Non-volcanic Rifting Of Continental Margins: A Comparison Of Evidence From Land And Sea (geological Society Special Publication Number 187)

Non-volcanic continental margins may form up to 30% of all present-day passive margins, and remnants of them are preserved in mountain belts. The papers in this volume demonstrate the benefits of integrating offshore and onshore studies, and illustrate the range of information obtained at different scales when comparing evidence from land and sea. Data sets collected across a range of spatial scales are evaluated: thin sections, cores, outcrops, seismic reflection profiles, and other geophysical data. The outcrop scale is crucial because it enables the spatial gulf to be bridged between DSDP and ODP cores and marine seismic data. There is also the problem that basins on land and beneath the sea inevitably have had different post-rift histories resulting in their contrasting present-day elevation. In mountain belts, portions of continental margins and oceanic crust are superbly exposed, but dismembered by subsequent compressional tectonics. Of present-day passive margins, extensional features have only been slightly deformed, if at all, by compressional movements, but are buried beneath significant thicknesses of post-rift sediments and so can only be sampled by ocean drilling at a small number of points. The first paper reviews the synergies that have occurred between investigations of the eastern North Atlantic non-volcanic margins and remnants of similar Mesozoic margins preserved in the Alps, and some later papers return to this theme. However, papers describing margins from other parts of the world show that it may be premature to use models based on the Atlantic and the Alps as the paradigm for all non-volcanic margins. The following 25 papers in the book are grouped under the following headings: (1) Margin overviews; (2) Exhumed crust and mantle; (3) Tectonics and stratigraphy; and (4) Numerical models of extension and magmatism. Readership: Geologists, geophysicists, geochemists, oceanographers, petroleum explorationists. Also available: The Gregory Rift Valley and Neogene-Recent Volcanoes of Northern Tanzania - Memoir no 33 - ISBN 1862392676 Permo-carboniferous Magmatism And Rifting in Europe (Geological Society Special Publication) - ISBN 1862391521 The Geological Society of LondonFounded in 1807, the Geological Society of London is the oldest geological society in the world, and one of the largest publishers in the Earth sciences.The Society publishes a wide range of high-quality peer-reviewed titles for academics and professionals working in the geosciences, and enjoys an enviable international reputation for the quality of its work.The many areas in which we publish in include:-Petroleum geology-Tectonics, structural geology and geodynamics-Stratigraphy, sedimentology and paleontology-Volcanology, magmatic studies and geochemistry-Remote sensing-History of geology-Regional geology guides

An account of the structural evolution and volcanism of the Gregory Rift Valley in northern Tanzania over the past eight million years. The volume includes a history of the discovery of the African rift valleys, and is illustrated with colour photos of some of the unique features of Tanzanian geology.

vol 147/2 Journal of Geological Magazine

This Memoir effectively summarizes the truly remarkable and visually spectacular volcanic province in northern Tanzania toward the southern end of the Gregory Rift or eastern branch of the East African rift system.

.It is an invaluable addition to the geological literature as it provides an authoritative summary of this region, which contains so many unusual, even unique rock types.

The volume is well illustrated with geological maps, photographs, tables of representative chemical analyses of volcanic rocks, as well as figures showing some of the voluminous geochemical data available. Colour photographs of several of the volcanoes and photomicrographs of some of the rocks enhance the volume. In reviewing the geochemistry of the volcanic rocks, Dawson presents persuasive evidence that the bulk of the magmas, whether basaltic or carbonatitic, originate from the upper mantle, and that any assimilation of continental crustal material is minor or absent.

The author is to be congratulated in giving the geological community a very useful reference guide to this intriguing region and its volcanism.

widespread Extension Occurred Within The Variscan Orogen And Its Northern Foreland During Late Carboniferous To Early Permian Times. This Was Associated With Magmatism And With A Fundamental Change, At The Westphalian-stephanian Boundary, In The Regional Stress Field, Coincident With The Termination Of Orogenic Activity And Onset Of Dextral Translation Between North Africa And Europe. Rifting Propagated Across Basement Terranes With Different Ages And Thermal Histories. Most Of The Rift Basins Developed On Relatively Thin Lithosphere; However, The Highly Magmatic Oslo Graben Initiated Within The Edge Of A Craton. Early Stephanian Regional Uplift Is Contemporaneous With The Onset Of Magmatism, Inviting Speculation That It Might Have Been Induced By A Thermal Anomaly Within The Upper Mantle. The Contributions To This Volume Suggest That The Geodynamic Setting In Which Magmatism Occurred Was Complex, Involving Wrench Tectonics, Slab Detachment, And Delamination Or Thermal Erosion Of The Base Of The Lithosphere.