Nature of the Moho Transition Zone in the Oman Ophiolite   总被引：5，自引：2，他引：5  

BOUDIER  F.; NICOLAS  A. 《Journal of Petrology》1995,36(3):777-796

The Moho Transition zone of ophiolites is dominantly composedof dunite, with various types of segregations (gabbros, pyroxenites,and chromitites). Representing a level of magmatic exchangebetween asthenospheric mantle and the constructing ocean crust,it records active melt circulation below a spreading ridge axisand offers the opportunity of observing the distribution ofmelt locally percolating and ponding in a deforming porous matrix.In the Oman ophiolite, the Moho Transition Zone has a thicknessvarying from ten to hundreds of meters; its thickness and compositionare related to the geometry of the asthenospheric mantle flow:thick Moho Transition Zones are on top of mantle diapirs characterizedby vertical flow, whereas thin Moho Transition Zones are presentin areas of horizontal mantle flow. A large high-temperatureplastic strain is recorded in thin Moho Transition zones, incontrast to thick ones where the strain is weaker and heterogeneous.Thick Moho Transition Zones display an intense magmatic activityexpressed by diffuse melt impregnations, dikes and sills. Inthese thick zones, we have studied the geometry of the meltcirculation at various scales. We present here the analysisof textures and lattice fabrics which record high-temperatureplastic strain and allow us to quantify it Melt circulates withinthe dunites and can locally destroy the solid framework, inrelation to a viscosity drop and the sharp overturn of mantleflow observed in this type of transition zone. KEY WORDS: Oman; ophiolite; Moho Transition Zone; textures ^*Corresponding author  相似文献   

Deep and High-temperature Hydrothermal Circulation in the Oman Ophiolite--Petrological and Isotopic Evidence   总被引：2，自引：0，他引：2  

BOSCH  D.; JAMAIS  M.; BOUDIER  F.; NICOLAS  A.; DAUTRIA  J.-M.; AGRINIER  P. 《Journal of Petrology》2004,45(6):1181-1208

A systematic search for evidence of high-temperature hydrousalteration within the gabbros of the Samail ophiolite (Oman)shows that most of the gabbros have been affected by successivestages of alteration, starting above 975°C and ending below500°C. Sr and O isotopic analyses provide constraints onthe nature and origin of the fluids associated with these alterationevents. Massive gabbros, dykes and veins and their associatedminerals depart from mid-ocean ridge basalt (MORB)-source magmasignatures (⁸⁷Sr/⁸⁶Sr >0·7032 and depleted  相似文献   

Textural Insights on Significance of Ophiolitic Chromitites,with Special Reference to Oman     

Adolphe NICOLAS  Fran?oise BOUDIER 《《地质学报》英文版》2020,94(Z1):4-4

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