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Cooliog and Crystaliizatiqii of Tholeiitic Basalt, 1965 Makaopuhi

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Cooliog and Crystaliizatiqii of Tholeiitic Basalt, 1965 Makaopuhi Cooliogy-s: s-j *, and"-§•" CrystaliizatiQii>•*. tl* •* of/^ Tholeiitic Basalt, 1965 MakaOpuhi Lava Lake, Hawaii GEOLOGICAL SURV1Y PROFESSIONAL PAPER 1004 Cooling and Crystallization of Tholeiitic Basalt, 1965 Makaopuhi Lava Lake, Hawaii By THOMAS L. WRIGHT and REGINALD T. OKAMURA GEOLOGICAL SURVEY PROFESSIONAL PAPER 1004 An account of the 4-year history of cooling, crystallization, and differentiation of tholeiitic basalt from one of Kilauea's lava lakes UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1977 UNITED STATES DEPARTMENT OF THE INTERIOR CECIL D. ANDRUS, Secretary GEOLOGICAL SURVEY V. E. McKelvey, Director Library of Congress Cataloging in Publication Data Wright, Thomas Loewelyn. Cooling and crystallization of tholeiitic basalt, 1965 Makaopuhi Lava Lake, Hawaii. (Geological Survey Professional Paper 1004) Includes bibliographical references. Supt. of Docs. No.: 119.16:1004 1. Basalt-Hawaii-Kilauea. I. Okamura, Reginald T., joint author. II. Title. III.Title: Makaopuhi Lava Lake, Hawaii. IV. Series: United States. (Geological Survey. Professional Paper 1004) QE462.B3W73 552'.2 76-608264 For sale by the Superintendent of Documents, U.S. Government Printing Office Washington, D.C. 20402 Stock number 024-001-02990-1 CONTENTS Page Page Abstract____________________________________ 1 Observations—Continued Introduction ______________________________ 1 Oxygen fugacity measurements ______________ 18 Acknowledgments ____________________________ 2 Changes in surface altitude_________ ——— ——— ____ 24 Previous work ___________________________ 2 Chemical and petrographic studies ____________—25 The eruption of March 5-15, 1965 __________________ 2 Major element chemistry ______________—25 Chronology ________________________ 2 Petrography ______________________— 31 Initial conditions following formation of a permanent Distribution of olivine ________________ 36 crust __________________________________ 3 Variation in grain size ____——— ——— _________ 36 Definition of "crust" and "melt" __ ___ _ _ __ _____ __ 4 Core density and vesicle distribution ______ 36 Methods of study __ ___ _ ___ __ __ ____ _ __ _ _ _ 5 Discussion__________________________— 37 Measurement of surface altitude changes _________ 5 Chemical differentiation in the lava lake _________— 40 Core drilling--_____________________________ 5 Gravitative settling of olivine ________________—40 Sampling of melt and casing drill holes below the crust-melt Flow differentiation of olivine-augite-plagioclase ——————47 interface ________________________ 8 Segregation veins ____—_______——— ——— _________ 42 Measurement of temperature _______________ 8 Convective cooling in the lava lake _____________— 44 Additional field studies ________________________ 9 High-temperature oxidation of basalt _____ ___ _ ___ — 45 Observations _______________________________ 10 Interpretation of surface altitude changes __________ — 46 Thermal history ______________________^__10 Summary: Cooling and solidification history of Makaopuhi lava Temperature of the crust-melt interface ___ _ ___16 lake__________________________________46 Cooling of the crust (T<1,070°C) _____________16 References cited _________________ ——— ——— ____47 Cooling of the melt (T>1,070°C)______________18 ILLUSTRATIONS Page FIGURE 1. Index map showing Kilauea lava lakes _____________________________________________ 2 2. Photograph showing posteruption surface, Makaopuhi lava lake _____________________________ ————— _ 3 3. Index map showing surface features of Makaopuhi lava lake ____________________________ 4 4. Schematic cross section, west pit of Makaopuhi crater _____________________________________ 4 5. Photographs of tramway used to transport equipment, 1965-67 _______________________________ 5 6. Photographs of tramway used to transport equipment, 1968-69 ________________________________ 6 7. Photograph of portable drill rig used in 1965-66 _________________________________________ 7 8. Photographs of trailer-mounted drill rig used in 1968-69 ______________________________________ 7 9. Photographs of field studies __________ ____________________________________________ 10 10. Diagram showing isotherms plotted as a function of square root of time and depth ______________——__——— 11 11. Diagram showing logfQz plotted against the reciprocal of absolute temperature for profiles obtained in 11 drill holes 18 12. Maps showing contoured altitude changes on the surface of Makaopuhi lava lake_____________ ———— ——— 21 13. Maps showing tilting of the surface of Makaopuhi lava lake______________________________ __—— 24 14. Diagram showing volume rate of subsidence or uplift plotted against square root of time ______ —— __ ——— ——— 25 15. MgO variation diagrams ________________________________________________________——— 30 16-23. Diagrams showing: 16. Modal data plotted as percent minerals against percent glass ______________________________ 34 17. Percent glass plotted against collection temperature ________________________________. 35 18. Weight percent minerals plotted against temperature______________________________. 35 19. Schematic distribution of large (>1 mm diam) olivine crystals in drill holes 68-1 and 68-2 ___________ 37 20. Median volumes of augite, plagioclase, ilmenite, and vesicles plotted against depth ______________ 39 21. Bulk density of drill core plotted against depth_____________________________________. 40 22. Results of differentiation calculations: percent crystals removed plotted against depth _____________. 41 23. Results of differentiation calculations: composition and amount of olivine, augite, and plagioclase plotted against amount of residual liquid ______________________________________________ 42 24. Photographs of drill core for 68-1 __________________________________________________ 50 25. Photographs of drill core for 68-2 _________ ________________________________________ 51 26. Photographs of drill core for 69-1 _________ ________________________________________ 52 27. Temperature profiles: uncorrected _________________________________________________ 53 28. Temperature profiles: corrected for contamination __ ________________________________________ 57 in IV CONTENTS TABLES Page TABLE 1. Contamination effects of thermocouple elements used in Makaopuhi lava lake _ _ __ __ ___ _ ___ ———— - 1 2. Depth to isothermal surfaces in the upper crust of Makaopuhi lava lake ____________ ————— —— —— ——— --—— 12 3. Temperature profiles used to construct isotherms in the melt of Makaopuhi lava lake ____________——— 15 4. Depth to crust-melt interface determined from drilling, and temperatures measured following drilling in Makaopuhi lava lake __________________________________________________——— 17 5. Melting point data for Ag (961°C), Au (1,063°C), and GeO2 (1,115±40C) _______-______________________ 17 6. Rainfall record at Makaopuhi crater_____________________________________- — —— 17 7. Summary of observations on oxygen fugacity profiles _____________________-______ —— — -— 21 8. Volume of subsidence/uplift determined from surface altitude changes, Makaopuhi lava lake __ ——— ____ ——— __ 25 9. Sample data for chemical analyses shown in tables 10 and 11 ______________ — ___ —— ———— _ ——— ——— __ 26 10. Major element chemical analyses, Makaopuhi lava lake: samples collected in 1965-66 —___ —— ______—————— 27 11. Major element chemical analyses, Makaopuhi lava lake: samples collected in 1968-69 ___________ — —— 28 12. Average composition of pumice (MPUMAV) erupted into Makaopuhi lava lake, March, 1965 ____________—— 31 13. Modal data, Makaopuhi lava lake ________________________________________________________ 32 14. Chemical mode for MPUMAV, Makaopuhi lava lake _____________________________________—— 34 15. Mineral paragenesis, Makaopuhi lava lake _______________________________________ —— __ 35 16. Temperature of melt samples estimated in two different ways ______________________-- — — — —— 36 17. Composition of residual glass from Makaopuhi and Alae lava lakes _______________-___ —————— ————— 37 18. Summary of grain-size measurements for analyzed samples from drill holes 68-1 and 68-2 ——__________ ———— _ 38 19. Volumes of crystals and vesicles; samples from drill holes 68-1 and 68-2_______________________———— 38 20. Density of drill core from holes 1-23, 1965-66 and hole 68-2 _________________________________ 39 21. Adjusted modal data for differentiated melt samples from drill holes 68-1, 68-2, and 69-1 ______________ 43 22. Results of mixing calculations for segregation veins ________________ _______________ 43 23. Attitudes of segregation veins, Makaopuhi lava lake __________________________________________ 44 24. Core logs for drill holes 1-24, 1965-66___________________________________________— 60 25. Core logs for drill holes 68-1, 68-2, and 69-1; 1968-69 __________________________________— 65 26. Temperature profiles measured in drill holes 2-24, 68-1 ____________________-____________ 66 27. Oxygen-fugacity profiles, Makaopuhi lava lake______________________________________———— 73 28. Altitudes obtained by leveling the surface of Makaopuhi lava lake __________ —— — ___ —— —— ——— ————— 74 29. Altitudes and differences corrected for ground tilt associated with the December 25,1965, and October, 1968, East rift eruptions ___________________________________________________________ 78 COOLING AND CRYSTALLIZATION OF THOLEIITIC BASALT, 1965 MAKAOPUHI LAVA LAKE, HAWAII By THOMAS L. WRIGHT and REGINALD T. OKAMURA ABSTRACT the melt. Segregation veins have compositions explainable by low- temperature (1,030°-1,070°C)
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