Physicists attempt to reduce natural phenomena to their essential dimensions by means of simplification and approximation and to account for them by defining natural laws. Paradoxically, whilst there is a critical need in geology to reduce the overwhelming field information to its essentials, it often re- mains in an over-descriptive state. This prudent attitude of geologists is dictated by the nature of the subjects being consi- dered, as it is often difficult to derive the significant parame- ters from the raw data. It also follows from the way that geolo- gical work is carried out....

This volume follows a Specialized Symposium on "Mantle denudation in slow spreading ridges and in ophiolites," held at the XII EUG Meeting in Strasbourg, spring 1993. During the meeting it was felt that the contribu tions to the Symposium justified a volume presenting its main scientific achievements. The present title of the volume shows that the center of inter est has slightly shifted with respect to the initial objective: in order to under stand the processes involved in accretion taking place at oceanic ridges, it is crucial to study the interaction between uppermost mantle and lower...

Teile der Kontinente enthalten trotz mehrfacher Umgestaltung durch die Plattentektonik noch Informationen uber das initiale Stadium der Abkuhlung des Planeten Erde. Im Gegensatz dazu ist in den Ozeanplatten die Geodynamik der Erde aufgezeichnet, wie sie sich in dem geologisch kurzen Zeitraum von 150 MA zwischen ihrem Entstehen an den mittelozeanischen Rucken bis zur Verschluckung in Subduktionszonen abspielt. Beim Studium der ozeanischen Rucken untersucht man den Antriebsmechanismus der geodynamischen Prozesse, die in der Erde ablaufen. Die Besonderheit dieses Buches liegt in der...

Ophiolites are distinctive assemblages of malic to ultramalic rocks representing fragments of the oceanic lithosphere. Nicolas (tectonophysics, U. of Montpelier) establishes a global comparison between ophiolites and their various oceanic environments, to aid in understanding the physical processes

This book is completely in phase with the 1994 science.

1.1. HISTORICAL DEVELOPMENT OF THE OPHIOLITE CONCEPT. Ophiolite, Greek for 'the snake stone', appears to have received its first written definition by Brongniart (1813) as a serpentine matrix containing various minerals. Later in 1821 and 1827, Brongniart determined that volcanic and gabbroic rocks were also present, associated with cherts, and he ascribed an igneous origin to the ophiolite. Amstutz (1980) gives an excellent exegesis of these early contributions and traces the further use of the term and concept of ophiolite. This concept had been forged in the western Alps and Apennines...