Dynamic Surface of the Earth
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Geophysical Abstracts 156-159 January-December 1954
Geophysical Abstracts 156-159 January-December 1954 GEOLOGICAL SURVEY BULLETIN 1022 Abstracts of current literature pertaining to the physics of the solid earth and geophysicq,l exploration UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1955 UNITED STATESlDEPARTMENT OF THE INTERIOR Douglas McKay, Secretary GEOLOGICAL SURVEY W. ~· Wrather, Director CONTENTS [The letters in parentheses are those used to designate the chapters for separate publication] Page (A) Geophysical Abstracts 156, January-March------------------------ 1 (B) Geophysical Abstracts 157, April-June---------------------------- 71 (C) Geophysical Abstracts 158, July-September________________________ 135 (D) Geophysical Abstracts 159, October-December_____________________ 205 Under department orders, Geophysical Abstracts have been published at different times by the Bureau of Mines or the Geological Survey as noted below: 1-86, May 1929-June· 1936, Bureau of Mines Information Circulars. [Mimeo- graphed] 87, July-December 1936, Geological Survey Bulletin 887. 88-91, January-December 1937, Geological Survey Bulletin 895. 92-95, January-December 1938, Geological Survey Bulletin 909. 96-99, January-December 1939, Geological Survey Bulletin 915. 100-103, January-December 1940, Geological Survey Bulletin 925. 104-107, January-December 1941, Geological Survey Bulletin 932. 108-111, January-December 1942, Geological Survey Bulletin 939. 112-127, January 1943-December 1946, Bureau of Mines Information Circulars. [Mimeographed] 128-131, January-December 1947, Geological Survey Bulletin 957. 132-135, January-December 1948, Geological Survey Bulletin 959. 136-139, January-December 1949, Geological Survey Bulletin 966. 140-143, January-December 1950, Geological Survey Bulletin 976. 144-147, January-December 1951, Geological Survey Bulletin 981. 148-151, January-December 1952, Geological Survey Bulletin 991. 152-155, January-December 1953, Geological Survey Bulletin 1002. -
Experimental Early Crystallization of K-Feldspar in Granitic Systems. Implications on the Origin of Magmatic Fabrics in Granitic Rocks
Geologica Acta, Vol.15, Nº 4, December 2017, 261-281 DOI: 10.1344/GeologicaActa2017.15.4.2 J. Díaz-Alvarado, 2017 CC BY-SA Experimental early crystallization of K-feldspar in granitic systems. Implications on the origin of magmatic fabrics in granitic rocks J. DÍAZ-ALVARADO1 1Departamento de Geología. Universidad de Atacama Copayapu 485, Copiapó, Chile. E-mail: [email protected] ABS TRACT One of the most outstanding characteristics of some granodioritic to granitic rocks is the presence of K-feldspar megacrysts. For instance, granodiorites and monzogranites of the Spanish Central System batholith present variable amounts of large (up to 10cm in length) euhedral K-feldspar crystals. The porphyritic textures, the euhedral shape, the alignment of plagioclase and biotite inclusions and the magmatic fabrics point to a magmatic origin for these megacrysts. This work presents a phase equilibria study in a high-K2O granodioritic system. A series of experiments were conducted with a granodioritic composition (GEMbiot) to study the crystallization sequence at the emplacement conditions in the Gredos massif, i.e. 4 H2O wt.% and 0.4GPa. Experimental results show that orthopiroxene is the liquidus phase at 1010ºC, which reacts with the H2O-rich melt to stabilize biotite between 980 and 940ºC. Plagioclase crystallizes at around 910ºC, and K-feldspar crystallizes in the matrix between 750 and 700ºC when the crystal fraction is around 0.5. However, at 850ºC, a pelite-doped experiment shows euhedral K-feldspar (≈5vol%) in both the reactive xenolith domain together with cordierite and the granodioritic domain, where the K2O wt.% rose from 4.5 in the normal experiment to 5.9 in the doped experiment. -
Epidote-Bearing Calc-Alkalic Granitoids in Northeast Brazil
Revista Brasileira de Geociências 20(1-4): 88-100, março/dezembro de 1990 EPIDOTE-BEARING CALC-ALKALIC GRANITOIDS IN NORTHEAST BRAZIL ALCIDES NÓBREGA SIAL* RESUMO GRANITÓIDES COM EPÍDOTO MAGMÁTICO NO NORDESTE DO BRASIL. Um grande número de granitóides cálcio-alcalinos com epidoto são encontrados no Domínio Estrutural Central (DEC) - que compreende três segmentos: Seridó, Cachoeirinha-Salgueiro e Riacho do Pontal - e em algu- mas outras localidades no Nordeste do Brasil. No cinturão Cachoerinha-Salgueiro (CCS), granodioritos e tonalitos com epidoto, meta a peraluminosos, intrudiram fllitos há cerca de 620 Ma, enquanto no Seridó, uma maior variedade de plutões com epfdoto fgneo intrudiu gnaisses Jucurutu ou xistos Seridó. Granodio- ritos com duas micas com (±) granada e epfdoto ígneo (?) intrudiram metassedimentos do Cinturão Riacho do Pontal. Epídoto magmático está também presente nos plutões trondhjemítícos e shoshonítícos - que in- trudiram, respectivamente, xistos Salgueiro e rochas de embasamento ao longo do limite sul do CCS - bem como em plutões no Complexo Surubim-Caroalina e nos cinturões Pajed-Paraíba e Sergipano. E encontra- do em quatro relações texturais, duas das quais indiscutivelmente magmáticas, e duas outras de reações sub- solidus. No CCS, granitóides com epfdoto solidificaram-se geralmente em torno de 6 kbar - 7 kbar, de acor- do com seus teores de Al na homblenda. Pressões mais baixas obtidas para encraves quartzo - dioríticos são devidas à perda de Al através de reação subsolidus com plagioclásio, produzindo epídoto granular. Diferem de granitóides mesozóicos similares na América do Norte porque, embora suas pressões de solidificação se- jam altas, eles intrudiram tanto metassedimentos da fácies xistos verdes como plutões paleozóicos na Argen- tina (Cadeias Pampeanas), Nova Inglaterra (área de Sherbrooke-Lewiston) e Nova Zelândia (Cadeia de Vi- tória). -
Constitution of the Earth's Interior
Component-I (A) - Personal Details Role Name Affiliation Principal Investigator Prof. Masood Ahsan Siddiqui Department of Geography ,Jamia Millia Islamia, New Delhi Paper Coordinator, if any Dr. Sayed Zaheen Alam, Dayal Singh Singh College, Delhi University Content Writer/Author (CW) Dr.Ramashray Prasad DrBhim Rao Ambedkar Associate Professor College (University of Delhi) Yamuna Vihar, Delhi Content Reviewer (CR) Dr. Sayed Zaheen Alam, Dayal Singh Singh College, Delhi University Language Editor (LE) Component-I (B) - Description of Module Items Description of Module Subject Name Geography Paper Name Geomorphology Module Name/Title CONSTITUTION OF THE EARTH’S INTERIOR Module Id GEO/13 Pre-requisites Objectives Keywords SIAl, SIMA, NIFE, Volcanicity, Seismology Introduction Learning Objectives Meaning of Composition and Structure Studying the Earth’s Interior a. Artificial Sources and b. Natural Sources a. Artificial Sources: Density Pressure and Temperature Density Pressure Temperature Relationships of Density, Pressure and Temperature with Depths in the Interior b. Natural Sources Volcanism and Seismology. Volcanicity Seismology Primary, Secondary and Surface waves Characteristics of Primary (P) waves: Characteristics of Secondary (S) waves: Characteristics of Surface (L) waves: Interpretation of Propagating Different Waves Seismology and Constitution of the Earth’s Interior Chemical Composition of the Earth SIAL: SIMA: NIFE Earth’s Internal Structure Crust Mantle Core Conclusions Multiple Choice Questions Answers of MCQs References Web Links ================== CONSTITUTION OF THE EARTH’S INTERIOR Introduction The interior of the earth is that portion which is, possibly, not reachable for us. The parts, from where the sample is not supposed to be taken in our hands, are difficult to understand very well directly. -
The Nature of Lunar Isostasy
45th Lunar and Planetary Science Conference (2014) 1630.pdf THE NATURE OF LUNAR ISOSTASY. Michael M. Sori1 and Maria T. Zuber1. 1Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA ([email protected]). Introduction: One way planetary topography can A key assumption in investigating the role of Pratt be supported is isostatic compensation, in which isostasy by looking at the relationship between crustal overburden pressure of rock is balanced at some depth. density and topography is that the density one observes The regions of the Moon that are not associated with near the surface is representative of the underlying maria or basins are generally isostatically compensated crustal column. We justify that assumption here by [1], an observation that was made when the first noting that calculation of the effective density of the detailed lunar gravity maps were constructed [2] and lunar crust as a function of spherical harmonic degree has held with each subsequently more precise data set considered results in a linear trend [14], supporting the [e.g., 3]. notion of a single-layer crust. There are two models of isostasy commonly Results: We make scatter plots of crustal density considered. In the Airy isostasy model [4], crustal as a function of elevation. One such scatter plot, for thickness is varied such that overburden pressures are the South Pole-Aitken basin, is shown in Figure 1. equal at some depth of compensation. The crust is a Points are sampled in a grid every ~8 km. For each layer of uniform density overlaying a mantle of higher scatter plot, we make a least-squared fit to the data and uniform density. -
Reading Notes on KKV Ch 2: the Interior of the Earth 2.1 EQ
Reading notes on KKV Ch 2: The interior of the earth 2.1 EQ SEISMOLOGY seismic waves, their speed double couple model and focal mechanisms. elastic rebound theory --EXPLAIN how the fault plane and auxiliary plane are different than a fault plane and its conjugate seismic tomography - like medical xrays - an energy source, illuminates the volume, and detected on the other side. in medical you know the energy and the distance travelled - all delays and attenuation of energy arrival at the detector can be attributed to complex paths and rigidity of materials. in earth, beat down the uncertainties by using more and more earthquakes and more and more stations. tomography techniques typically use one type of wave at a time. For body waves (p and s) use travel time, better for deeper imaging of velocity structure. surface waves can be better for picking up anisotropy and shorter wavelength changes. Iterative - between velocity structure and raypath. this process improves earthquake location and magnitude estimation. 2.2 VELOCITY STRUCTURE OF THE EARTH Moho was discovered in 1909. Key observation was that at 200 km from epicenter, p-wave arrivals were before predicted because the crustal paths were at 5.6 km/s and the mantle speed was 7.9 km/s. calculated depth was 54 km. same pattern is found globally - strong velocity contrast from 5.5-6 to 8 km/s at depths of 20 (new cont or rift) -80 (Himalaya) km. mean 40 km. Made my own diagram - purple is direct wave. red is a path to a station near the epicenter pink is a path to a station farther from epicenter. -
Glacial Isostatic Adjustment and Sea-Level Change – State of the Art Report Technical Report TR-09-11
Glacial isostatic adjustment and sea-level change – State of the art report Glacial isostatic adjustment and sea-level change Technical Report TR-09-11 Glacial isostatic adjustment and sea-level change State of the art report Pippa Whitehouse, Durham University April 2009 Svensk Kärnbränslehantering AB Swedish Nuclear Fuel and Waste Management Co Box 250, SE-101 24 Stockholm Phone +46 8 459 84 00 TR-09-11 ISSN 1404-0344 CM Gruppen AB, Bromma, 2009 Tänd ett lager: P, R eller TR. Glacial isostatic adjustment and sea-level change State of the art report Pippa Whitehouse, Durham University April 2009 This report concerns a study which was conducted for SKB. The conclusions and viewpoints presented in the report are those of the author and do not necessarily coincide with those of the client. A pdf version of this document can be downloaded from www.skb.se. Preface This document contains information on the process of glacial isostatic adjustment (GIA) and how this affects sea-level and shore-line displacement, and the methods which are employed by researchers to study and understand these processes. The information will be used in e.g. the report “Climate and climate-related issues for the safety assessment SR-Site”. Stockholm, April 2009 Jens-Ove Näslund Person in charge of the SKB climate programme Contents 1 Introduction 7 1.1 Structure and purpose of this report 7 1.2 A brief introduction to GIA 7 1.2.1 Overview/general description 7 1.2.2 Governing factors 8 1.2.3 Observations of glacial isostatic adjustment 9 1.2.4 Time scales 9 2 Glacial -
A Preserved Early Ediacaran Magmatic Arc at the Northernmost
DOI: 10.1590/2317-4889201620160004 ARTICLE A preserved early Ediacaran magmatic arc at the northernmost portion of the Transversal Zone central subprovince of the Borborema Province, Northeastern South America Arco magmático eoediacarano na porção setentrional da Zona Transversal, sub-província central da Província Borborema, nordeste da América do Sul Benjamim Bley de Brito Neves1*, Edilton José dos Santos2, Reinhardt Adolfo Fuck3, Lauro César Montefalco Lira Santos4 ABSTRACT: Magmatic arcs are an essential part of crust-forming events RESUMO: O objetivo deste trabalho é introduzir o conceito de um in planet Earth evolution. The aim of this work was to describe an early arco magmático eoediacarano (ca. 635–580 Ma) na porção norte da Ediacaran magmatic arc (ca. 635-580 Ma) exposed in the northernmost zona transversal, subprovíncia central da Província Borborema. Nossas portion of the Transversal Zone, central subprovince of Borborema Pro- pesquisas foram beneficiadas pela preexistência de sínteses de diferentes vince, northeast Brazil. Our research took advantage of several syntheses by autores, incluindo teses e dissertações, sobre a zona transversal nos úl- different authors, including theses and dissertations, carried out on mag- timos 30 anos. O arco proposto está situado entre 35º15’W e 42º30’W matic rocks of the study area for the last 30 years. The ca. 750 km long and (extensão ca. 750 km) e 7º15’S e 8ºS (largura de até 140 km), segundo up to 140 km wide arc, trending ENE-WSW, is preserved to the south of trend geral NNE-SSW, ao sul do Lineamento Patos. Cerca de 90 stocks the Patos Lineament, between 35º15’ and 42º30’W and 7º15’ and 8ºS. -
Isostasy and Flexure of the Lithosphere
Isostasy and Flexure of the Lithosphere A. B. WATTS Department of Earth Sciences, Oxford University Oxford, United Kingdom PUBLISHED BY THE PRESS SYNDICATE OF THE UNIVERSITY OF CAMBRIDGE The Pitt Building, Trumpington Street, Cambridge, United Kingdom CAMBRIDGE UNIVERSITY PRESS The Edinburgh Building, Cambridge, United Kingdom http://www.cup.cam.ac.uk 40 West 20th Street, New York, NY 10011–4211, USA http://www.cup.org 10 Stamford Road, Oakleigh, Melbourne 3166, Australia Ruiz de Alarco´ n 13, 28014 Madrid, Spain # Cambridge University Press 2001 This book is in copyright. Subject to statutory exception and to the provisions of relevant collective licensing agreements, no reproduction of any part may take place without the written permission of Cambridge University Press. First published 2001 Printed in the United States of America Typeface Times Ten PS 10/12.5 System 3B2 [KW] A catalogue record for this book is available from the British Library Library of Congress Cataloging-in-Publication Data Watts, A. B. (Anthony Brian), 1945– Isostasy and flexure of the lithosphere / A. B. Watts. p. cm. Includes bibliographical references and index. ISBN 0-521-62272 – ISBN 0-521-00600-7 (pb) 1. Isostasy. 2. Earth – Crust. I. Title. QE511.W38 2001 551 – dc21 00-065146 ISBN 0 521 62272 7 hardback ISBN 0 521 00600 7 paperback Contents Preface page xi Acknowledgments xiii Notation xvii 1 The Development of the Concept of Isostasy 1 1.1 Introduction 1 1.2 First Isostatic Ideas 2 1.3 The Deflection of the Vertical in India 9 1.4 Isostasy According to Airy -
Plate Tectonics
Plate tectonics tive motion determines the type of boundary; convergent, divergent, or transform. Earthquakes, volcanic activity, mountain-building, and oceanic trench formation occur along these plate boundaries. The lateral relative move- ment of the plates typically varies from zero to 100 mm annually.[2] Tectonic plates are composed of oceanic lithosphere and thicker continental lithosphere, each topped by its own kind of crust. Along convergent boundaries, subduction carries plates into the mantle; the material lost is roughly balanced by the formation of new (oceanic) crust along divergent margins by seafloor spreading. In this way, the total surface of the globe remains the same. This predic- The tectonic plates of the world were mapped in the second half of the 20th century. tion of plate tectonics is also referred to as the conveyor belt principle. Earlier theories (that still have some sup- porters) propose gradual shrinking (contraction) or grad- ual expansion of the globe.[3] Tectonic plates are able to move because the Earth’s lithosphere has greater strength than the underlying asthenosphere. Lateral density variations in the mantle result in convection. Plate movement is thought to be driven by a combination of the motion of the seafloor away from the spreading ridge (due to variations in topog- raphy and density of the crust, which result in differences in gravitational forces) and drag, with downward suction, at the subduction zones. Another explanation lies in the different forces generated by the rotation of the globe and the tidal forces of the Sun and Moon. The relative im- portance of each of these factors and their relationship to each other is unclear, and still the subject of much debate. -
STRUCTURE of the EARTH Module-2/3
STRUCTURE OF THE EARTH Module-2/3 On the basis of data assembled from studies of the travel habits of earthquake waves the earth has been divided into three major zones. (i) Crust (ii) Mantle (iii) Core The Crust The outermost thin layer of the lithosphere is crust. Its thickness varies from 16 to 40 km.The crust contain the continental landmass and the ocean basins. In the continental areas, crust is about 40 km thick and in the ocean basin, the thickness of the crust is 5 to 10km.From seismic waves it seems that the surface layer of the continent is composed mainly of granite rocks with specific gravity 2.65 where the seismic velocity is 6km/sec.Because these rocks contain a large proportion of silica and aluminum they are collectively called SIAL. The basement layer is continuous which is exposed on the ocean floor or the ocean basin. The specific gravity is 3.0 and the earthquake waves travel at a speed of 6.7km/sec. The rocks contain silica and minerals rich in magnesium and iron. This layer of basic rocks is termed as SIMA. The Mantle Below the earth’s crust is the second zone, themantle, having mean density of 4.6 gcm-3extends to a depth of approximately 2900km, into the interior of the earth. The line of function between the earth crust and the mantle is called Moho discontinuity after the scientist Mohorovicic who discovered it in 1909.Moho discontinuity lying at a depth of up to 40kms beneath the continents and 6-10 km beneath the ocean floor. -
Geology of Saipan Mariana Islands Part 2
Geology of Saipan Mariana Islands Part 2. Petrology and Soils GEOLOGICAL SURVEY PROFESSIONAL PAPER 280-B-D Geology of Saipan Mariana Islands Part 2. Petrology and Soils GEOLOGICAL SURVEY PROFESSIONAL PAPER 280-B-D Chapter B. Petrology of the Volcanic Rocks By ROBERT GEORGE SCHMIDT Chapter C. Petrography of the Limestones By J. HARLAN JOHNSON Chapter D. Soils By RALPH J. McCRACKEN UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1957 UNITED STATES DEPARTMENT OF THE INTERIOR Fred A. Seaton, Secretary GEOLOGICAL SURVEY Thomas B. Nolan, Director For sale by the Superintendent of Documents, U. S. Government Printing Office Washington 25, D. C. CONTENTS OF PART 2 Page Chapter B. Petrology of the Volcanic Rocks .... 127 Chapter C. Petrography of the Limestones ...... 177 Chapter D. Soils ................................ 189 m GEOLOGICAL SURVEY PROFESSIONAL PAPER 280 Geology of Saipan, Mariana Islands Part 1. General Geology Chapter A. General Geology By PRESTON E. CLOUD, JR., ROBERT GEORGE SCHMIDT, and HAROLD W. BURKE Part 2. Petrology and Soils Chapter B. Petrology of the Volcanic Rocks By ROBERT GEORGE SCHMIDT Chapter C. Petrography of the Limestones By J. HARLAN JOHNSON Chapter D. Soils By RALPH J. McCRACKEN Part 3. Paleontology Chapter E. Calcareous Algae By J. HARLAN JOHNSON Chapter F. Discoaster and Some Related Microfossils By M. N. BRAMLETTE Chapter G. Eocene Radiolaria By WILLIAM RIEDEL Chapter H. Smaller Foraminifera By RUTH TODD dhapter I. Larger Foraminifera By W. STORRS COLE ^Chapter J. Echinoids By C. WYTHE COOKE ~Part 4. Submarine Topography and Shoal-Water Ecology ^Chapter K. Submarine Topography and Shoal-Water Ecology By PRESTON E. CLOUD, JR.