Origin of Potassium-rich Silica-deficient Igneous Rocks (eBook)

The book summarizes the occurrence, geochemistry, mineralogy, petrology and phase-equilibria studies in air and under high pressures related to the most intriguing group of potassium-rich mafic and ultramafic rocks, often including host of exotic mineral assemblages including feldspathoids. Mantle-derived K-rich melts had intrigued most of the founders of Geology and many of the later experts in the field of Igneous Petrology, because they are sometimes associated with carbonatites and even diamond. They tend to contain anomalous concentration of many such elements as K, Rb, Sr, U, F, P, etc., along with Ni, Co and Cr indicating a mixture of crust and mantle materials. Although these rocks occur rarely in ancient geologic time, they have been erupting mostly in modern geological history (less than last 120 Ma or so). Are the old age data real or the result of a sampling problem? Modern observations leave no doubt that sediments must be subducted on a large scale. There is now evidence that the upper mantle (and perhaps even the lower mantle) is not homogeneous but rather like a fruit cake, and that there are thermal anomalies in the mantle resulting from deep mantle plumes or subduction. Is this related to release of these unusual rocks clearing the mantle of left over subduction materials? This volume, written for those interested in the geochemistry of K-rich melts from the deep Earth, reviews the present state of knowledge of these unique igneous rocks. The author is an expert in the field of Igneous Petrology and the book will serve as a valuable reference book for researchers and academicians in the discipline.

Dr. Alok K Gupta was born on December 25, 1942. He received his PhD from the University of Pittsburgh (USA), and conducted his post-doctoral studies at the following Universities: Pittsburgh (USA, three years), Western Ontario (Canada, three years), Ruhr (Germany, one year), Hokkaido (Japan, two years), Melbourne and Tasmania Universities (Australia, one year each). He had been Visiting Professors at the Universities of Texas (USA) and Bristol (UK). He had been the Founder Director of the National Centre of Experimental Mineralogy and Petrology and Founder Head of the Department of Earth and Planetary Sciences, University of Allahabad. He is presently an Emeritus Professor and the Raja Ramanna Fellow of the Atomic Energy Commission. Dr. Gupta has received many awards in his distinguished career, such as Career Award (University Grants Commission), Shanti Swaroop Bhatanagar Prize (C.S.I.R), Rhode Memorial Award (Indian Science Congress Association), Best Teacher Award (Allahabad University), Jawaharlal Nehru Birth Centenary Lecture Award of the Indian National Science Academy and Birbal Sahani Gold Medal (Indian Science Congress Association). He is a fellow of all the three National Science Academies of India. He had been Vice-President of both Indian National Science Academy and National Academy of Science (India). He had been an associate editor of the Proceedings Earth and Planetary Sciences (Indian Academy of Sciences) and Managing Editor of the Journal of National Academy Science Letters.

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The book summarizes the occurrence, geochemistry, mineralogy, petrology and phase-equilibria studies in air and under high pressures related to the most intriguing group of potassium-rich mafic and ultramafic rocks, often including host of exotic mineral assemblages including feldspathoids. Mantle-derived K-rich melts had intrigued most of the founders of Geology and many of the later experts in the field of Igneous Petrology, because they are sometimes associated with carbonatites and even diamond. They tend to contain anomalous concentration of many such elements as K, Rb, Sr, U, F, P, etc., along with Ni, Co and Cr indicating a mixture of crust and mantle materials. Although these rocks occur rarely in ancient geologic time, they have been erupting mostly in modern geological history (less than last 120 Ma or so). Are the old age data real or the result of a sampling problem? Modern observations leave no doubt that sediments must be subducted on a large scale. There is now evidence that the upper mantle (and perhaps even the lower mantle) is not homogeneous but rather like a fruit cake, and that there are thermal anomalies in the mantle resulting from deep mantle plumes or subduction. Is this related to release of these unusual rocks clearing the mantle of left over subduction materials? This volume, written for those interested in the geochemistry of K-rich melts from the deep Earth, reviews the present state of knowledge of these unique igneous rocks. The author is an expert in the field of Igneous Petrology and the book will serve as a valuable reference book for researchers and academicians in the discipline.