DOCSLIB.ORG

Analysis of Composition and Chronology of Dome Emplacement

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Analysis of Composition and Chronology of Dome Emplacement ANALYSIS OF COMPOSITION AND CHRONOLOGY OF DOME EMPLACEMENT AT BLACK PEAK VOLCANO, ALASKA UTILIZING ASTER REMOTE SENSING DATA AND FIELD-BASED STUDIES A THESIS Presented to the Faculty of the University of Alaska Fairbanks In Partial Fulfillment of the Requirements For the Degree of MASTER OF SCIENCE By Jennifer Nicole Adleman, B.S. Fairbanks, Alaska May 2005 iii Abstract Black Peak volcano is a —3.5lcin-diameter caldera located on the Alaska Peninsula that formed —4,600 years ago in an eruption that excavated >101cm 3 of material. The caldera floor is occupied by at least a dozen overlapping dacitic to andesitic lava domes and flows. Examination of XRF results and observations of the domes in and around the caldera reveals a range of 57-65wt% Si0 2 and variations in amphibole content. Evidence for magma mixing includes vesicular enclaves and geochemical trends that indicate involvement of a more mafic magma into a dacitic reservoir. The purpose of this study is to investigate if, and how, these differences in composition and mineralogy are detectable in satellite emissivity and TIR data (ASTER) and compare the results to ground-based field observations to discern changes in the mineralogical and chemical properties of the domes. This study incorporates the use of decorrelation-stretch image processing techniques and the deconvolution of laboratory emissivity spectra to assess the viability of discriminating variations in the lithologies observed at Black Peak volcano. Compositional results from XRD and electron microprobe analyses are comparable to those obtained through deconvolution processing. Surfaces of <10% amphibole and Si02 of 60-65wt% and those that correspond to > 10% and <6 Iwt% Si02 are distinguishable in the ASTER data. iv Table of Contents Page Signature Page Title Page ii Abstract iii Table of Contents iv List of Figures vi List of Tables viii List of Appendices ix Acknowledgements Introduction 12 Background 19 2.1 Thermal Infrared (TIR) Remote Sensing Background 19 2.2 ASTER Satellite Background 23 2.3 Previous TIR Linear Deconvolution Compositional Studies 25 Methods 28 3.1 General Field Observations and Sampling Techniques 28 3.2 Analytical methods 30 3.2.1 Geochemical analysis 30 3.2.2 X-ray Diffraction 33 3 2 3 Laboratory Emission Spectra 33 3.2.4 Linear Deconvolution 34 3.3 ASTER Remote Sensing data processing 37 3.3.1 Decorrelation Stretch 37 3.3.2 ASTER derived emissivity and temperature 44 Results 45 4.1 Field results 45 4.2 Whole Rock geochemical analyses 52 Page 4.3 Petrologic Analyses 55 4.3.1 Microprobe 55 4.3.2 X-ray Diffraction 55 4.3.3 Laboratory emissivity spectra 63 4.3.4 Linear deconvolution 72 4.4 Satellite data 73 4.4.1 Decorrelation stretching 73 4.4.2 ASTER emissivity profiles 76 Discussion 77 5.1 Age relationships 77 5.2 ASTER satellite image relationships 78 5.2.1 Comparison of ASTER satellite imagery and bulk dome 78 rock compositions 5.2.2 Comparison of ASTER and laboratory emissivity spectra 80 and petrologic data 5.2.3 Comparison of ASTER pixel color, emissivity and 81 mineralogy 5 3 Implications for ASTER assessment of volcanic regions 83 5.3.1 Correlations between ASTER and petrologic studies: 83 what worked 5.3.2 Limitations at Black Peak, Alaska 84 5.3.3 Applications along the Alaska Peninsula and Aleutian Arc 86 Conclusion 88 References Cited 90 vi List of Figures Page Figure 1. Location map of Black Peak caldera and historically active volcanoes 13 Figure 2. ASTER spectral bands 16 Figure 3. Blackbody radiance curve 21 Figure 4. Annotated Color Infrared (CIR) aerial photo of Black Peak caldera 29 Figure 5. Example of a TIR color composite of the Black Peak caldera region 38 Figure 6. Schematic representation of the decorrelation stretch 40 Figure 7. Laboratory and ASTER emissivity spectra 43 Figure 8 Images of domes and features at Black Peak caldera 46 Figure 9. Subset of USGS Chignik (C-3) Quadrangle topographic map 48 Figure 10. Total alkali vs. silica (TAS) diagram of 2001 and 2003 samples 53 Figure 11. Harker diagrams of 2001 and 2003 Black Peak samples 54 Figure 12. Plagioclase and pyroxene ternary plots 56 Figure 13a. Section 1 summary of linear deconvolution, XRD and probe results 57 Section 2 summary of linear deconvolution, XRD and probe results 58 Section 2 summary of linear deconvolution, XRD and probe results 59 Section 2 summary of linear deconvolution, XRD and probe results 60 Section 3 summary of linear deconvolution, XRD and probe results 61 f. Additional blue pixel region samples linear deconvolution results 62 Figure 14a. Dry grass and snow laboratory emissivity 65 Section 1 laboratory and ASTER satellite emissivity spectra 66 Section 2 laboratory and ASTER satellite emissivity spectra 67 Section 2 laboratory and ASTER satellite emissivity spectra 68 Section 2 laboratory and ASTER satellite emissivity spectra 69 f Section 3 laboratory and ASTER satellite emissivity spectra 70 g. Additional blue pixel samples laboratory and ASTER emissivity 71 Figure 15. July 2000 ASTER VNIR FCC (3, 2, 1) 74 vii Page Figure 16. ASTER TIR bands 14, 12 and 10 decorrelation stretch 75 Figure Ala. Additional emissivity plots and pixel color of section 2 samples 137 Additional emissivity plot and pixel color of section 3 samples 138 Emissivity plot and pixel color samples 139 viii List of Tables Page Table 1. ASTER sensor specifics (JPL/NASA) 17 Table 2. ASTER scenes used in this study 18 Table 3. Electron microprobe settings 32 Table 4. End Member Spectral Library standards used in linear deconvolution 36 Table 5a. Section 1 Field sample descriptions 49 Section 2 Field sample descriptions 50 Section 3 Field samples, descriptions and petrology 51 Table Al. Section 1 additional field sample descriptions 98 Table A2. XRF Normalized Major Elements (weight %) 99 Table A3. XRF Unnormalized Trace Elements (ppm) 100 Table A4. ICP-MS Trace Elements (ppm) 101 Table A5. Probe analyses of pyroxene 104 Table A6. Probe analyses of amphibole 107 Table A7. Probe analyses of plagioclase 110 Table A8. X-ray diffraction analyses 119 Table A9a. Linear deconvolution results for section 1 121 Linear deconvolution results for section 2 123 Linear deconvolution results for section 3 130 d. Additional linear deconvolution results 132 Table A10. Additional analytical and pixel color results 136 ix List of Appendices Page Table A1. Section 1 additional field sample descriptions 98 Table A2. XRF Normalized Major Elements (weight %) 99 Table A3. XRF Unnormalized Trace Elements (ppm) 100 Table A4. ICP-MS Trace Elements (ppm) 101 Table AS. Probe analyses of pyroxene 104 Table A6. Probe analyses of amphibole 107 Table A7. Probe analyses of plagioclase 110 Table A8. X-ray diffraction analyses 119 Table A9a. Linear deconvolution results for section 1 121 Linear deconvolution results for section 2 123 Linear deconvolution results for section 3 130 d. Additional linear deconvolution results 132 Table A10. Additional analytical and pixel color results 136 Figure A Ia. Additional emissivity plots and pixel color of section 2 samples 137 Additional emissivity plot and pixel color of section 3 samples 138 Emissivity plot and pixel color samples 139 x Acknowledgements First and foremost I humbly thank Brian Epler, who has supported and assisted me throughout my graduate career. His daily smiles, culinary delights, ability to sort the laundry, and his support and love are tremendous contributions to my recent successes. My parents, George Adleman, Mona Zeftel and Lynn Collar have been incredibly understanding and supportive in my efforts to obtain a Masters degree. They have provided a never-ending stream of positive words, suggestions and contributions towards my goals, and I am very grateful for them. On a more academic note I thank my committee. My advisor Dr. Jessica Larsen spent numerous hours working with me in the field, in the lab and on paper to confirm my achievement in this endeavor. I am also grateful for the wisdom and advice Jess has given me in regards to Fairbanks and cabin life, dog ownership and job procurement. She is a great advisor, friend and neighbor. Dr. Michael Ramsey also spent numerous hours working with me in the field and laboratory. He has been a true wealth of knowledge in my academic pursuits. In fact it is Mike's presentation of similar research at the 2002 International Seismic-Volcanic Workshop of Kamchatkan-Aleutian Subduction Processes held in Fairbanks, Alaska that directed me down the path towards this study. His staff and graduate students Dr. Jeff Byrnes, Rachel Lee and Topher Hughes have been of great assistance to me in the preparation and analyses of my samples at their Pittsburgh facility. Dr. John Eichelberger and I have known each other for years, and it is through his positive and thoughtful leadership that I came to study at the University of Alaska Fairbanks. The opportunities which I have been afforded are in no uncertain terms due to Eich's ability to accomplish just about anything he puts his mind and heart to. Jess, Mike and I had a technique that needed a volcano, and Game McGimsey offered one. Tina Neal and Game McGimsey graciously offered to share their helicopter, time, field work and knowledge to a motley crew of student, petrologist and remote sensor without hesitation. I am grateful to Game for supporting my use of this technique in such an interesting petrologic region and for providing a field experience unparallel to any I have had the pleasure to be a part of Game also provided a great deal of enlightenment in xi regards to field preparations and trainings, the art of writing, and being a productive member of a terrific field crew.
Load more

Recommended publications
  • Abandonment of the Name Hartford Hill Rhyolitetuff and Adoption of New Formation Names for Middle Tertiary Ash-Flow Tuffs in the Carson City- Silver City Area, Nevada
    Abandonment of the Name Hartford Hill RhyoliteTuff and Adoption of New Formation Names for Middle Tertiary Ash-Flow Tuffs in the Carson City- Silver City Area, Nevada GEOLOGICAL SURVEY BULLETIN 1457-D Abandonment of the Name Hartford Hill Rhyolite Tuff and Adoption of New Formation Names for Middle Tertiary Ash-Flow Tuffs in the Carson City- Silver City Area, Nevada By EDWARD C. BINGLER CONTRIBUTIONS TO STRATIGRAPHY GEOLOGICAL SURVEY BULLETIN 1457-D UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1978 UNITED STATES DEPARTMENT OF THE INTERIOR CECIL D. ANDRUS, Secretary GEOLOGICAL SURVEY H. William Menard, Director Dingier, Edward C. Abandonment of the name Hartford Hill rhyolite tuff and adoption of new formation names for middle Tertiary ash-flow tuffs in the Carson City - Silver City area, Nevada (Contributions to stratigraphy) Geological Survey Bulletin 1457-D Supt. of Docs. No.: I 19.3: 1457-D Bibliography: p. D19 I. Geology, Stratigraphic-Tertiary. 2. Volcanic ash, tuff, etc.-Nevada- Carson City region. 3. Geology-Nevada-Carson City region. I. Title. II. Series. HI. Series: United States. Geological Survey. Bulletin 1457-D. QE75.B9 no. 1457-D [QE691] 557.3'08s [551.7'8] 78-606063 For sale by the Superintendent of Documents, U. S. Government Printing Office Washington, D. C. 20402 Stock Number 024-001-03124-8 CONTENTS Page Abstract___________________________________ Dl Introduction ______________________________________ 1 Acknowledgments ________________________________ 5 Ash-flow stratigraphy in the Carson City-Silver City area ___________ 7 Mickey Pass Tuff ________________________________ 7 Lenihan Canyon Tuff _____________________________ 8 Nine Hill Tuff _______________________________ 11 Eureka Canyon Tuff ______________________________ 14 Dacitetuff __________________________________ 16 Rhyolite tuff and augite rhyodacite tuff ___________________ 16 Santiago Canyon Tuff _____________________________ 17 References cited _____________________________^_____ 19 ILLUSTRATIONS Page FIGURE 1.
    [Show full text]
  • Sequences of Pleistocene Marine Terraces in the Santa Rosalia Area, Baja California Sur, Mexico
    275 SEQUENCES OF PLEISTOCENE MARINE TERRACES IN THE SANTA ROSALIA AREA, BAJA CALIFORNlA SUR, MEXICO Luc ORTLIEB Instituto de Geologfa, Univ. Nal. Aut6n. de Mexico & O.R.S.T.O.M. Apdo. Postal 1159 Hermosillo, Sonora, Mexico. ABSTRACT The coastal area near Santa Rosalla and on the eastern flank of the La Re­ forma volcanic complex, in eastcentral Baja California, presents an exceptional sequence of Pleistocene marine terraces. These remnants of past high stands of sea-level have been studied along 11 traverses roughly perpendicular to the coast­ line. The shorelines interpreted to correspond to distinct interglacial sea-level are regularly distributed at elevations varying from about + 9 m to + 190 m above mean sea level. A number of nine main shorelines were identified. Since no radio­ metric dates are yet available, a tentative chronostratigraphy of these features has been inferred from the V28-238 deep-sea core paleoclimatic curve; according to these correlations nine "interglacial" isotopic stages would be represented: one in early Late Pleistocene, six in Middle Pleistocene, and two in late Early Pleistocene. The Santa Rosalla Formation previously attributed to the base of the Pleistocene is thought to be a late Early Pleistocene (about 1 M. y.) inter­ glacial marine deposit. The vertical motions in the whole coastal area have prob­ ably been constant during the Quaternary although uplift rates are interpreted to have changed from a near value of 240 mrn/ka to approximately 130 mm/ka , at about 350 000 years B.P. RESUMEN La costa cerca de Santa Rosalfa y de la ladera oriental del complejo volca­ nico de La Reforma, en el noreste de Baja California Sur, presenta una secuencia excepcional de terrazas marinas pleistocenicas.
    [Show full text]
  • Plate Tectonics, Volcanic Petrology, and Ore Formation in the Santa Rosalia Area, Baja California, Mexico
    Plate tectonics, volcanic petrology, and ore formation in the Santa Rosalia area, Baja California, Mexico Item Type text; Thesis-Reproduction (electronic) Authors Schmidt, Eugene Karl, 1947- Publisher The University of Arizona. Rights Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author. Download date 01/10/2021 01:50:58 Link to Item http://hdl.handle.net/10150/555057 PLATE TECTONICS, VOLCANIC PETROLOGY, AND ORE FORMATION IN THE SANTA ROSALIA AREA, BAJA CALIFORNIA, MEXICO by Eugene Karl Schmidt A Thesis Submitted to the Faculty of the DEPARTMENT OF GEOSCIENCES In Partial Fulfillment of the Requirements For the Degree of MASTER OF SCIENCE In the Graduate College THE UNIVERSITY OF ARIZONA 1 9 7 5 z- STATEMENT BY AUTHOR This thesis has been submitted in partial ful­ fillment of requirements for an advanced degree at The University of Arizona and is deposited in the University Library to be made available to borrowers under rules of the Library. Brief quotations from this thesis are allowable without special permission, provided that accurate ac­ knowledgment of source is made. Requests for permission for extended quotation from or reproduction of this manu­ script in whole or in part may be granted by the head of the major department or the Dean of the Graduate College when in his judgment the proposed use of the material is in the interests of scholarship. In all other instances, however, permission must be obtained from the author.
    [Show full text]
  • Eruption Ages of Las Tres Virgenes Volcano (Baja California)
    ARTICLE IN PRESS Quaternary Geochronology xxx (2010) 1e9 Contents lists available at ScienceDirect Quaternary Geochronology journal homepage: www.elsevier.com/locate/quageo Research Paper Eruption ages of Las Tres Vírgenes volcano (Baja California): A tale of two helium isotopes Axel K. Schmitt a,*, Daniel F. Stockli b, Samuel Niedermann c, Oscar M. Lovera a, Brian P. Hausback d a Department of Earth and Space Sciences, University of California Los Angeles, 595 Charles Young Drive E, Los Angeles, CA 90095, USA b Department of Geology, University of Kansas, 120 Lindley Hall, 1475 Jayhawk Boulevard, Lawrence, KS 66045-7613, USA c Helmholtz-Zentrum Potsdam, Deutsches GeoForschungsZentrum, Telegrafenberg, D-14473 Potsdam, Germany d Geology Department, California State University, Sacramento, CA 95819-6043, USA article info abstract Article history: La Virgen tephra is the product of the youngest and most voluminous explosive eruption of Las Tres Received 4 September 2009 Vírgenes volcano (Baja California). Combined UeTh and (UeTh)/He zircon dating allows accurate Received in revised form correction for uranium-series disequilibrium, and yields an eruption age for La Virgen tephra of 11 February 2010 þ : 30:7 1 8 ka (2s). No difference in eruption ages was found between samples from proximal and distal La Accepted 15 February 2010 À1:4 Virgen tephra. A previously undated tephra south of Las Tres Vírgenes volcano yielded UeTh and (UeTh)/ Available online xxx He zircon ages overlapping those of La Virgen tephra, which suggests that both units are identical. 3He surface exposure ages (T3) of overlying mafic lavas are 25.5 Æ 4.4 and 22.0 Æ 2.5 ka, and agree within Keywords: 21 Uranium series uncertainties with Ne exposure ages (T21).
    [Show full text]
  • Geology of the Los Adobes Rancho Area, Sonora, Mexico, and Santa Cruz County, Arizona
    GEOLOGY OF THE LOS ADOBES RANCHO AREA, SONORA, MEXICO, AND SANTA CRUZ COUNTY, ARIZONA by WYATT G. GILBERT AND DAVID J. LAJACK November, 2000 Arizona Geological Survey Contributed Map CM OO-C In cooperation with Minefinders Corporation, Ltd. Arizona Geological Survey 416 W. Congress, Suite 100, Tucson, AZ 85701 Includes 5 page text, 1:24,000 scale geologic map and cross-sections (1 sheet) INTRODUCTION During the period April IS-October 18, 1996, the authors mapped the geology of about 110 square kilometers west of Nogales, Sonora, Mexico along the international border near Los Adobes Rancho for Minefinders Corporation, Ltd .. Approximately 46 days were spent in the field. SUMMARY OF GEOLOGY Reconnaissance geologic mapping focused primarily on the Mesozoic and Tertiary igneous and sedimentary rocks that lie both north and south of the main road into the area. No fossil or radiometric age data were obtained from the area, and age assignments, made on stratigraphic and intrusive relationships, are provisional at best. The oldest rocks in the map area include generally coarse terrigenous clastic units (KJsc, KJsI, KJs, KJc) that generally dip moderately northeast. Similar units mapped as the La Jareta Formation in the Planchas de Plata area just south of the map area (Segerstrom, 1987) and immediately north of the international border as the Salero Formation (Drewes, 1981) or as the Summit Conglomerate (informal) and/or Bisbee Formation (Riggs, 1987) are thought to be Jurassic or Cretaceous in age. These sedimentary units are overlain by felsic pyroclastic beds (KJft, KJftb) that are in turn overlain by dacite (KJd, KJdv, KJda).
    [Show full text]
  • Cerro Pizarro Volcano, Mexico by G. Carrasco-Nú
    1 Polygenetic nature of a rhyolitic dome and implications for hazard assessment: 2 Cerro Pizarro volcano, Mexico 3 by G. Carrasco-Núñez and N. Riggs 4 5 ABSTRACT 6 Rhyolitic domes are commonly regarded as monogenetic volcanoes associated with single, brief 7 eruptions. They are characterized by short-lived successions of pyroclastic and effusive activity 8 associated with a series of discrete eruptive events that apparently last on the order of years to 9 decades. Cerro Pizarro, a ~ 1.1 km3 rhyolitic dome in the eastern Mexican Volcanic Belt, shows 10 aspects of polygenetic volcanism including long-term repose periods (~ 50-80 ky) between 11 eruptions, chemical variations with time, and a complex evolution of alternating explosive and 12 effusive eruptions, a cryptodome phase, and sector collapse. This eruptive behavior provides 13 new insights into how rhyolite domes may evolve. A protracted, complex evolution bears 14 important implications for hazard assessment if reactivation of an apparently extinct rhyolitic 15 dome must be seriously considered. 16 17 Keywords: monogenetic volcanism, polygenetic volcanism, rhyolites, dome growth, volcanic 18 hazards, Mexican Volcanic Belt 19 20 INTRODUCTION 21 Monogenetic volcanoes comprise a wide spectrum of relatively small volcanic structures 22 (generally less than a few km3 erupted material) that show a commonly simple evolution (one 23 eruption, or a few clearly related eruptions), short life span (commonly years to decades for 24 mafic volcanoes, but possibly as much as a few centuries for rhyolitic domes), and minor 25 chemical composition changes. Monogenetic volcanoes are, in general, either basalt or rhyolite, 26 while polygenetic volcanoes, which erupt repeatedly and have a large and persistent magma 27 storage chamber, are commonly andesitic or dacitic in composition.
    [Show full text]
  • USGS Scientific Investigations Map 2832, Pamphlet
    Geologic Map of Mount Mazama and Crater Lake Caldera, Oregon By Charles R. Bacon Pamphlet to accompany Scientific Investigations Map 2832 View from the south-southwest rim of Crater Lake caldera showing the caldera wall from Hillman Peak on the west to Cleetwood Cove on the north. Crater Lake fills half of the 8- by 10-km-diameter caldera formed during the climactic eruption of Mount Mazama volcano approximately 7,700 years ago. Volcanic rocks exposed in the caldera walls and on the flanks record over 400,000 years of eruptive history. The exposed cinder cone and andesite lava flows on Wizard Island represent only 2 percent of the total volume of postcaldera volcanic rock that is largely covered by Crater Lake. Beyond Wizard Island, the great cliff of Llao Rock, rhyodacite lava emplaced 100–200 years before the caldera-forming eruption, dominates the northwest caldera wall where andesite lava flows at the lakeshore are approximately 150,000 years old. 2008 U.S. Department of the Interior U.S. Geological Survey This page intentionally left blank. CONTENTS Introduction . 1 Physiography and access . 1 Methods . 1 Geologic setting . 4 Eruptive history . 5 Regional volcanism . 6 Pre-Mazama silicic rocks . 6 Mount Mazama . 7 Preclimactic rhyodacites . 9 The climactic eruption . 10 Postcaldera volcanism . .11 Submerged caldera walls and floor . .11 Glaciation . .11 Geothermal phenomena . 12 Hazards . 13 Volcanic hazards . 13 Earthquake hazards . 14 Acknowledgments . 14 Description of map units . 14 Sedimentary deposits . 15 Volcanic rocks . 15 Regional volcanism, northwest . 15 Regional volcanism, southwest . 17 Mount Mazama . 20 Regional volcanism, east . 38 References cited .
    [Show full text]
  • 04Chapter3 Kavalieris.Pdf
    THE GEOLOGY AND GEOCHEMISTRY OF THE GUNUNG PANI GOLD PROSPECT, NORTH SULAWESI, INDONESIA by Imants Kavalieris A thesis submitted as the requirement for admission to the Degree of Master of Science at the Australian National University October 1984 -29- III. GEOLOGY OF THE PANI VOLCANIC COMPLEX AND RELATED ROCKS 3.1 Introduction The Pani Volcanic Complex (Fig. 5) consists of non-welded pyroclastics, breccias and massive or flow banded lava-like rhyodacites, essentially confined to a partly circular structure of about 3.5km diameter, within older granodiorite basement. The adjacent basement is extensively intruded by rhyodacite dykes and porphyritic microgranites. These rocks comprise more than 50% of the area within a 20km radius of the Pani Volcanic Complex. On the SW margin of the volcanic structure a dense dyke swarm appears structurally controlled mainly in an ESE direction. It has been concluded from these broad relation- ships that the Pani Volcanic Complex represents a deeply eroded remnant of an acid volcanic centre. The Pani Complex has at least one other major counterpart in the area, which reinforces this conclusion (the Tabulo ring- dyke Complex) . Description of rocks from the Tabulo structure are referred to in the following sections. 3.2 Lithology Mineralogically the Pani Complex igneous rocks are remarkably similar, although they comprise a wide range of textural types, from massive porphyritic rhyodacites to lapilli tuffs, agglomerates and volcanic breccia. Geology of the Pani Volcanic Complex {'_ ( ID~~_;_ Tpli ? ·· \ Hot Sprlno ) _.-_.·: .: : :t.·· Gunung .f? J j X ·.•··••·· \""'" : ~ X , X . \ LEGEND ~ "·· X ___ ,... s ....__ I ; .. ···"····/.. ~ X ~-te(!l-oO~o~ \ \ Rhyodacite lapilli tuff (Tpi +1[) ~ij·.,rx-~~":-:-':V"' .
    [Show full text]
  • Regional Tectonics and Resurgence in Pleistocene La Reforma Caldera Complex, Baja California Sur, Mexico
    Geophysical Research Abstracts Vol. 21, EGU2019-18699, 2019 EGU General Assembly 2019 © Author(s) 2019. CC Attribution 4.0 license. Regional tectonics and resurgence in Pleistocene La Reforma caldera complex, Baja California Sur, Mexico Claudia Pellicioli (1), Gianluca Groppelli (2), Roberto Sulpizio (3), Jose Luis Macias (4), and Laura Garcia-Sanchez (4) (1) Dipartimento di Scienze della Terra “Ardito Desio”, Università degli Studi di Milano, Milano, Italy, (2) Istituto per la Dinamica dei Processi Ambientali – Sezione di Milano, Consiglio Nazionale delle Ricerche, Milano, Italy, (3) Dipartimento di Scienze della Terra e Geoambientali, Università degli Studi di Bari Aldo Moro, Bari, Italy, (4) Instituto de Geofísica, Universidad Nacional Autónoma de México, Morelia, Michoacán, México La Reforma is a 10 km wide nested caldera complex close to the Santa Rosalía town (Baja California Sur, Mexico). Pleistocene calc-alkaline volcanic activity moved from La Reforma to Sierra Aguajito and finally to Las Tres Vírgenes complex (currently hosting the fourth largest producing geothermal field). The entire region is affected by an active transtensive tectonic regime (NW-SE trending right-lateral faults and NE-SW or N-S conjugate systems). Structures were partly inherited from the Gulf of California proto-gulf orthogonal extension and following oblique rifting phases. Detailed field mapping and structural analysis performed across La Reforma caldera complex during 2015-17 allowed the reconstruction of its geological and structural evolution, highlighting the key role of regional faults in influencing magma trapping and rise, geometry of the caldera collapse and resurgence processes. With regards to recognised evolution phases, a volcanic edifice was built in a shallow marine setting during the pre- caldera phase.
    [Show full text]
  • Petrology of the Keetley Volcanics in Summit and Wasatch Counties
    PETROLOGY OF THE KEETLEY VOLCANICS IN SUMMIT AND WASATCH COUNTIES, NORTH-CENTRAL UTAH A THESIS SUBMITTED TO THE FACULTY OF THE GRADUATE SCHOOL OF THE UNIVERSITY OF MINNESOTA BY ms SI EINARI LEVEINEN IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE MARCH, 1994 PETROLOGY OF THE KEETLEY VOLCANICS IN SUMMIT AND WASATCH COUNTIES, NORTH-CENTRAL UTAH A THESIS SUBMITTED TO THE FACULTY OF THE GRADUATE SCHOOL OF THE UNIVERSITY OF MINNESOTA BY JUSSI EINARI LEVEINEN IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE MARCH, 1994 Abstract The Keetley Volcanics rest subhorizontally in a structural saddle between the Uinta and Wasatch Mountains ca. 35 km east of Salt Lake City. The Keetley Volcanics consist essentially of Oligocene to Late Eocene volcanic breccias, sandstones, lava flows and porphyritic intrusives. Volcanic breccias are volumetrically the most important, being as thick as 500 m (total) in the vicinity of Keetley. Most of the breccias and intrusives are andesitic. Chemical compositions vary from trachyandesite to silica-poor rhyodacite. The relatively uniform compositions suggest a trachyandesitic source that differentiated by fractional crystallization in a relatively shallow chamber. Large porphyry intrusions are also present west of the Keetley Volcanics. Apparently, the Keetley Volcanics represent a part of magmatic events in the Uinta-Oquirrh mineral belt that started in Late Eocene and continued into earliest Miocene. The Keetley Volcanics may belong to a larger group of mid-Tertiary early to syn-extensional volcanic rocks that were formed before the gradual development of the San Andreas - Basin and Range transform-extensional system.
    [Show full text]
  • Estudio De Microsismicidad En La Caldera La Reforma Del Complejo Volcánico Y Geotérmico Las Tres Vírgenes, BCS
    Memorias del XXIII Congreso Anual – Morelia, Mich., 10-11 de marzo de 2016 Estudio de microsismicidad en la Caldera La Reforma del complejo volcánico y geotérmico Las Tres Vírgenes, BCS J.L. Pérez1*, E. Gómez-Arias2,3, L. Ávila-Barrientos2,3, A. González-Fernández3,4 y J.G. Acosta- Chang4 1Posgrado en Ciencias de la Tierra, Centro de Investigación Científica y de Educación Superior de Ensenada, Baja California, CICESE. 2Cátedras CONACYT – Centro de Investigación Científica y de Educación Superior de Ensenada, Baja California, CICESE. 3Centro Mexicano de Innovación en Energía Geotérmica, CeMIE-Geo. 4 División de Ciencias de la Tierra, Centro de Investigación Científica y de Educación Superior de Ensenada, Baja California, CICESE. * [email protected] Resumen En este trabajo se muestran los resultados preliminares de la primera etapa del estudio de microsismicidad en la caldera La Reforma del Complejo Volcánico de Las Tres Vírgenes (CVLTV), BCS, el cual tiene como fin verificar y localizar la actividad sísmica, contribuyendo de esta manera a mejorar la comprensión de dicha estructura y observar si existe una relación entre la actividad sísmica y un posible escenario geotérmico. Para este propósito, se han establecido dos campañas de instrumentación sísmica. La primera se llevó a cabo entre los meses de septiembre y octubre de 2015, verificándose la existencia de microsismicidad en la caldera y presentándose en este trabajo los resultados preliminares. Palabras clave: Caldera La Reforma, Red Sísmica, Microsismicidad, Geofísica. Microseismicity survey at La Reforma caldera in the geothermal and volcanic complex of Las Tres Vírgenes, BCS Abstract This work presents preliminary results of the first stage of a microseismicity survey conducted at Caldera La Reforma caldera in the Volcanic Complex of Las Tres Vírgenes, Baja California Sur, whose objective verify and locate microseismic activity.
    [Show full text]
  • Young Rhyodacite Dikes Found in the Queens Tunnel Beneath Woodside, Queens
    YOUNG RHYODACITE DIKES FOUND IN THE QUEENS TUNNEL BENEATH WOODSIDE, QUEENS Charles Merguerian Geology Department, 114 Hofstra University, Hempstead, NY 11549 Introduction One of the most scientifically startling and unforeseen discoveries made during detailed mapping of the subsurface geology of the Queens Tunnel has been the identification of a suite of red-colored, rhyodacite dikes ~800’ beneath Woodside, Queens. The dikes are found to crosscut Proterozoic granulite facies rocks of the Queens Tunnel Complex with which they are genetically and temporally unrelated. Field, geochemical, and petrographic studies all support the conclusion that the rocks are rhyodacitic in composition and exhibit textures and contact relationships typical of hypabyssal volcanic rocks. The shallow-level rhyodacite dikes are found to intrude a high-grade bedrock series that was exhumed from depths of roughly 40 km. The dikes cut gneissic layering, folds, and most faults in the tunnel but are cut by a relatively young NNE-trending fault system. The presence of relatively young rhyodacitic dikes proximate to their initial injection site adds a hitherto unknown volcanic formation the developmental geology of the NYC region. Geology of Western Queens, New York Studied by geologists for over 200 years, the durable crystalline rocks of New York City form the substrate for many civil and municipal engineering construction projects. Situated at the extreme southern end of the Manhattan Prong physiographic province of the New England Appalachians, New York City exposes a northeast-trending, deeply eroded sequence of metamorphosed Proterozoic to Lower Paleozoic rock. Although no natural bedrock is exposed along the Queens Tunnel alignment, borings indicate that the crystalline rocks of western Queens underlie a gentle SE-sloping nonconformity surface that projects upward to the location of Long Island Sound.
    [Show full text]