic correlations

Central problems in the interpretation of the Neoproterozoic geology of the North Atlantic region arise from uncertainties in the ages of, and tectonic drivers for, Tonian orogenic events recorded in eastern Laurentia and northern Baltica. The identification and interpretation of these events is often problematic because most rock units that record Tonian orogenesis were strongly reworked at amphibolite facies during the Ordovician-Silurian Caledonian orogeny. Lu-Hf and Sm-Nd geochronology and metamorphic modelling carried out on large (>1 cm) garnets from the Meadie Pelite in the Moine Nappe of the northern Scottish Caledonides indicate prograde metamorphism between 950 and 940 Ma at pressures of 6–7 kbar and temperatures of 600 °C. This represents the first evidence for c. 950 Ma Tonian (Renlandian) metamorphism in mainland Scotland and significantly extends its geographic extent along the palaeo-Laurentian margin. The Meadie Pelite is believed to be part of the Morar Group within the Moine Supergroup. If this is correct: 1) the Morar Group was deposited between 980 ± 4 Ma (age of the youngest detrital zircon; Peters, 2001, youngest published zircon date is 947 ± 189 (Friend et al., 2003)) and c. 950 Ma (age of regional metamorphism reported here), 2) an orogenic unconformity must separate the Morar Group from the 883 ± 35 Ma (Cawood et al., 2004) Glenfinnan and Loch Eil groups, and 3) the term ‘Moine Supergroup’ may no longer be appropriate. The Morar Group is broadly correlative with similar aged metasedimentary successions in Shetland, East Greenland, Svalbard, Ellesmere Island and northern Baltica. All these successions were deposited after c. 1030 Ma, contain detritus from the Grenville orogen, and were later deformed and metamorphosed at 950–910 Ma during accretionary Renlandian orogenesis along an active plate margin developed around this part of Rodinia

A new stratigraphic framework for the early Neoproterozoic successions of Scotland

The circum-North Atlantic region archives three major late-Mesoproterozoic to Neoproterozoic tectonic episodes, the Grenville-Sveconorwegian and Renlandian orogenies followed by rifting and formation of the Iapetus Ocean, and each is bracketed by sedimentary successions that define three megasequences. In this context, we summarise sedimentological and geochronological data and propose a new stratigraphic framework for the iconic Torridonian-Moine-Dalradian successions and related units in Scotland. The Iona, Sleat, Torridon and Morar groups of the Scottish mainland and Inner Hebrides, and the Westing, Sand Voe and Yell Sound groups in Shetland, form the newly named Wester Ross Supergroup. They were deposited c. 1000–950 Ma within a foreland basin to the Grenville Orogen and, collectively, are in Megasequence 1. Some of these units record Renlandian orogenesis at c. 960-920 Ma. The newly named Loch Ness Supergroup consists of the Glenfinnan, Loch Eil and Badenoch groups of the Scottish mainland, deposited c. 900–870 Ma and are assigned to Megasequence 2. These units record Knoydartian orogenesis c. 820-725 Ma. The regionally extensive Dalradian Supergroup belongs to Megasequence 3; it was deposited c. <725-500 Ma and records the opening of the Iapetus Ocean, ultimately leading to deposition of the passive margin Cambrian-Ordovician Ardvreck and Durness groups.Publisher PDFPeer reviewe

Caledonian and Pre-Caledonian orogenic events in Shetland, Scotland:evidence from garnet Lu-Hf and Sm-Nd geochronology

Garnet Lu-Hf and Sm-Nd ages from the Shetland Caledonides provide evidence of a pollorogenic history as follows: 1) c. 1050 Ma Grenvillian reworking of Neoarchaean basement; 2) c. 910 Ma Renlandian metamorphism of the Westing Group; 3) c. 622-606 Ma metamorphism of the Walls Metamorphic Series but of uncertain significance because the eastern margin of Laurentia is thought to have been in extension at that time; 4) Grampian I ophiolite obduction at c. 491 Ma followed by crustal thickening and metamorphism between c. 485 and c. 466 Ma; 5) Grampian II metamorphism between c. 458 and c. 442 Ma that appears to have been focused in areas here pre-existing foliations ere gentle-inclined and thus may have been relatively easily reworked; 6) Scandian metamorphism at c. 430 Ma, although the paucity of these ages suggests that much of Shetland did not attain temperatures for garnet growth. There is no significant difference in the timing of Caledonian orogenic events either side of the Walls Boundary Fault, although this need not preclude linkage with the Great Glen Fault. However, the incompatibility of Ediacaran events either side of the Walls Boundary Fault may indicate significant lateral displacement and requires further investigation

Genome-wide analysis of BMI in adolescents and young adults reveals additional insight into the effects of genetic loci over the life course

Genetic loci for body mass index (BMI) in adolescence and young adulthood, a period of high risk for weight gain, are understudied, yet may yield important insight into the etiology of obesity and early intervention. To identify novel genetic loci and examine the influence of known loci on BMI during this critical time period in late adolescence and early adulthood, we performed a two-stage meta-analysis using 14 genome-wide association studies in populations of European ancestry with data on BMI between ages 16 and 25 in up to 29 880 individuals. We identified seven independent loci (P < 5.0 × 10−8) near FTO (P = 3.72 × 10−23), TMEM18 (P = 3.24 × 10−17), MC4R (P = 4.41 × 10−17), TNNI3K (P = 4.32 × 10−11), SEC16B (P = 6.24 × 10−9), GNPDA2 (P = 1.11 × 10−8) and POMC (P = 4.94 × 10−8) as well as a potential secondary signal at the POMC locus (rs2118404, P = 2.4 × 10−5 after conditioning on the established single-nucleotide polymorphism at this locus) in adolescents and young adults. To evaluate the impact of the established genetic loci on BMI at these young ages, we examined differences between the effect sizes of 32 published BMI loci in European adult populations (aged 18-90) and those observed in our adolescent and young adult meta-analysis. Four loci (near PRKD1, TNNI3K, SEC16B and CADM2) had larger effects and one locus (near SH2B1) had a smaller effect on BMI during adolescence and young adulthood compared with older adults (P < 0.05). These results suggest that genetic loci for BMI can vary in their effects across the life course, underlying the importance of evaluating BMI at different age

Deploying building simulation to enhance the experimental design of a full-scale empirical validation project

Empirical validation of building simulation results is a complex and time-consuming process. A well-structured and thorough experimental design is therefore a crucial step of the experimental procedure. A full-scale empirical validation study is planned to take place within IEA EBC Annex 71: “Building energy performance assessment based on in situ measurements”. The experimental data are currently being gathered in two experiments being conducted at the Fraunhofer IBP test site at Holzkirchen in Germany. This paper describes the methodology followed during the experimental design of the project. Particular focus is on how Building Performance Simulation (BPS) was used to assist the preparation of the actual experiment, to determine suitable test sequences, magnitudes of heat inputs and temperature variations. A combination of both deterministic and probabilistic simulation (using the method of Morris) is employed to replicate the actual experiment and to assess the sensitivity of the model to uncertain input parameters. A number of experimental errors are identified in the experiment, primarily concerning the magnitude of heat inputs. Moreover, the paper includes a discussion on lessons learned from the simulations and on the reliability, reproducibility and limitations of the suggested experimental design procedure

Identification of mantle peridotite as a possible Iapetan ophiolite sliver in south Shetland, Scottish Caledonides

The Neoproterozoic Dunrossness Spilite Subgroup of south Shetland, Scotland, has been interpreted as a series of komatiitic and mafic lava flows formed in a marginal basin in response to Laurentian continental margin rifting. We show that ultramafic rocks previously identified as komatiites are depleted mantle peridotites that experienced seafloor hydrothermal alteration. The presence of positive Bouguer gravity and aeromagnetic anomalies extending from the Dunrossness Spilite Subgroup northward to the Shetland Ophiolite Complex suggests instead that these rocks may form part of an extensive ophiolite sliver, obducted during Iapetus Ocean closure in a forearc setting