(Gravity) Oceanic Vs. Continental Crust Continental Crust
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Preliminary Catalog of the Sedimentary Basins of the United States
Preliminary Catalog of the Sedimentary Basins of the United States By James L. Coleman, Jr., and Steven M. Cahan Open-File Report 2012–1111 U.S. Department of the Interior U.S. Geological Survey U.S. Department of the Interior KEN SALAZAR, Secretary U.S. Geological Survey Marcia K. McNutt, Director U.S. Geological Survey, Reston, Virginia: 2012 For more information on the USGS—the Federal source for science about the Earth, its natural and living resources, natural hazards, and the environment, visit http://www.usgs.gov or call 1–888–ASK–USGS. For an overview of USGS information products, including maps, imagery, and publications, visit http://www.usgs.gov/pubprod To order this and other USGS information products, visit http://store.usgs.gov Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Although this information product, for the most part, is in the public domain, it also may contain copyrighted materials as noted in the text. Permission to reproduce copyrighted items must be secured from the copyright owner. Suggested citation: Coleman, J.L., Jr., and Cahan, S.M., 2012, Preliminary catalog of the sedimentary basins of the United States: U.S. Geological Survey Open-File Report 2012–1111, 27 p. (plus 4 figures and 1 table available as separate files) Available online at http://pubs.usgs.gov/of/2012/1111/. iii Contents Abstract ...........................................................................................................................................................1 -
The Evolution of a Heterogeneous Martian Mantle: Clues from K, P, Ti, Cr, and Ni Variations in Gusev Basalts and Shergottite Meteorites
Earth and Planetary Science Letters 296 (2010) 67–77 Contents lists available at ScienceDirect Earth and Planetary Science Letters journal homepage: www.elsevier.com/locate/epsl The evolution of a heterogeneous Martian mantle: Clues from K, P, Ti, Cr, and Ni variations in Gusev basalts and shergottite meteorites Mariek E. Schmidt a,⁎, Timothy J. McCoy b a Dept. of Earth Sciences, Brock University, St. Catharines, ON, Canada L2S 3A1 b Dept. of Mineral Sciences, National Museum of Natural History, Smithsonian Institution, Washington, DC 20560-0119, USA article info abstract Article history: Martian basalts represent samples of the interior of the planet, and their composition reflects their source at Received 10 December 2009 the time of extraction as well as later igneous processes that affected them. To better understand the Received in revised form 16 April 2010 composition and evolution of Mars, we compare whole rock compositions of basaltic shergottitic meteorites Accepted 21 April 2010 and basaltic lavas examined by the Spirit Mars Exploration Rover in Gusev Crater. Concentrations range from Available online 2 June 2010 K-poor (as low as 0.02 wt.% K2O) in the shergottites to K-rich (up to 1.2 wt.% K2O) in basalts from the Editor: R.W. Carlson Columbia Hills (CH) of Gusev Crater; the Adirondack basalts from the Gusev Plains have more intermediate concentrations of K2O (0.16 wt.% to below detection limit). The compositional dataset for the Gusev basalts is Keywords: more limited than for the shergottites, but it includes the minor elements K, P, Ti, Cr, and Ni, whose behavior Mars igneous processes during mantle melting varies from very incompatible (prefers melt) to very compatible (remains in the shergottites residuum). -
Thermal and Crustal Evolution of Mars Steven A
JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 107, NO. E7, 10.1029/2001JE001801, 2002 Thermal and crustal evolution of Mars Steven A. Hauck II1 and Roger J. Phillips McDonnell Center for the Space Sciences and Department of Earth and Planetary Sciences, Washington University, Saint Louis, Missouri, USA Received 11 October 2001; revised 4 February 2002; accepted 11 February 2002; published 16 July 2002. [1] We present a coupled thermal-magmatic model for the evolution of Mars’ mantle and crust that may be consistent with estimates of the average crustal thickness and crustal growth rate. By coupling a simple parameterized model of mantle convection to a batch- melting model for peridotite, we can investigate potential conditions and evolutionary paths of the crust and mantle in a coupled thermal-magmatic system. On the basis of recent geophysical and geochemical studies, we constrain our models to have average crustal thicknesses between 50 and 100 km that were mostly formed by 4 Ga. Our nominal model is an attempt to satisfy these constraints with a relatively simple set of conditions. Key elements of this model are the inclusion of the energetics of melting, a wet (weak) mantle rheology, self-consistent fractionation of heat-producing elements to the crust, and a near- chondritic abundance of those elements. The latent heat of melting mantle material is a small (percent level) contributor to the total planetary energy budget over 4.5 Gyr but is crucial for constraining the thermal and magmatic history of Mars. Our nominal model predicts an average crustal thickness of 62 km that was 73% emplaced by 4 Ga. -
Ocean Basin Bathymetry & Plate Tectonics
13 September 2018 MAR 110 HW- 3: - OP & PT 1 Homework #3 Ocean Basin Bathymetry & Plate Tectonics 3-1. THE OCEAN BASIN The world’s oceans cover 72% of the Earth’s surface. The bathymetry (depth distribution) of the interconnected ocean basins has been sculpted by the process known as plate tectonics. For example, the bathymetric profile (or cross-section) of the North Atlantic Ocean basin in Figure 3- 1 has many features of a typical ocean basins which is bordered by a continental margin at the ocean’s edge. Starting at the coast, there is a slight deepening of the sea floor as we cross the continental shelf. At the shelf break, the sea floor plunges more steeply down the continental slope; which transitions into the less steep continental rise; which itself transitions into the relatively flat abyssal plain. The continental shelf is the seaward edge of the continent - extending from the beach to the shelf break, with typical depths ranging from 130 m to 200 m. The seafloor of the continental shelf is gently sloping with undulating surfaces - sometimes interrupted by hills and valleys (see Figure 3- 2). Sediments - derived from the weathering of the continental mountain rocks - are delivered by rivers to the continental shelf and beyond. Over wide continental shelves, the sea floor slopes are 1° to 2°, which is virtually flat. Over narrower continental shelves, the sea floor slopes are somewhat steeper. The continental slope connects the continental shelf to the deep ocean with typical depths of 2 to 3 km. While the bottom slope of a typical continental slope region appears steep in the 13 September 2018 MAR 110 HW- 3: - OP & PT 2 vertically-exaggerated valleys pictured (see Figure 3-2), they are typically quite gentle with modest angles of only 4° to 6°. -
Tsunami Risk Analysis of the East Coast of the United States
Tsunami Risk Analysis of the East Coast of the United States INTRODUCTION METHODOLOGY In the wake of the 2004 Indian Ocean tsunami and the 2011 Japan tsunami and Given the large area of the east coast, a rudimentary analysis was performed. corresponding nuclear disaster, much more attention has been focused on coastal Elevation is the most important factor in analyzing the risk of flooding in a coastal vulnerability to tsunamis. Areas near active tectonic margins have a much higher area; the lower the elevation, the greater the potential for damage. Elevation data risk of being hit by a tsunami, due to proximity. People who live in these areas are was reclassified into no risk, medium risk, and high risk zones. These zones were: more aware of the danger than their counterparts on passive tectonic margins. It is 25+ m above sea level, 10 to 25 m above sea level, and below 10 m above sea lev- generally a good assumption that the risk of a tsunami is low in places like the el. Essentially, most land adjacent to the coast that falls in the final category eastern seaboard of the United States. would be badly damaged by a 10m tsunami from the Canary Islands, unless buff- Despite the low risk, the east coast has been hit by tsunamis in the past. Ex- ered by another portion of land blocking the coast. If a larger tsunami were to oc- amples include the Newfoundland tsunami caused by the Grand Banks earth- cur, up to the max wave height predicted by Ward and Day of 25 m, any land ad- quake. -
Coupled Onshore Erosion and Offshore Sediment Loading As Causes of Lower Crust Flow on the Margins of South China Sea Peter D
Clift Geosci. Lett. (2015) 2:13 DOI 10.1186/s40562-015-0029-9 REVIEW Open Access Coupled onshore erosion and offshore sediment loading as causes of lower crust flow on the margins of South China Sea Peter D. Clift1,2* Abstract Hot, thick continental crust is susceptible to ductile flow within the middle and lower crust where quartz controls mechanical behavior. Reconstruction of subsidence in several sedimentary basins around the South China Sea, most notably the Baiyun Sag, suggests that accelerated phases of basement subsidence are associated with phases of fast erosion onshore and deposition of thick sediments offshore. Working together these two processes induce pressure gradients that drive flow of the ductile crust from offshore towards the continental interior after the end of active extension, partly reversing the flow that occurs during continental breakup. This has the effect of thinning the continental crust under super-deep basins along these continental margins after active extension has finished. This is a newly recognized form of climate-tectonic coupling, similar to that recognized in orogenic belts, especially the Himalaya. Climatically modulated surface processes, especially involving the monsoon in Southeast Asia, affects the crustal structure offshore passive margins, resulting in these “load-flow basins”. This further suggests that reorganiza- tion of continental drainage systems may also have a role in governing margin structure. If some crustal thinning occurs after the end of active extension this has implications for the thermal history of hydrocarbon-bearing basins throughout the area where application of classical models results in over predictions of heatflow based on observed accommodation space. -
D6 Lithosphere, Asthenosphere, Mesosphere
200 Chapter d FAMILIAR WORLD The Present is the Key to the Past: HUGH RANCE d6 Lithosphere, asthenosphere, mesosphere < plastic zone > The terms lithosphere and asthenosphere stem from Joseph Barell’s 1914-15 papers on isostasy, entitled The Strength of the Earth's Crust, in the Journal of Geology.1 In the 1960s, seismic studies revealed a zone of rock weakness worldwide near the top of the upper part of the mantle. This zone of weakness is called the asthenosphere (Gk. asthenes, weak). The asthenosphere turned out to be of revolutionary significance for historical geology (see Topic d7, plate tectonic theory). Within the asthenosphere, rock behaves plastically at rates of deformation measured in cm/yr over lineal distances of thousands of kilometers. Above the asthenosphere, at the same rate of deformation, rock behaves elastically and, being brittle, it can break (fault). The shell of rock above the asthenosphere is called the lithosphere (Gk. lithos, stone). The lithosphere as its name implies is more rigid than the asthenosphere. It is important to remember that the names crust and lithosphere are not synonyms. The crust, the upper part of the lithosphere, is continental rock (granitic) in some places and is oceanic rock (basaltic) elsewhere. The lower part of lithosphere is mantle rock (peridotite); cooler but of like composition to the asthenosphere. The asthenosphere’s top (Figure d6.1) has an average depth of 95 km worldwide below 70+ million year old oceanic lithosphere.2 It shallows below oceanic rises to near seafloor at oceanic ridge crests. The rigidity difference between the lithosphere and the asthenosphere exists because downward through the asthenosphere, the weakening effect of increasing temperature exceeds the strengthening effect of increasing pressure. -
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. -
INTERIOR of the EARTH / an El/EMEI^TARY Xdescrrpntion
N \ N I 1i/ / ' /' \ \ 1/ / / s v N N I ' / ' f , / X GEOLOGICAL SURVEY CIRCULAR 532 / N X \ i INTERIOR OF THE EARTH / AN El/EMEI^TARY xDESCRrPNTION The Interior of the Earth An Elementary Description By Eugene C. Robertson GEOLOGICAL SURVEY CIRCULAR 532 Washington 1966 United States Department of the Interior CECIL D. ANDRUS, Secretary Geological Survey H. William Menard, Director First printing 1966 Second printing 1967 Third printing 1969 Fourth printing 1970 Fifth printing 1972 Sixth printing 1976 Seventh printing 1980 Free on application to Branch of Distribution, U.S. Geological Survey 1200 South Eads Street, Arlington, VA 22202 CONTENTS Page Abstract ......................................................... 1 Introduction ..................................................... 1 Surface observations .............................................. 1 Openings underground in various rocks .......................... 2 Diamond pipes and salt domes .................................. 3 The crust ............................................... f ........ 4 Earthquakes and the earth's crust ............................... 4 Oceanic and continental crust .................................. 5 The mantle ...................................................... 7 The core ......................................................... 8 Earth and moon .................................................. 9 Questions and answers ............................................. 9 Suggested reading ................................................ 10 ILLUSTRATIONS -
The Earth's Crust Is Like the Skin of an Apple
The Earth’s Crust Weathering & Erosion ! " Soil begins with rocks – so how is rock turned into soil? ! " How does soil travel and move? ! " Without sediments our planet would decline, perhaps ceasing to exist Inside the Earth The Earth's Crust is like the skin of an apple. It is very thin in comparison to the other three layers. The crust is only about 3-5 miles (8 kilometers) thick under the oceans(oceanic crust) and about 25 miles (32 kilometers) thick under the continents (continental crust). The temperatures of the crust vary from air temperature on top to about 1600 degrees Fahrenheit (870 degrees Celcius) in the deepest parts of the crust Three Laws of Thermodynamics ! " The first law of thermodynamics, also called conservation of energy, states that the total amount of energy in the universe is constant. This means that all of the energy has to end up somewhere, either in the original form or in a different from. We can use this knowledge to determine the amount of energy in a system, the amount lost as waste heat, and the efficiency of the system. ! " The second law of thermodynamics states that the disorder in the universe always increases. After cleaning your room, it always has a tendency to become messy again. This is a result of the second law. As the disorder in the universe increases, the energy is transformed into less usable forms. Thus, the efficiency of any process will always be less than 100%. ! " The third law of thermodynamics tells us that all molecular movement stops at a temperature we call absolute zero, or 0 Kelvin (-273oC). -
Asthenosphere–Lithospheric Mantle Interaction in an Extensional Regime
Chemical Geology 233 (2006) 309–327 www.elsevier.com/locate/chemgeo Asthenosphere–lithospheric mantle interaction in an extensional regime: Implication from the geochemistry of Cenozoic basalts from Taihang Mountains, North China Craton ⁎ Yan-Jie Tang , Hong-Fu Zhang, Ji-Feng Ying State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, P.O. Box 9825, Beijing 100029, PR China Received 25 July 2005; received in revised form 27 March 2006; accepted 30 March 2006 Abstract Compositions of Cenozoic basalts from the Fansi (26.3–24.3 Ma), Xiyang–Pingding (7.9–7.3 Ma) and Zuoquan (∼5.6 Ma) volcanic fields in the Taihang Mountains provide insight into the nature of their mantle sources and evidence for asthenosphere– lithospheric mantle interaction beneath the North China Craton. These basalts are mainly alkaline (SiO2 =44–50 wt.%, Na2O+ K2O=3.9–6.0 wt.%) and have OIB-like characteristics, as shown in trace element distribution patterns, incompatible elemental (Ba/Nb=6–22, La/Nb=0.5–1.0, Ce/Pb=15–30, Nb/U=29–50) and isotopic ratios (87Sr/86Sr=0.7038–0.7054, 143Nd/ 144 Nd=0.5124–0.5129). Based on TiO2 contents, the Fansi lavas can be classified into two groups: high-Ti and low-Ti. The Fansi high-Ti and Xiyang–Pingding basalts were dominantly derived from an asthenospheric source, while the Zuoquan and Fansi low-Ti basalts show isotopic imprints (higher 87Sr/86Sr and lower 143Nd/144Nd ratios) compatible with some contributions of sub- continental lithospheric mantle. The variation in geochemical compositions of these basalts resulted from the low degree partial melting of asthenosphere and the interaction of asthenosphere-derived magma with old heterogeneous lithospheric mantle in an extensional regime, possibly related to the far effect of the India–Eurasia collision. -
Tectonics and Crustal Evolution
Tectonics and crustal evolution Chris J. Hawkesworth, Department of Earth Sciences, University peaks and troughs of ages. Much of it has focused discussion on of Bristol, Wills Memorial Building, Queens Road, Bristol BS8 1RJ, the extent to which the generation and evolution of Earth’s crust is UK; and Department of Earth Sciences, University of St. Andrews, driven by deep-seated processes, such as mantle plumes, or is North Street, St. Andrews KY16 9AL, UK, c.j.hawkesworth@bristol primarily in response to plate tectonic processes that dominate at .ac.uk; Peter A. Cawood, Department of Earth Sciences, University relatively shallow levels. of St. Andrews, North Street, St. Andrews KY16 9AL, UK; and Bruno The cyclical nature of the geological record has been recog- Dhuime, Department of Earth Sciences, University of Bristol, Wills nized since James Hutton noted in the eighteenth century that Memorial Building, Queens Road, Bristol BS8 1RJ, UK even the oldest rocks are made up of “materials furnished from the ruins of former continents” (Hutton, 1785). The history of ABSTRACT the continental crust, at least since the end of the Archean, is marked by geological cycles that on different scales include those The continental crust is the archive of Earth’s history. Its rock shaped by individual mountain building events, and by the units record events that are heterogeneous in time with distinctive cyclic development and dispersal of supercontinents in response peaks and troughs of ages for igneous crystallization, metamor- to plate tectonics (Nance et al., 2014, and references therein). phism, continental margins, and mineralization. This temporal Successive cycles may have different features, reflecting in part distribution is argued largely to reflect the different preservation the cooling of the earth and the changing nature of the litho- potential of rocks generated in different tectonic settings, rather sphere.