The Piquiri Syenite Massif, southernmost Brazil, is part of the post-collisional magmatism related to the Neoproterozoic Brasiliano-Pan-African Orogenic Cycle. The massif is about 12 km in diameter and is composed of syenites, granites, monzonitic rocks and lamprophyres. Diopside-phlogopite, diopside-biotite-augite-calcic-amphibole, are the main ferro-magnesian paragenesis in the syenitic rocks...

S U M M A R Y An assumption of isothermal and static asthenosphere as the normal state of sublithospheric mantle, as commonly employed in studies of terrestrial magmatism, may be physically implausible for a system cooled from above. The growth of an unstable thermal boundary layer at the base of the lithosphere can lead to small-scale convection, so asthenosphere is expected to be usually conv...

Tertiary±Recent magmatism in the Kenya Rift Valley was initiated c. 35Ma, in the northern part of Kenya. Initiation of magmatism then migrated southwards, reaching northern Tanzania by 5±8Ma. This progressionwas accompaniedby a change in the nature of the lithosphere, from rocks of the Panafrican Mozambique mobile belt through reworked craton margin to rigid, Archaean craton. Magma volumes and ...

upstream blankets, drains and cutoff walls are considered as effective measures to reduce seepage, uplift pressure and exit gradient under the foundation of hydraulic structures. to investigate the effectiveness of these measures, individually or in accordance with others, a large number of experiments were carried out on a laboratory model. to extend the investigation for unlimited arrangement...

This paper analyses Late Cenozoic uplift in the Bolivian Andes, using the morphology of well preserved regional paleosurfaces in the Eastern Cordillera that define three axially draining braided river catchments that formed between ∼12 and ∼9 Ma. Rock uplift since the formation of the paleodrainage systems, which has been quantified using four different methods, is 1705±695 m, with a mean erosi...

At large scale, landscapes result from the combination of two major processes: tectonics which generate the main relief through crust uplift, and weather which accounts for erosion. This paper presents the first method in computer graphics that combines uplift and hydraulic erosion to generate visually plausible terrains. Given a user-painted uplift map, we generate a stream graph over the enti...

Magraatism and volcanism exhibit spatial and temporal clustering on a wide range of scales. Using the spatial pair-correlation function, the number of pairs of magmatic orvolcanic events whose separation is between r« Ar and r + « Ar per unit area, we quantify the spatial clustering of raagraatism and volcanism in several data sets. Statistically self-similar clustering characterized by power l...

The frequent formation of large igneous provinces during the opening of the Atlantic Ocean is a surface manifestation of the thermal and chemical state of convecting mantle beneath the supercontinent Pangea. Recent geochemical and geophysical findings from the North Atlantic igneous province all point to the significant role of incomplete mantle mixing in igneous petrogenesis. On the basis of a...

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The world-class Macraes orogenic gold deposit (∼10Moz resource) formed during the late metamorphic uplift of a metasedimentary schist belt in southern New Zealand. Mineralising fluids, metals and metalloids were derived from within the metasedimentary host. Helium and argon extracted from fluid inclusions in sulphide mineral grains (three crush extractions from one sample) have crustal signatur...