نتایج جستجو برای: magmatic differentiation

تعداد نتایج: 228233  

The Eocene-Oligocene Sarbisheh volcanic complex is a part of the Lut-Sistan Zone that outcrops in eastern Iran. In the east of this complex, three groups of volcanic rocks (i.e., andesite, dacite, and rhyolite) exist. Plagioclase as the main mineral of these rocks is found with varying micro-textures. Based on a changing trend in the concentration of anorthite, the developed micro-textures (coa...

Journal: :Geology 2022

The magmatic stratigraphy of the Sudbury Igneous Complex (Canada) is thought to have resulted from closed-system differentiation an initially homogeneous impact melt sheet. topography its upward-growing chamber floor therefore been planar and subhorizontal. However, we report on discovery a large pothole-like depression (~300 m in depth ~550 width) this complex. has revealed through two-dimensi...

2016
Jonathan P Perkins Kevin M Ward Shanaka L de Silva George Zandt Susan L Beck Noah J Finnegan

The Altiplano-Puna Magma Body (APMB) in the Central Andes is the largest imaged magma reservoir on Earth, and is located within the second highest orogenic plateau on Earth, the Altiplano-Puna. Although the APMB is a first-order geologic feature similar to the Sierra Nevada batholith, its role in the surface uplift history of the Central Andes remains uncertain. Here we show that a long-wavelen...

2012
Massimo Chiaradia Alexey Ulianov Kalin Kouzmanov Bernardo Beate

Porphyry systems supply most copper and significant gold to our economy. Recent studies indicate that they are frequently associated with high Sr/Y magmatic rocks, but the meaning of this association remains elusive. Understanding the association between high Sr/Y magmatic rocks and porphyry-type deposits is essential to develop genetic models that can be used for exploration purposes. Here we ...

1999
FRANCO BIONDI JULIANNA E. FESSENDEN

We conducted dendroclimatic and stable isotope analyses of lodgepole pines (Pinus contorta) located in high-mortality sites at Mammoth Mountain (California, USA) to test for tree responses to magmatic degassing. Existing climatic and tree-ring data from nearby Yellowstone National Park were used for comparison. Sampled trees were scarcely sensitive to climate, and their growth showed an overall...

2016
Chiara Maria Petrone Giuseppe Bugatti Eleonora Braschi Simone Tommasini

Constraining the timescales of pre-eruptive magmatic processes in active volcanic systems is paramount to understand magma chamber dynamics and the triggers for volcanic eruptions. Temporal information of magmatic processes is locked within the chemical zoning profiles of crystals but can be accessed by means of elemental diffusion chronometry. Mineral compositional zoning testifies to the occu...

2007
F. ZEB PAGE T. USHIKUBO N. T. KITA L. R. RICIPUTI J. W. VALLEY

Ion microprobe analysis with a sub-micrometer diameter spot reveals a sharp, 2 μm gradient in oxygen isotope ratio proving that oxygen diffusion in zircon is slow even under prolonged high-grade metamorphism. The data are consistent with an oxygen diffusion coefÞ cient of 10–23.5±1 cm2/s. Furthermore, this gradient is found in a zircon that contains clear textural evidence of recrystallization ...

2010
B. O. Mysen

The viscosities of eight melt compositions in the System albite-H20-F20_1 have been determined at high pressure and temperature. Measurements were performed using the falling sphere method at 1000-1600°C and 2.5 to 22.5 kbar. Fluorine and water strongly decrease the viscosity of albite melt at all pressures and temperatures investigated. The viscosity of a fluorine-bearing albitic melt decrease...

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