The Plate Theory for Volcanism
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Year 7 Mastery Booklet
YEAR 7 MASTERY BOOKLET Unit 2 – Terrifying Tectonics 2019-2020 ARK CURRICLUM PROJECT Unit 2: Terrifying Tectonics What will I be learning this unit? By the end of this unit you will know all about earthquakes and volcanoes – what causes them and their impacts. You will investigate two case studies and will make an important decision about reducing future risks. Lesson 1: What is happening beneath our feet? In this lesson we learn to describe the structure of the earth and to compare its layers. Lesson 2: Why are the plates moving? In this lesson we learn how convection currents are formed and how this causes tectonic plate movement. We will use global maps to identify the main tectonic plates. Lesson 3: What are tectonic hazards and where do they occur? In this lesson we will learn to describe the global distribution of earthquakes and volcanoes, using continents and compass directions. We will also begin to understand the connection between plate boundaries and tectonic hazard distribution. Lesson 4: What causes an earthquake? In this lesson we will solve the mystery of why an earthquake happened in Sichuan in 2008 using a series of clues related to physical features and tectonic processes. Lesson 5: What were the impacts of the 2008 earthquake at Sichuan? In this lesson we are learning to describe and categorise the impacts of the 2008 Sichuan earthquake. We will start to explain why the effects were very severe. Lesson 6: What causes a volcano? In this lesson we are learning why volcanoes form at destructive plate boundaries using the case study of Volcán de Fuego in Guatemala. -
F Makwara (PDF)
CHROMITE GEOLOGY OF ZIMBABWE AND RELATED MINING CHALLENGES PRESENTATION GREAT DYKE : MUTORASHANGA AUGUST 2017 2 WORLD CHROME RESOURCE Estimate World Chromite Resource : +-12 Billion Tonnes • South Africa : 72% of world Resource - Stratiform • Zimbabwe: 12% -Stratiform & podiform • Kazakhstan: 4% - Podiform • Finland : 2% -Podiform • India : 1% -Podiform • Turkey and others : 9% -Largely podiform But Zimbabwe companies producing at full capacity is not in the top 5 producing companies . STRATIFORM & PODIFORM GEOLOGY LOCATION GEOLOGY MAP - ZIMBABWE MASHONALAND CENTRAL MASHONALAND WEST CHIRUMANZU MIDLANDS MASVINGO MBERENGWA 5 LOCATION OF STRATIFORM CHROMITE RESOURCE • Mashonaland Central: North Dyke Tengenenge Impinge Birkdale Mutorashanga • Mashonaland West: Middle Dyke Ngezi Darwendale Maryland Lembe/Mapinga Mutorashanga • Midlands: South Dyke Lalapanzi Mapanzure Bannockburn CSC LOCATION OF PODIFORM CHROMITE RESOURCES • Midlands: Valley Nhema Chirumanzu Mberengwa • Masvingo: Mashava THE GREAT DYKE AND PODIFORMS GEOLOGY • THE GREAT DYKE • Tengenenge to Mberengwa, Location • Stretches for 550km and is 4-11km wide. • PODIFORM • Isolated chrome resources in Shurugwi,Mashava ,Nhema ,Valley, Chirumanzu and Mberengwa • THE DYKE : STRATIFORM • Chromite hosts rocks are :Harzburgite, dunite, serpentinite and pyroxenite Host Rock • PODIFORM • Chromite host rocks are: Serpentinite ,Silicified Talc Carbonate and Talc Carbonate • 10 known seams, The 11 th seam is poorly exposed in the North Dyke • 8cm to 40cm thickness Chrome Seams • Average vertical spacing of seams is 30-40m • Geotechnical Parameters considered fore seams are: Seam Widths, quality, dip, friability, & continuity • Platinum Group Metals Known Minerals in • Chrome the Dyke • Asbestos • Nickel 8 CHROMITE RESOURCES • The dyke intruded as an ultramafic sill ,estimated age 2.7 Ga . STRATIFORM • 11 seams are known to exist on the Great Dyke, but not evenly distributed through out the dyke. -
Mining Within Zimbabwe's Great Dyke: Extent , Impacts & Opportunities
Mining Within Zimbabwe’s Great Dyke: Extent , Impacts & Opportunities Authors: Gilbert Makore & Veronica Zano Published by: Zimbabwe Environmental Law Association (ZELA) Sponsored by: International Alliance on Natural Resource in Africa (IANRA) Authors: Gilbert Makore and Veronica Zano Editor: Muduso Dhliwayo Copyright: 2012. Zimbabwe Environmental Law Association (ZELA) This publication may be reproduced in whole or in part and in any form for educational or non-profit uses, without special permission from the copyright holder, provided full acknowledgement of the source is made. No use of this publication may be made for resale or other commercial purposes without the prior written permission of ZELA. Year of Publication: 2012 Available from: Zimbabwe Environmental Law Association (ZELA), No. 6 London Derry Road, Eastlea, Harare, Zimbabwe: Tel: 253381; 252093, Email: , Website: www.zela.org Zimbabwe Environmental Law Association International Alliance on Natural Resource in Africa International Alliance on Natural Resources in Africa MINING WITHIN ZIMBABWE’S GREAT DYKE: EXTENT , IMPACTS AND OPPORTUNITIES I Table of Contents Executive Summary: 1 The Great Dyke Mineral Belt: 2 Mining and Mining Development Contribution to Economic Growth: 5 Companies operating in the Great Dyke: 10 Communities along the Great Dyke: 12 Impacts of Mining on the Great Dyke Communities: 14 Recommendations: 19 Conclusion: 20 MINING WITHIN ZIMBABWE’S GREAT DYKE: EXTENT , IMPACTS AND OPPORTUNITIES ii Executive Summary The Great Dyke is a seam of ore-bearing rock that goes from the north to the south of Zimbabwe. The Dyke spans a total length of 550kms and has a maximum width of 11kms. This geological feature represents an important resource for Zimbabwe's national economy and the local communities' livelihoods. -
Different Causes of the Delamination on the Example of Caucasus and Kyrgyz Tien Shan Collision Zones
EGU2020-6412 https://doi.org/10.5194/egusphere-egu2020-6412 EGU General Assembly 2020 © Author(s) 2021. This work is distributed under the Creative Commons Attribution 4.0 License. Different causes of the delamination on the example of Caucasus and Kyrgyz Tien Shan collision zones. Irina Medved1,2,3, Ivan Koulakov2,3, and Mikhail Buslov1 1IGM SB RAS, Novosibirsk, Russian Federation ([email protected]) 2IPGG SB RAS, Novosibirsk, Russian Federation 3Novosibirsk State University, Novosibirsk, Russian Federation The causes of delamination of the mantle lithosphere in collision zones is actively debated in the scientific community. The main discussions are focused on the initiation of sinking of the continental lithosphere into the asthenosphere to a depth. Most scientists believe that such kind of immersion is impossible. However, there are several articles showing that this process is nonetheless taking place. For example Kay and Kay, (1993), Faccenda, Minelli, Gerya, (2009), Ueda et. al., (2012) and others propose various mechanisms of delamination, for example: eclogitization of the mafic layer of the lower crust, the effect of convection in the upper mantle, or gradual transition of the oceanic subduction into continental collision. Does the mantle part of the lithosphere sink into the mantle or spread laterally, as described in [for example, Deep Geodynamics, 2001; Bird, 1991; Schmeling and Marquart, 1991]? To answer these questions, we study deep structures beneath the Caucasus and Kyrgyz Tien Shan collision zones. The studies were carried out on the basis of multiscale seismic tomography methods: regional and global. This approach made it possible to study heterogeneities both in the crust and in the upper mantle. -
A Semi-Quantitative Model for the Formation of Great Dyke-Type Platinum Deposits
A Semi-Quantitative Model for the Formation of Great Dyke-Type Platinum Deposits William P. Meurer1 and Alan E. Boudreau2 1Dept. of Geosciences, Univ. of Houston, 312 Sci. & Res. Bldg. 1, Houston, TX 77204-5007 2Div. Earth Sci., Nicholas School of the Env. and Earth Sci., Box 90227, Duke University, Durham, NC 27708 email: [email protected] The uppermost parts of the ultramafic 2) The PGE-sulfide mineralization is sections of some layered intrusions host significant commonly found below the ultramafic-mafic deposits of the platinum-group elements (PGE). contact. In addition, there are typically significant The type example of this class of PGE deposit is stratigraphic “offsets” between the maximum the Great Dyke of Zimbabwe. The Munni Munni concentrations of the PGE, base metals and sulfur. deposit has a similar occurrence (e.g., Hoatson and 3) At discrete horizons, just below the Keays, 1989). In the Stillwater Complex of ultramafic-mafic boundary, the rocks have higher Montana there are local shows of PGE-sulfide incompatible trace-element concentrations, greater enrichments at the top of the Ultramafic series but modal proportions of interstitial minerals, and more they are not laterally continuous (fig. 1). evolved mineral compositions. These features are These deposits have a number of common interpreted to reflect a marked enrichment in features: crystallized interstitial liquid in these rocks. 1) Each is characterized by a lower A number of investigators have suggested sequence of ultramafic rocks consisting mainly of that these zones are the result of a complex pyroxene and olivine overlain by mafic rocks interplay of extreme fractionation, magma mixing, containing 50 to 60 % plagioclase. -
Warping and Cracking of the Pacific Plate by Thermal Contraction
1 Warping and Cracking of the Pacific Plate by Thermal Contraction David Sandwell & Yuri Fialko Scripps Institution of Oceanography, La Jolla, California, 92093-0225, USA Submitted to Journal of Geophysical Research, March 16, 2004. Lineaments in the gravity field and associated chains of volcanic ridges are widespread on the Pacific plate but are not yet explained by plate tectonics. We propose that they are warps and cracks in the plate caused by uneven thermal contraction of the cooling lithosphere. Top-down cooling of the plate produces large thermoelastic stress that is optimally released by lithospheric flexure between regularly spaced parallel cracks. Both the crack spacing and gravity amplitude are predicted by elastic plate theory and variational principle. Cracks along the troughs of the gravity lineaments provide conduits for the generation of volcanic ridges in agreement with new observations from satellite-derived gravity. Our model suggests that gravity lineaments are a natural consequence of lithospheric cooling so that convective rolls or mantle plumes are not required. Introduction Plate tectonics explains most of the topography of the deep ocean basins, but there is still debate regarding the origin of off-ridge features that are younger than the ambient lithosphere, and especially those that are not aligned with the autochtonic seafloor spreading fabric. The Pacific basin contains three main types of the young off-ridge lineaments (Figure 1). (i) Chains of shield volcanoes such as the Hawaiian-Emperor seamounts are well explained by the mantle plume model [Morgan, 1971; Sleep, 1992]. (ii) Gravity lineaments are prominent at 140-200 km wavelength and are aligned in the direction of absolute plate motion [Haxby and Wessel, 1986] (Figure 1b). -
Post-Collisional Mantle Delamination in the Dinarides Implied
www.nature.com/scientificreports OPEN Post‑collisional mantle delamination in the Dinarides implied from staircases of Oligo‑Miocene uplifted marine terraces Philipp Balling1*, Christoph Grützner1, Bruno Tomljenović2, Wim Spakman3 & Kamil Ustaszewski1 The Dinarides fold‑thrust belt on the Balkan Peninsula resulted from convergence between the Adriatic and Eurasian plates since Mid‑Jurassic times. Under the Dinarides, S‑wave receiver functions, P‑wave tomographic models, and shear‑wave splitting data show anomalously thin lithosphere overlying a short down‑fexed slab geometry. This geometry suggests a delamination of Adriatic lithosphere. Here, we link the evolution of this continental convergence system to hitherto unreported sets of extensively uplifted Oligocene–Miocene (28–17 Ma) marine terraces preserved at elevations of up to 600 m along the Dinaric coastal range. River incision on either side of the Mediterranean‑Black Sea drainage divide is comparable to the amounts of terrace uplift. The preservation of the uplifted terraces implies that the most External Dinarides did not experience substantial deformation other than surface uplift in the Neogene. These observations and the contemporaneous emplacement of igneous rocks (33–22 Ma) in the internal Dinarides suggest that the Oligo‑Miocene orogen‑wide uplift was driven by post‑break‑of delamination of the Adriatic lithospheric mantle, this was followed by isostatic readjustment of the remaining crust. Our study details how lithospheric delamination exerts an important control on crustal deformation and that its crustal signature and geomorphic imprint can be preserved for millions of years. Te infuence of deep-seated processes on deformation patterns and rates in collisional orogens is unequivo- cally accepted, yet challenging to quantify. -
UNIT 10 Plate Tectonics Study Guide
UNIT 10 Plate Tectonics Study Guide Chapters 1, 2, 9, and most of book (Revised 7/18) UNIT 10 HOMEWORK worth 10 points VIDEO WEB HIT HOMEWORK: Write two paragraphs with minimum of three sentences each (PHYSICAL GEOLOGY 1303) (Revised 7//18) UNIT 10 Video Hits For Unit 10 Video Hit, go to the “DMC HOME” website; in Search box –type “Kramer”, select “Faculty Listing”; click on Walter Vernon Kramer, click on Website“, scroll down and click GEOL 1303; then select “Video Hit Link Number 10”, and click on icon, watch video of life forms that don’t need sunlight!. [IF NONE OF THE WEB SITES COME UP, YOUR COMPUTER PROBABLY NEEDS TO BE REBOOTED (RESTARTED) General -Tectonics: the branch of geology that studies regional and global structural features on Earth -Plate tectonics: the unifying theory of global dynamics. The lithosphere is believed to be broken into individual plates that move in response to convection within the Earth’s upper mantle. -Plate tectonics theory explains the interrelationships of volcanoes, earthquakes, climate, mountains, and even evolution. Historical Studies of the Ocean Floor -Evidence for tall mountains under the Mid-Atlantic Ocean was presented in the 1850s. -The laying of the transatlantic telegraph cable 1860s proved that there was a mountain range in the middle of the Atlantic Ocean. 1850 map 1908 map FYI In 1878, Wyville Thompson compiled ocean depth data from the scientific sailing ship (the HMS Challenger) and collected samples of rock (basalt) from these deep-underwater mountains. Thirty years later in 1908, this data was compiled and the results further implied an extensive mid-Atlantic mountain range (which was largely ignored). -
Suzanne Y. O'reilly, GEMOC National
controversy over the physical nature of the lithosphere and asthenosphere and the boundary zone between them. The subcontinental lithospheric mantle is isolated from the convecting mantle and thus tends to resist homogenization over time. At the lithosphere-asthenosphere boundary, the temperatures of the lithosphere and the uppermost asthenosphere coincide, and the greater buoyancy and viscosity of the lithosphere are important in maintaining its mechanical integrity. Suzanne Y. O’Reilly, GEMOC National mantle roots are highly buoyant; they This emphasizes a thermal and Key Centre, Department of Earth cannot be delaminated but require rheological distinction between and Planetary Sciences, Macquarie mechanical disaggregation (lithospheric lithosphere and asthenosphere that also University, Sydney, NSW 2109, Australia thinning and/or rifting) and infiltration coincides well with seismic observations of upwelling fertile material to be and with the geochemical signatures William L. Griffin, GEMOC National Key destroyed or transformed. In contrast, that are used in this paper to help define Centre, Department of Earth and Phanerozoic subcontinental lithospheric the location and character of the Planetary Sciences, Macquarie mantle is denser than the asthenosphere lithosphere-asthenosphere boundary. University, Sydney, NSW 2109, Australia, for observed thicknesses (~100 km) and Four-dimensional lithosphere and CSIRO Exploration and Mining, can “delaminate” under stress. The mapping is a methodology that P.O. Box 136, North Ryde, NSW 1670, contrasting properties of different integrates petrological, geochemical, Australia mantle domains require lateral contrasts geophysical, and tectonic information to in composition, density, thickness, and map the composition of the sub- Yvette H. Poudjom Djomani, GEMOC seismic response in the present-day continental lithospheric mantle (Fig. -
Plate Tectonics on Early Earth? Weighing the Paleomagnetic Evidence
spe440-12 3rd pages The Geological Society of America Special Paper 440 2008 Plate tectonics on early Earth? Weighing the paleomagnetic evidence David A.D. Evans* Department of Geology & Geophysics, Yale University, New Haven, Connecticut 06520-8109, USA Sergei A. Pisarevsky* School of GeoSciences, University of Edinburgh, Edinburgh EH9 3JW, Scotland, UK ABSTRACT Paleomagnetism is the only quantitative method available to test for lateral motions by tectonic plates across the surface of ancient Earth. Here, we present several analyses of such motions using strict quality criteria from the global paleomagnetic database of pre–800 Ma rocks. Extensive surface motion of cratons can be documented confi dently to older than ca. 2775 Ma, but considering only the most reliable Archean data, we cannot discern differential motion from true polar wander (which can also generate surface motions relative to the geomagnetic reference frame). In order to fi nd evidence for differential motions between pairs of Precambrian cratons, we compared distances between paleomagnetic poles through precisely isochronous intervals for pairs of cra- tons. The existing database yields several such comparisons with ages ranging from ca. 1110 to ca. 2775 Ma. Only one pair of these ages, 1110–1880 Ma, brackets signifi cantly different apparent polar wander path lengths between the same two cratons and thus demonstrates differential surface motions. If slightly less reliable paleomagnetic results are considered, however, the number of comparisons increases dramatically, and an example is illustrated for which a single additional pole could constrain differential cratonic motion into the earliest Paleoproterozoic and late Neoarchean (in the interval 2445–2680 Ma). -
Magnetic and Gravity Interpretation of Yaloc-69 Data from the Cocos Plate Area
AN ABSTRACT OF THE THESIS OF Richard Shih-Ming Lu for the Master of Science (Name) (Degree) in Geophysics presented on ig-il (Major) (Date) Title:MAGNETIC AND GRAVITY INTERPRETATIONOF YALOC-69 DATA FROM THE COCOS PLATE AREA Abstract approved: Redacted for Privacy Donald F. Heinrichs Magnetic, gravity and bathymetry data werecollected on an ex- tended cruise of the R/V Yaquina in 1969.The last set of data was ob- tamed from those track lines leaving thePanama Basin.The area covered is mainly the Cocos plate (Molnarand Sykes, 1969).The data is analyzed and compared with resultsof previous workers and the geophysical implications considered. Generally speaking, from the magnetic partof the data, both direct and indirect methods show supportof Vine and Matthew's (1963) hypothesis of sea-floor spreadingand the subsequent principles of new global tectonics.The most northern magnetic anomaly profile across the East Pacific rise(at 18. 3°N) shows a spreading rate about 3 cm/yr. and the most southern one(at 12. 8°N) shows a rate about 5. 2 cm/yr.The Cocos plate has been assumed to movein a northeast- southwest direction(N30°E to N45°E), and rotate with respect to the Pacific plate about a pole at40°N, 11 0°W with an angular velocity of -7 19. 6x10 deg. /yr. (Larson and Chase, 1970).New material comes up from the west boundary -the East Pacific rise, and the south boundary - the Galapogos rift, causing theCocos plate to underthrust the Americans plate at the middle American arc.Some of the points of. -
Volcanoes, Mountains 2
Earth & Space Science Packet April 6th-17th, 2020 Griffin & King This packet contains: 1. Worksheets for Earthquakes, Plate Tectonics, Volcanoes, Mountains 2. Plate Tectonics Lab 3. Volcano Lab 4. National Geographic Article on Volcanoes What needs to be turned in for a grade? ● Worksheets with questions answered (Earthquakes and Plate Tectonics is April 6-9; Volcanoes and Mountains is April 14-17) Optional/Enrichment included: ● Labs ● Science Articles If these are completed, we would LOVE for you to share: Send us pictures on remind/email, or tag @TheBurgScience and #Team DCS on Twitter Earth and Space Science students, The only assignments required from us are the worksheets included. At times we may also include a Scientific article for you to read. You can either submit them electronically or you can take a picture of your answers and send us the picture either through Remind or via email. Paper packets should be completed and “turned in” the same way – snap a picture and send it to us either via Remind or email. These are not meant to be difficult or overwhelming. We simply hope they keep your mind engaged while we try to accomplish distance learning. The labs are completely optional and only meant to help bring some of this material to life. Also, we hoped it would be something fun for you to do. We miss you all very much! We hope you are doing well and that you are staying healthy. If there is ever a time that you need help with anything during this time, please do not hesitate to let one of us know.