This meeting took place at Burlington House on 14 and 15 June 1989. Until recently a specialist structural geology theme such as this would have been solely the preserve of Tectonic Studies Group. There is, however, currently much encouraging collaboration between industry academia research into all aspects extensional faulting thus was held under joint aegis Petroleum Group The hope that draw participation from fulfilled, with number talks presented overall attendance dividing roughly...

Reactivation involves the accommodation of geologically separable displacement events (intervals >1 Ma) along pre-existing structures. The definition a significant period quiescence is central to this phenomenological and duration interval chosen represents resolution limit reactivation criteria found in most ancient settings. In neotectonic environments, can be further defined as displacements structures that formed prior onset current tectonic regime. This mechanistic cannot always...

Abstract The McKenzie model of continental lithosphere extension describes the first-order responses crustal thinning and geothermal gradient increase following rifting, which lead to syn- post-rift basin subsidence. At sub-basin scale, seismic data show fundamental importance major basement faults in controlling geometry subsidence rifted sedimentary basins. Reflection earthquake seismology that these are generally planar extend down 10–15 km mid-crustal level. Below this depth deformation...

Backstripping is a technique employed to analyse the subsidence history of extensional basins, and involves progressive removal sediment loads, incorporating isostatic decompaction responses this unloading. The results backstripping calculations using 1D models employing local (Airy) isostasy 2D "flexural" are compared for three cross-sections North Sea rift basin. commonly used estimate stretching factor (beta ) across basins. At structural highs Airy will overestimate beta by comparison...

Research Article| June 01, 1986 Caledonian ductile thrusting in a Precambrian metamorphic complex: The Moine of northwestern Scotland DAVID BARR; BARR 1British Geological Survey, 19 Grange Terrace, Edinburgh EH9 2LF, United Kingdom Search for other works by this author on: GSW Google Scholar ROBERT E. HOLDSWORTH; HOLDSWORTH 2Department Sciences, University Liverpool, Brownlow Street, Liverpool L69 3BX, ALAN M. ROBERTS Author and Article Information Publisher: Society America First Online: 01...

It has been recognized for over a decade that large-displacement, pre-Jurassic faults are present in the Northern Viking Graben, part of North Sea rift. These define series major fault-blocks below more obvious Jurassic rift basin. We attempt here to quantify amount extension associated with this older event, which is probably early Triassic age. Quantitative modelling and succeeding period thermal subsidence undertaken, using combination flexural backstripping flexural-cantilever forward...

The magnitude and distribuion of late Jurassic extension in the Northern Viking Graben has been investigated by (i) syn-rift forward modelling using flexural-cantilever model continental rifting; (ii) post-rift flexural backstripping a series cross-sections; (iii) analysis fault-population statistics. Application these three techniques indicates that on tilted fault-block terrains East Shetland Basin, Tampen Spur western Horda Platform is average c. 15% ( β = 1.15). In graben axis regional...

ABSTRACT When removed from their egg membranes, Xenopus embryos can swim. High-speed cinematography shows that, in swimming, lateral undulations pass rostro-caudally down the body. The swimming rhythm period is 40-100 ms. In electrical activity myotomal muscles alternates on opposite sides of a segment and sweeps ipsilateral myotomes. Myotome muscle physiology was examined. Muscle fibres are electrically coupled to each other, able spike. possible role conduction pathway discussed.

Abstract The South Caspian Basin is believed to contain more than 20 km of Mesozoic and Tertiary sediments deposited on oceanic or thinned continental crust. Mesozoic, Palaeogene Oligo-Miocene have not been penetrated within the itself but are exposed onshore in basin margins. Pliocene–Recent sequence has mapped a regionally extensive grid two-dimensional (2D) seismic data by recently drilled exploration wells, over 7 thick. Most this (6 km) formed fluvial–lacustrine deltaic Pliocene...

Aglantha can swim in two ways, one of which, fast swimming, is evoked by contact with predators and serves for escape. The response consists or three violent contractions which the first propels animal a distance equivalent to five body lengths. Peak velocities range 0.3–0.4 m s −1 were measured. Drag reduced contraction tentacles.Coordination escape swimming tentacle achieved system giant axons. A axon runs down each tentacle; action potentials these elements show one-for-one correspondence...

ABSTRACT Intracellular and extracellular recordings from the two large-diameter S T sensory fibres of posterior thoracico-coxal muscle receptor in shore crabs confirm graded, dynamic-static nature potentials evoked by stretching muscle, lack afferent impulses. Slow ramp-function stretches evoke with characteristic shapes, which differ between several respects: The dynamic component fibre resembles an algebraic sum length velocity responses a variable initial ‘acceleration’ (?) transient,...

ABSTRACT Aglantha digitale (Hydrozoa) has a ring giant axon, up to 35 μm in diameter, which runs all round the margin of bell outer nerve-ring. Running from margin, inside towards apex are eight motor axons, 40 diameter. These synapse with sub-umbrellar myoepithelium and therefore motoneurones. The myoepithelial cells line have striated muscular tails running circumferentially. Contraction this circular musculature forces water out propels medusa through water. A large axon (up 7 diameter)...

Abstract The occurrence of failed breakup basins and deepwater blocks thinned continental crust is commonplace in the rifting continents, as part passive margin development. This paper examines Pangaea–Gondwanaland subsequent to form South Atlantic Ocean, with development a basin seafloor spreading axis (the Santos Basin) an adjacent block Sao Paulo Plateau) using combination 2D flexural backstripping gravity inversion modelling. effects varying amounts crustal thinning on contrasting...

The post-Cretaceous subsidence history of the Vøring Basin, part Atlantic passive margin offshore mid-Norway, has been investigated. Extension and β -factors related to rifting continental break-up during Palaeocene have quantified using both forward reverse basin-modelling techniques. In preferred geological model it is assumed that occurred in Basin (prior break-up), following an earlier rift event Late Jurassic. During basin may dynamically uplifted by Iceland mantle plume. east there was...

Abstract The structural evolution of the Viking Graben has been fundamental control on deposition Brent Group and development trapping geometries. Major crustal extension in early Triassic caused tilting basement fault blocks, which can still be clearly seen at basin margins. By mid-Triassic a post-rift thermal-subsidence was established. Local indicates onset second period extension, although main subsidence this time thermal relaxation following rifting. Extension during only c. 1%...

Abstract It has been demonstrated previously that the rigid-domino model of extensional faulting can account well for uplift/subsidence patterns observed within particular areas North Sea rift. This model, however, provides an unsatisfactory solution to deformation occurring at basin margins. is suggested here domino elegant, geometric simplification more complete flexural-isostatic fault displacements. Application a flexural allows unified treatment and its The basin-margins Sea/Mid-Norway...

Abstract The late Jurassic structure of the Central Graben is discussed, both in terms extensional features developed at this time and their subsequent controls on younger inversion structures. regional kinematics North Sea rift suggest that during opened approximately orthogonally to main NNW—SSE fault-trend within basin. Some evidence Triassic faults were reactivated seen towards basin margins, a significant history inferred. comprises axial c. 100 km ( s.l. ). axis offset progressively SE...

The Loch Quoich Line, a major structural line at least 60 km in length, within the Moine of Northern Highlands Scotland, has hitherto been variously interpreted as tectonic dislocation. root zone nappe, and an unconformity. work reported here was carried out type locality line, directed resolving these ambiguities. lithostratigraphic succession established by sedimentary structures shows that rocks Glenfinnan Division are older than, but stratigraphically continuous into, those Eil Division....

The post-rift history of the North Viking Graben has been backstripped in 3D, producing a sequence palaeobathymetric maps that culminates at Late Jurassic synrift stage. backstripping takes into account three main processes which drive basin development: thermal subsidence, flexural-isostatic loading and sediment compaction. Before was performed, Norwegian Trench, bathymetric feature within present-day seabed, smoothed order to remove associated decompaction artefacts results....

Geological relationships in the offshore basins flanking northern Scotland suggest that a regional Caledonian control on structure of these is far from proven, but conversely Mesozoic faults set may extend onshore. The Strathconnon fault, long held to be late Caledonian, age, forming principal kinematic link between east and west coast Scotland. numerous outcrops Precambrian basement within Minch/Hebrides basin nearly all lie uplifted footwalls faults. Similar fault controls distribution...

ABSTRACT In the jellyfish Aglantha digitale escape swimming is mediated by nearly synchronous activity of eight giant motor axons which make direct synaptic contact with contractile myoepithelial cells on under-surface body wall. The delay in transmission at these synapses was 0·7 ± 0·1 ms (± S.D. ;N= 6) 12 °C as measured from intracellular records. Transmission depended presence Ca2+ bathing medium. It not blocked increasing level Mg2+ to 127 mmol 1−1. myoepithelium a thin sheet...