The Genesis of Oceanic Crust: Magma Injection, Hydrothermal Circulation
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Hawaii Volcanoes National Park Geologic Resources Inventory Report
National Park Service U.S. Department of the Interior Natural Resource Program Center Hawai‘i Volcanoes National Park Geologic Resources Inventory Report Natural Resource Report NPS/NRPC/GRD/NRR—2009/163 THIS PAGE: Geologists have lloongng been monimonittoorriing the volcanoes of Hawai‘i Volcanoes National Park. Here lalava cascades durduriingng the 1969-1971 Mauna Ulu eruption of Kīlauea VolVolcano. NotNotee the Mauna Ulu fountountaiain in the background. U.S. Geologiogicalcal SurSurvveyey PhotPhotoo by J. B. Judd (12/30/1969). ON THE COVER: ContContiinuouslnuouslyy eruptuptiingng since 1983, Kīllaueaauea Volcano contcontiinues to shapshapee Hawai‘Hawai‘i VoVollccanoes NatiNationalonal ParkPark.. Photo courtesy Lisa Venture/UniversiUniversitty of Cincinnati. Hawai‘i Volcanoes National Park Geologic Resources Inventory Report Natural Resource Report NPS/NRPC/GRD/NRR—2009/163 Geologic Resources Division Natural Resource Program Center P.O. Box 25287 Denver, Colorado 80225 December 2009 U.S. Department of the Interior National Park Service Natural Resource Program Center Denver, Colorado The National Park Service, Natural Resource Program Center publishes a range of reports that address natural resource topics of interest and applicability to a broad audience in the National Park Service and others in natural resource management, including scientists, conservation and environmental constituencies, and the public. The Natural Resource Report Series is used to disseminate high-priority, current natural resource management information with managerial application. The series targets a general, diverse audience, and may contain NPS policy considerations or address sensitive issues of management applicability. All manuscripts in the series receive the appropriate level of peer review to ensure that the information is scientifically credible, technically accurate, appropriately written for the intended audience, and designed and published in a professional manner. -
Poroelastic Responses of Confined Aquifers to Subsurface Strain And
Solid Earth, 6, 1207–1229, 2015 www.solid-earth.net/6/1207/2015/ doi:10.5194/se-6-1207-2015 © Author(s) 2015. CC Attribution 3.0 License. Poroelastic responses of confined aquifers to subsurface strain and their use for volcano monitoring K. Strehlow, J. H. Gottsmann, and A. C. Rust School of Earth Sciences, University of Bristol, Wills Memorial Building, Bristol BS8 1RJ, UK Correspondence to: K. Strehlow ([email protected]) Received: 11 May 2015 – Published in Solid Earth Discuss.: 9 June 2015 Revised: 18 September 2015 – Accepted: 21 October 2015 – Published: 10 November 2015 Abstract. Well water level changes associated with mag- aquifer and are commonly neglected in analytical models. matic unrest can be interpreted as a result of pore pressure These findings highlight the need for numerical models for changes in the aquifer due to crustal deformation, and so the interpretation of observed well level signals. However, could provide constraints on the subsurface processes caus- simulated water table changes do indeed mirror volumetric ing this strain. We use finite element analysis to demonstrate strain, and wells are therefore a valuable addition to monitor- the response of aquifers to volumetric strain induced by pres- ing systems that could provide important insights into pre- surized magma reservoirs. Two different aquifers are invoked eruptive dynamics. – an unconsolidated pyroclastic deposit and a vesicular lava flow – and embedded in an impermeable crust, overlying a magma chamber. The time-dependent, fully coupled models simulate crustal deformation accompanying chamber pres- 1 Introduction surization and the resulting hydraulic head changes as well as flow through the porous aquifer, i.e. -
Hydrothermal Circulation Within the Endeavour Segment; Juan De Fuca Ridge
Hydrothermal Circulation within the Endeavour Segment; Juan de Fuca Ridge H. Paul Johnson1, Maurice A. Tivey2, Tor A. Bjorklund1, and Marie S. Salmi1 1School of Oceanography, University of Washington, Seattle, WA 98195-7940 2Department of Geology and Geophysics Woods Hole Oceanographic Institution Woods Hole, MA 02543 Correspondence should be addressed to HPJ, [email protected] 206-543-8474 Hydrothermal Circulation within the Endeavour Segment; Juan de Fuca Ridge Abstract Areas of the seafloor at mid-ocean ridges where hydrothermal vents discharge are easily recognized by the dramatic biological, physical and chemical processes that characterize such sites. Locations where seawater flows into the seafloor to recharge hydrothermal cells within the crustal reservoir are by contrast almost invisible, but can be indirectly identified by a systematic grid of conductive heat flow measurements. An array of conductive heat flow stations in the Endeavour axial valley of the Juan de Fuca Ridge has identified recharge zones that appear to represent a nested system of fluid circulation paths. At the scale of an axial rift valley, conductive heat flow data indicate a general cross-valley fluid flow, where seawater enters the shallow sub-surface crustal reservoir at the eastern wall of the Endeavour axial valley and undergoes a kilometer of horizontal transit beneath the valley floor, finally exiting as warm hydrothermal fluid discharge on the western valley bounding wall. Recharge zones also have been identified as located within an annular ring of very cold seafloor around the large Main Endeavour Hydrothermal Field, with seawater inflow occurring within faults that surround the fluid discharge sites. -
Three-Dimensional Models of Hydrothermal Circulation Through a Seamount Network on Fast-Spreading Crust ∗ Rachel M
Earth and Planetary Science Letters 501 (2018) 138–151 Contents lists available at ScienceDirect Earth and Planetary Science Letters www.elsevier.com/locate/epsl Three-dimensional models of hydrothermal circulation through a seamount network on fast-spreading crust ∗ Rachel M. Lauer a,b,c, , Andrew T. Fisher b,c, Dustin M. Winslow b,c,d a Department of Geoscience, University of Calgary, Calgary, Alberta, Canada b Earth and Planetary Sciences Department, University of California, Santa Cruz, 95064, USA c Center for Dark Energy Biosphere Investigations, University of California, Santa Cruz, 95064, USA d GrowthIntel, 25-27 Horsell Road, London N5 1XL, UK a r t i c l e i n f o a b s t r a c t Article history: We present results from three-dimensional, transient, fully coupled simulations of fluid and heat Received 25 February 2018 transport on a ridge flank in fast-spread ocean crust. The simulations quantify relationships between rates Received in revised form 17 July 2018 of fluid flow, the extent of advective heat extraction, the geometry of crustal aquifers and outcrops, and Accepted 14 August 2018 crustal hydrologic parameters, with the goal of simulating conditions similar to those seen on 18–24 M.y. Available online xxxx old seafloor of the Cocos plate, offshore Costa Rica. Extensive surveys of this region documented a Editor: M. Bickle 2 ∼14,500 km area of the seafloor with heat flux values that are 10–35% of those predicted from Keywords: conductive cooling models, and identified basement outcrops that serve as pathways for hydrothermal hydrothermal circulation circulation via recharge of bottom water and discharge of cool hydrothermal fluid. -
Depth of Magma Chamber Determined by Experimental Petrologic Methods
DEPTH OF MAGMA CHAMBER DETERMINED BY EXPERIMENTAL PETROLOGIC METHODS Akihiko Tomiya Geological Survey of Japan, 1-1-3, Higashi, Tsukuba, Ibaraki, Japan Keywords: magma chamber, experimental petrology, Usu magma and, therefore, the composition of the residual melt, volcano, deep-seated geothermal resource that is, the evolved magma. ABSTRACT Thermodynamic conditions of a magma chamber can be estimated using petrographic information (e.g., compositions Depth of magma chamber (or young intrusive body) is one of and modal fractions of phenocrysts and groundmass) from a the most important parameters that determine the thermal representative rock erupted from the chamber. In order to structure and the circulation pattern of fluid around a estimate the pressure of magma chamber, the following geothermal area. The depth is also important when we methods are generally used; (1) geobarometer, (2) water recognize the magma chamber as a deep-seated geothermal content, and (3) melting experiment. One of the examples of resource itself. Here, we introduce an experimental petrologic the first method is an amphibole geobarometer (e.g., method for determining the depth of magma chamber. There Hammarstrom and Zen, 1986) where pressure is estimated are several methods in order to determine the depth (pressure) from the aluminum content of the amphibole crystallized from of a magma chamber. Among them, a melting experiment for the magma. This method, however, is difficult to apply to the rock erupted from the magma chamber is the most reliable natural magma because the geobarometer should be applied method. The method consists of the following procedure: (1) only when the mineral assemblage of the magma is the same as Select a sample (volcanic rock) which is representative of that of experimental products for which the geobarometer was magma in the chamber; (2) Give a petrographic description of calibrated. -
150 Geologic Facts About California
California Geological Survey - 150th Anniversary 150 Geologic Facts about California California’s geology is varied and complex. The high mountains and broad valleys we see today were created over long periods of time by geologic processes such as fault movement, volcanism, sea level change, erosion and sedimentation. Below are 150 facts about the geology of California and the California Geological Survey (CGS). General Geology and Landforms 1 California has more than 800 different geologic units that provide a variety of rock types, mineral resources, geologic structures and spectacular scenery. 2 Both the highest and lowest elevations in the 48 contiguous states are in California, only 80 miles apart. The tallest mountain peak is Mt. Whitney at 14,496 feet; the lowest elevation in California and North America is in Death Valley at 282 feet below sea level. 3 California’s state mineral is gold. The Gold Rush of 1849 caused an influx of settlers and led to California becoming the 31st state in 1850. 4 California’s state rock is serpentine. It is apple-green to black in color and is often mottled with light and dark colors, similar to a snake. It is a metamorphic rock typically derived from iron- and magnesium-rich igneous rocks from the Earth’s mantle (the layer below the Earth’s crust). It is sometimes associated with fault zones and often has a greasy or silky luster and a soapy feel. 5 California’s state fossil is the saber-toothed cat. In California, the most abundant fossils of the saber-toothed cat are found at the La Brea Tar Pits in Los Angeles. -
Discovery of a Hydrothermal Fissure in the Danakil Depression
EPSC Abstracts Vol. 12, EPSC2018-381-1, 2018 European Planetary Science Congress 2018 EEuropeaPn PlanetarSy Science CCongress c Author(s) 2018 Discovery of a hydrothermal fissure in the Danakil depression Daniel Mège (1), Ernst Hauber (2), Mieke De Craen (3), Hugo Moors (3) and Christian Minet (2) (1) Space Research Centre, Polish Academy of Sciences, Poland ([email protected]), (2) DLR, Germany ([email protected], [email protected], (3) Belgian Nuclear Research Centre, Belgium ([email protected], [email protected]) Abstract Oily Lake and Gaet’Ale). It is manifested by (1) salt polygon geometry directly influenced by the underlying Volcanic rift zones are among the most emblematic fracture; (2) bubbling pools; (3) dead pools; (4) shallow analogue features on Earth and Mars [1-2], with expected sinkholes; (4) a variety of other micromorphologies differences mainly resulting from the different value of a related to free or pressurised upflow of gas and fluids; single parameter, gravity [3]. Beyond the understanding and (5) rare evidence of fumarolic activity. In this context, of the geology, rift zones provide appropriate the Yellow Lake appears as a possible salt karst feature hydrothermal environments for the development of [10] the location and growth of which is controlled by micro-organisms in extreme conditions which depend at relay zone deformation between the fissure segments. first order on endogenic processes, and weakly on the planetary climate conditions. The Europlanet 2018 3. Hydrothermal fluids Danakil field campaign enabled identifying a previously The physico-chemistry of fluids and minerals from two unreported 4.5 km long hydrothermal fissure on the Lake small pools located along the Yellow Lake Fissure, as Asale salt flats, the Erta Ale - Dallol segment of the well as the Yellow Lake, have been analysed (Table 1). -
Mantle Hydration and Cl-Rich Fluids in the Subduction Forearc Bruno Reynard1,2
Reynard Progress in Earth and Planetary Science (2016) 3:9 Progress in Earth and DOI 10.1186/s40645-016-0090-9 Planetary Science REVIEW Open Access Mantle hydration and Cl-rich fluids in the subduction forearc Bruno Reynard1,2 Abstract In the forearc region, aqueous fluids are released from the subducting slab at a rate depending on its thermal state. Escaping fluids tend to rise vertically unless they meet permeability barriers such as the deformed plate interface or the Moho of the overriding plate. Channeling of fluids along the plate interface and Moho may result in fluid overpressure in the oceanic crust, precipitation of quartz from fluids, and low Poisson ratio areas associated with tremors. Above the subducting plate, the forearc mantle wedge is the place of intense reactions between dehydration fluids from the subducting slab and ultramafic rocks leading to extensive serpentinization. The plate interface is mechanically decoupled, most likely in relation to serpentinization, thereby isolating the forearc mantle wedge from convection as a cold, potentially serpentinized and buoyant, body. Geophysical studies are unique probes to the interactions between fluids and rocks in the forearc mantle, and experimental constrains on rock properties allow inferring fluid migration and fluid-rock reactions from geophysical data. Seismic velocities reveal a high degree of serpentinization of the forearc mantle in hot subduction zones, and little serpentinization in the coldest subduction zones because the warmer the subduction zone, the higher the amount of water released by dehydration of hydrothermally altered oceanic lithosphere. Interpretation of seismic data from petrophysical constrain is limited by complex effects due to anisotropy that needs to be assessed both in the analysis and interpretation of seismic data. -
Fs20193026.Pdf
Prepared in collaboration with U.S. Forest Service, Bureau of Land Management, U.S. Environmental Protection Agency, Colorado Division of Reclamation Mining and Safety, Colorado Department of Public Health and Environment, and Animas River Stakeholders Group Geological and Geophysical Data for a Three-Dimensional View— Inside the San Juan and Silverton Calderas, Southern Rocky Mountains Volcanic Field, Silverton, Colorado This study integrates geological and geophysical data important for developing a three-dimensional (3D) model of the San Juan-Silverton caldera complex. The project aims to • apply state-of-the-art geophysical data processing techniques to legacy data; • map subsurface lithologies, faults, vein structures, and surficial deposits that may be groundwater flow paths; • better understand geophysical response of mineral systems at depth; and • provide geological and geophysical frameworks that will inform mining reclamation decisions and mineral resource assessments. Introduction shallow properties important for understanding surface water and groundwater quality issues and will also improve knowl- The San Juan-Silverton caldera complex located near edge of deep geological structures that may have been conduits Silverton, Colorado, in the Southern Rocky Mountains volcanic for hydrothermal fluids that formed mineral deposits (fig. 1). field is an ideal natural laboratory for furthering the under- The study has general applications to mineral resource assess- standing of shallow-to-deep volcanic-related mineral systems. ments -
Physiography of the Seafloor Hypsometric Curve for Earth’S Solid Surface
OCN 201 Physiography of the Seafloor Hypsometric Curve for Earth’s solid surface Note histogram Hypsometric curve of Earth shows two modes. Hypsometric curve of Venus shows only one! Why? Ocean Depth vs. Height of the Land Why do we have dry land? • Solid surface of Earth is Hypsometric curve dominated by two levels: – Land with a mean elevation of +840 m = 0.5 mi. (29% of Earth surface area). – Ocean floor with mean depth of -3800 m = 2.4 mi. (71% of Earth surface area). If Earth were smooth, depth of oceans would be 2450 m = 1.5 mi. over the entire globe! Origin of Continents and Oceans • Crust is formed by differentiation from mantle. • A small fraction of mantle melts. • Melt has a different composition from mantle. • Melt rises to form crust, of two types: 1) Oceanic 2) Continental Two Types of Crust on Earth • Oceanic Crust – About 6 km thick – Density is 2.9 g/cm3 – Bulk composition: basalt (Hawaiian islands are made of basalt.) • Continental Crust – About 35 km thick – Density is 2.7 g/cm3 – Bulk composition: andesite Concept of Isostasy: I If I drop a several blocks of wood into a bucket of water, which block will float higher? A. A thick block made of dense wood (koa or oak) B. A thin block made of light wood (balsa or pine) C. A thick block made of light wood (balsa or pine) D. A thin block made of dense wood (koa or oak) Concept of Isostasy: II • Derived from Greek: – Iso equal – Stasia standing • Density and thickness of a body determine how high it will float (and how deep it will sink). -
The Nature of the Mohorovicic Discontinuity, a Compromise 1
JOURNAL OF GEOPHYSICAL RESEARCH VOL. 68, No. 15 AUGUST 1, 1963 The Nature of the Mohorovicic Discontinuity, A Compromise 1 PETER J. WYLLIE Department of Geochemistry and Minemlogy Pennsylvania State Universit.y, University Park Abstract available . The experimental data and steady-state calculations make it difficult M to explain the discontinuity beneath both oceans and continents on the basis of the same change. The phase oceanic M discontinuity may be a chemical discontinuity between basalt and peridotite , and a similar chemical discontinuity ma,y thus be expected b�neath the conti nents. Since ayailable experimental data place the basalt-eclogite phase change at about thE' same depth as the continental M discontinuity, intersections may exist between a zone of chemical discontinuity and a phase transition zone, the transition being either basalt-ecloO"ite or feldspathic peridotite-garnet peridotite. Detection of the latter transition by seismic t�'h niques ma,y be difficult. The M discontinuity could therefore represent the basalt-eclogite phase change in some localities (e.g. mountain belts) and the chemical discontinuity in others (e.g. oceans and continental shields). Variations in the depth to the chemical discontinuity and in the positions of geoisotherms produce great flexibility in oro genetic models. Interse; tions between the two zones at depth could be reflected at the surface by major fault zones separating large structural blocks of different elevations. Chemical discontinuity. The conyentional termediate between dunite and basalt is view that the Moho discontinuity at the base of qualitatively reasonable for the mantle. the crust is caused by a chemical change from Ringwood [1962a, c] adopted a specific model basaltic rock to peridotite has been expounded compounded from the concepts advanced and recently by Hess [1955], Wager [1958], and developed by many petrologists and geochem Harris and Rowell [1960]. -
27. Chinook Trough Rifting and Hydrothermal Deposition at Sites 885 and 8861
Rea, D.K., Basov, I.A., Scholl, D.W., and Allan, J.F. (Eds.), 1995 Proceedings of the Ocean Drilling Program, Scientific Results, Vol. 145 27. CHINOOK TROUGH RIFTING AND HYDROTHERMAL DEPOSITION AT SITES 885 AND 8861 Gerald R. Dickens2 and Robert M. Owen2 ABSTRACT The Chinook Trough is a pronounced deep located in the central North Pacific Ocean that spans approximately 1500 km in a northeast-southwest direction. Geophysical and geomorphological considerations suggest that this feature is the southern litho- spheric scar marking initiation of Late Cretaceous north-south rifting within the ancient Farallon Plate. If this hypothesis is correct, then, by analogy to other active and passive mid-ocean rift zones, Late Cretaceous sediment deposited immediately south of the Chinook Trough should contain significant amounts of hydrothermal material deposited in association with the intraplate rifting event. Because the proposed tectonic origin for the Chinook Trough places seafloor south of the eastern end of the trough beneath the Cretaceous calcite compensation depth (CCD), expected hydrothermal components deposited during the Late Cretaceous at these locations also should lack carbonate dilution. Ocean Drilling Program Sites 885 and 886 were drilled approximately 60 km south of the northeast section of the Chinook Trough. High-resolution chemical and mineralogical analyses demonstrate that sediment deposited after 75-81 Ma at these sites contains an extensive record of hydrothermal deposition without associated carbonate. Various proxy indicators