DOCSLIB.ORG

Influence of Foliation Fracture Systems on Water Availability in the Lawrenceville, Georgia, Area

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Influence of Foliation Fracture Systems on Water Availability in the Lawrenceville, Georgia, Area INFLUENCE OF FOLIATION FRACTURE SYSTEMS ON WATER AVAILABILITY IN THE LAWRENCEVILLE, GEORGIA, AREA Lester J. Williams AUTHOR: Hydrologist, U.S. Geological Survey, 3039 Amwiler Road, Suite 130, Peachtree Business Center, Atlanta, Georgia 30360-2824. REFERENCE: Proceedings of the 2003 Georgia Water Resources Conference, held April 23–24, 2003, at the University of Georgia. Kathryn J. Hatcher, editor, Institute of Ecology, The University of Georgia, Athens, Georgia. Abstract. The city of Lawrenceville, Georgia, development of water-producing fracture systems in the pumps ground water mainly from wells completed in a area, a study was conducted in cooperation between the system of productive fractures formed parallel to folia- U.S. Geological Survey (USGS) and the city of Law- tion and compositional layering in layered crystalline renceville (Chapman and others, 1999). In Lawrence- rocks. Much less production is obtained from planar, ville (Fig. 1), ground water is derived almost exclu- more steeply dipping joints intersecting boreholes. The sively from high-yielding “foliation fractures,” which combination of subhorizontal sets of foliation fractures are recharged from the overlying regolith. This paper and a well-developed network of steeply dipping joints describes lithologic and structural controls on the de- that connect these fractures to regolith source water velopment of water-bearing foliation-fracture systems creates a fracture system that can sustain large well and presents a conceptual model of ground-water avail- yields ranging from 100 to 400 gallons per minute ability based on geologic and hydrologic data that were (gal/min). Joints and joint sets generally are low yield- collected as part of the cooperative study. ing and produce water ranging from 1 to 5 gal/min, and 84° 84°56' in few cases as high as 30 to 35 gal/min where the joint 34° opening is created from dissolution of a pre-existing mineral infilling. Fractures formed from weathering 14FF59 along foliation planes yield water ranging from 1 to 15 14FF58 14FF42 Maltbie gal/min for individual foliation partings and ranging 13FF15 Street 14FF52 wells from 50 to 100 gal/min for larger openings. The model 14FF46 13FF12 13FF20 13FF16 14FF49 14FF10 13FF14 14FF08 14FF16 presented in this paper indicates that a “weathering 14FF50 13FF18 13FF13 14FF27 13FF17 ?14FF56 wedge” or a zone of weathered rock either originates Rhodes 14FF55 Jordan 14FF53 13FF22 from the outcrop area or develops from steeply dipping 13FF21 14FF47Well field joint systems transmitting water into the bedrock, or a 13FF23 LAWRENCEVILLE combination of these two. Once a ground-water flow 33°56' 13FF19 path is established, progressive differential weathering along foliation planes and layering forms zones of in- 14FF57 0 0.5 1 MILE creased bedrock permeability. Where foliation fracture systems dominate the flow system, this model could be 0 0.5 1 KILOMETER Base modified from Chapman used to better understand ground-water availability and and others, 1999 EXPLANATION recharge to bedrock. Rock type Amphibolite Biotite gneiss INTRODUCTION Lawrenceville Button schist Crystalline rock aquifers in the Piedmont physi- Quartzite-schist Granite gneiss ographic province have the potential for supplying large Diabase amounts of potable water for supplemental, or sole- Synform source supply to small communities in areas of in- Well—Filled circle, creased bedrock permeability. Use of these aquifers is yield of 100 gallons limited mainly because of the poor understanding of the per minute or more fracture systems that convey water to wells. To deter- Figure 1. Geologic map of the Lawrenceville area showing mine specific lithologic and structural controls on the lithologic units and large-scale geologic features. Method of Study Foliation fractures appear to provide the largest During the study, emphasis was placed on develop- yields to bedrock wells in the Lawrenceville area, with ing a relation between the lithology mapped at land sur- some of the larger fractures yielding as much as several face and subsurface fractures, so that surface-mapping hundred gallons per minute (gal/min). Individual data could be more readily used to develop ground-water foliation partings yield water in the 1- to 15-gal/min resources in the Piedmont region. Detailed surface geo- range and in a few cases more than 30 gal/min, logic mapping was conducted to define major lithologic compared to a range of 1 to 5 gal/min for open water- units and structural controls. To define the characteristics bearing joints. The difference in yield between foliation of water-bearing fractures, borehole geophysical logs fractures and joints likely is because most of the were collected in 32 bedrock wells and pumping tests foliation fractures are formed along relatively flat-lying were conducted in 10 wells. The depth and nature of frac- lithologic units that extend along contact zones and tap ture openings were determined mainly from optical and into numerous steeply dipping joints and joint sets. acoustic televiewer logs and downhole camera surveys. Hence, the foliation fractures connect a large network Yield from individual fractures or fracture zones was of steeply dipping joints and have the capacity to estimated by correlating increases in yield recorded dur- transmit large amounts of water into open boreholes. ing drilling, to the measured depths of the water-bearing The presence of at least one large fracture between fractures. Individual fracture yield was confirmed in se- foliation planes or compositional layers seems neces- lected wells using flow-meter surveys and packer testing. sary to produce well yields of greater than 50 gal/min. Conversely, the scarcity or even absence of joints in the FOLIATION-FRACTURE SYSTEMS bedrock does not always preclude high well yields. For example, wells penetrating the amphibolite mass west Using borehole imaging data and correlating these of Lawrenceville (Fig. 1) yield water, almost exclu- data to individual fracture yield, two main systems of sively, from foliation and compositional layering frac- water-bearing fractures were observed in the Law- tures. In wells in this area, joints are relatively scarce renceville area: (1) openings along foliation planes and and are not water bearing, except for one well where layering, which make up a system of discontinuous, but several open joints were observed. high-yielding, fractures (termed foliation fractures herein); and (2) zones of intense jointing and open Influence of Lithology joints, which make up a series of mostly steeply dip- Lithology strongly controls the occurrence and ping low-yielding fractures. Water-bearing fractures distribution of fractures near Lawrenceville. On a bore- also occur as a result of dissolution of pre-existing hole scale, lithologic control was directly observed by crosscutting mineralized joints, which create irregular the presence of fracture openings at lithologic contacts openings that cross foliation and layering. in multilayered rocks or at contacts between major Foliation-fracture systems are comprised of discrete lithologic units, confirming earlier observations made fractures formed along bedrock foliation and layering. by Cressler and others, (1983) and Herrick and Legrand Although these fractures are not continuous throughout (1949). At the outcrop scale, productive foliation the area, they appear to be developed along large-scale fractures appear to be limited to, and form along the geologic features (such as pervasive or extensive folia- strike of layered rocks consisting mostly of amphi- tion or folds); and, thus, their extent may be estimated bolite, biotite gneiss, and button schist (Fig. 1). The if geologic structure and lithology are mapped. Indi- discontinuous nature of foliation fractures probably is vidual fractures within the foliation-fracture system controlled by the weathering characteristics of range from partial openings to foliation partings, to individual layers in the bedrock. Along strike, lithologic large water-bearing foliation fractures with apertures as units have compositional and textural changes that also large as 10 to 12 inches. In many cases, the foliation lead to differences in the weathering characteristics and fracture at its point of intersection with the well bore the depth and degree to which these fractures are has a variable aperture that conforms to undulatory fo- developed. The feldspar-dominant biotite gneiss is liation planes in the rock. This indicates that fractures particularly susceptible to deep weathering. Foliation of this type probably are undulatory and thicken and fractures were not observed in boreholes penetrating thin along their length. Wells that penetrate foliation massive, weakly foliated rocks, such as granite gneiss fracture systems derive water from single to multiple (Fig. 1). The granite gneiss is quartz rich, making this dominant fractures to groups of water-bearing foliation rock type less prone to differential weathering. partings along weathered bedrock zones. Lithology also affects mechanical properties that, in Recharge Evapotranspiration turn, control the degree of jointing from post-meta- Runoff REGOLITH Stream morphic brittle deformation. Ductile lithologies, such Outcrop area as the button schist unit, exhibit less abundant jointing Ground- in outcrops than do the brittle rocks because of their water flow Contact ability to absorb more strain; conversely, more brittle lithologies (such as quartzite) exhibit abundant jointing. In layered rocks,
Load more

Recommended publications
  • Metamorphic Rocks.Pdf
    Metamorphism & Metamorphic Rocks (((adapted from Brunkel, 2012) Metamorphic Rocks . Changed rocks- with heat and pressure . But not melted . Change in the solid state . Textural changes (always) . Mineralogy changes (usually) Metamorphism . The mineral changes that transform a parent rock to into a new metamorphic rock by exposure to heat, stress, and fluids unlike those in which the parent rock formed. granite gneiss Geothermal gradient Types of Metamorphism . Contact metamorphism – – Happens in wall rock next to intrusions – HEAT is main metamorphic agent . Contact metamorphism Contact Metamorphism . Local- Usually a zone only a few meters wide . Heat from plutons intruded into “cooler” country rock . Usually forms nonfoliated rocks Types of Metamorphism . Hydrothermal metamorphism – – Happens along fracture conduits – HOT FLUIDS are main metamorphic agent Types of Metamorphism . Regional metamorphism – – Happens during mountain building – Most significant type – STRESS associated with plate convergence & – HEAT associated with burial (geothermal gradient) are main metamorphic agents . Contact metamorphism . Hydrothermal metamorphism . Regional metamorphism . Wide range of pressure and temperature conditions across a large area regional hot springs hydrothermal contact . Regional metamorphism Other types of Metamorphism . Burial . Fault zones . Impact metamorphism Tektites Metamorphism and Plate Tectonics . Fault zone metamorphism . Mélange- chaotic mixture of materials that have been crumpled together Stress (pressure) . From burial
    [Show full text]
  • The Initiation and Development of Metamorphic Foliation in the Otago Schist, Part 2: Evidence from Quartz Grain-Shape Data
    The initiation and development of metamorphic foliation in the Otago Schist, Part 2: Evidence from quartz grain-shape data AARON STALLARD,1 DAVID SHELLEY1 AND STEVE REDDY2 1Department of Geological Sciences, University of Canterbury, Private Bag 4800, Christchurch, New Zealand ([email protected]) 2Tectonics Special Research Centre, Dept. of Applied Geology, Curtin University of Technology, Perth, WA 6845, Australia ABSTRACT Shape, size and orientation measurements of quartz grains sampled along two transects that cross zones of increasing metamorphic grade in the Otago Schist, New Zealand, reveal the role of quartz in the progressive development of metamorphic foliation. Sedimentary compaction and diagenesis contributed little to forming a shape preferred orientation (SPO) within the analysed samples. Metamorphic foliation was initiated at sub-greenschist facies conditions as part of a composite S1- bedding structure parallel to the axial planes of tight to isoclinal F1 folds. An important component of this foliation is a pronounced quartz SPO that formed dominantly by the effect of dissolution- precipitation creep on detrital grains in association with F1 strain. With increasing grade, the following trends are evident from the SPO data: (i) a progressive increase in the aspect ratio of grains in sections parallel to lineation, and the development of blade-shaped grains; (ii) the early development of a strong shape preferred orientation so that blade lengths define the linear aspect of the foliation (lineation) and the intermediate axes of the blades define a partial girdle about the lineation; (iii) a slight thinning and reduction in volume of grains in the one transect; (iv) an actual increase in thickness and volume in the survivor grains of the second transect.
    [Show full text]
  • Lab 5: Textures and Identification of Metamorphic Rocks
    LAB 5: TEXTURES AND IDENTIFICATION OF METAMORPHIC ROCKS OBJECTIVES: 1) to become familiar with textures characteristic of metamorphic rocks; 2) to become familiar with properties important in recognizing and classifying metamorphic rocks; 3) to become familiar with the mineralogy of common metamorphic rocks. INTRODUCTION: Metamorphic rocks are formed from pre-existing rocks by recrystallization in the solid state under the effects of heat, pressure, shearing (grinding), or replacement by materials (ions) dissolved in water. They are classified on the basis of texture (foliated vs. non-foliated), grain-size, and mineral composition. Texture: Metamorphic rocks may have either foliated (layered) or non-foliated texture. Foliated texture is a pervasive layering caused by compositional layering or by the parallel orientation of platy (e.g, mica) or elongate (e.g., amphibole) mineral grains. Foliation is caused by recrystallization under directed (compressional) stress. However, if the rock lacks platy or elongate minerals, it will not develop foliation even though it recrystallized under very great pressure (examples are marble and quartzite). Grain size: Grain size reflects pressure and temperature conditions of metamorphism. Generally, higher temperatures and pressures (higher grades of metamorphism) favor larger grains, and lower temperatures and pressures favor smaller grains. Mineral composition: Mineral composition reflects the composition of the parent rock and the pressure and temperature conditions under which the metamorphism occurred. See Marshak p. 241-244 for discussion of metamorphic grades and for the index minerals used to identify them. Classification: Foliated metamorphic rocks: Grain size is the main basis for classification of foliated metamorphic rocks. Slates are very fine-grained, well-foliated (very well-layered) rocks.
    [Show full text]
  • Review Our Ni 43-101 Technical Report Here
    Titan Gold Property Form 43-101F1 Technical Report June 2020 TECHNICAL REPORT On the Titan Gold Property Klotz Lake Area, NTS Map 42F Thunder Bay Mining District Northwestern Ontario, Canada Prepared for: SOLDERA MINING CORP. 6th Floor 905 West Pender Street Vancouver, BC V6C 1L6 Prepared by: Martin Ethier, P.Geo. Consulting Geologist Hinterland Geoscience and Geomatics 620 Brewster Street. Haileybury, Ontario P0J 1K0 June 12, 2020 (Effective Date: June 12, 2020) 1 | P a g e Titan Gold Property Form 43-101F1 Technical Report June 2020 TABLE OF CONTENTS 1.0 SUMMARY ............................................................................................................... 6 2.0 INTRODUCTION ..................................................................................................... 10 2.1 Purpose of Report ............................................................................................. 10 2.2 Sources of Information ..................................................................................... 10 3.0 RELIANCE ON OTHER EXPERTS .............................................................................. 10 4.0 PROPERTY DESCRIPTION AND LOCATION ............................................................. 11 5.0 ACCESS, CLIMATE, PHYSIOGRAPHY, LOCAL RESOURCES, AND INFRASTRUCTURE 17 5.1 Access ................................................................................................................ 17 5.2 Climate .............................................................................................................
    [Show full text]
  • Squeezing Blood from a Stone: Inferences Into the Life and Depositional Environments of the Early Archaean
    Squeezing Blood From A Stone: Inferences Into The Life and Depositional Environments Of The Early Archaean Jelte Harnmeijer A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy University of Washington MMX Programs Authorized to Offer Degree: Center for Astrobiology & Early Earth Evolution and Department of Earth & Space Sciences Abstract A limited, fragmentary and altered sedimentary rock record has allowed few constraints to be placed on a possible Early Archaean biosphere, likewise on attendant environmental conditions. This study reports discoveries from three Early Archaean terrains that, taken together, suggest that a diverse biosphere was already well- established by at least ~3.5 Ga, with autotrophic carbon fixation posing the most likely explanation for slightly older 3.7 - 3.8 Ga graphite. Chapter 2 aims to give a brief overview of Early Archaean geology, with special reference to the Pilbara’s Pilgangoora Belt, and biogeochemical cycling, with special reference to banded-iron formation. Chapter 3 reports on the modelled behaviour of abiotic carbon in geological systems, where it is concluded that fractionations incurred through autotrophic biosynthesis are generally out of the reach of equilibrium processes in the crust. In Chapter 4, geological and geochemical arguments are used to identify a mixed provenance for a recently discovered 3.7 - 3.8 Ga graphite-bearing meta-turbidite succession from the Isua Supracrustal Belt in southwest Greenland. In Chapter 5 and 6, similar tools are used to examine a newly discovered 3.52 Ga kerogenous and variably dolomitized magnetite-calcite meta- sediment from the Coonterunah Subgroup at the base of the Pilbara Supergroup in northwest Australia.
    [Show full text]
  • Geometry and Deformation History of Mylonitic Rocks and Silicified Zones Along the Mesozoic Connecticut Valley Border Fault, Western Massachusetts
    ALUN MASS/AMHERST ‘ 31206600765055e fi A ed ‘ : . te a ‘ : Rea A) ll Od ir Ler yie 5 : ‘ 5 3 : $iifaedst! * ‘ 1 5 me ah a - aor peel segs oS rt shay nyt 1 . : Sybey see Patil Pr ae CEs a os ey ee , Ste ee nts yee ee Tp sl pa) seat D Bataade ee . {FM ave ay og : 5 jos atrs DeVere ns era See) ; Lyesverr POET d ’ i oy Verereiaihey ' . hous : Pathak heche u) PE oS Dalle ene ot a eae it) pica Cris MoM te ELA MLA die 3 LE GEE Ad Ch APTN ORE FEV EE AYO AY AE k par ‘ Date Mowe : : sere (no, phe ey Teast ahd ¢ ity a 23% .4% Ay ts eater ee) pa To Pe Ste ophgraeaiek sdpre aay arena ' Pig by ’ ‘ ‘ yee vere Sry on Fic $e x bdalld cet antec Feb Ata eno ae PUTSNT tet W ee SANTEE eT VOTRE ey J Gf, sees 5 ’ ; . ty : ‘ : 4 DSC LE ih DR Jat SOK AT CR Ra gir al Ao Id, eval tat WC SORES caer y Et poy asses ist dre sg ety" : hie Fis bi : u ; y erie } he 5 wie UPD SO ata th Puede? Lae an to Peres) Gee ems i ar aac rn a neha dyhatype aT aint Spark ey sap ea ee tial petty GUS hstghe Vecye peponeagon ererervet Tp aig paar ” gieteMewner F Phe : reba S : rypiech, : ‘ Oh oll lac ah lil tet nt octane stare? re ee eee a eee ry ' tas 7 : ep oy gk bil an i ‘ nea Ay ce iC ie : ' : : ae ' oe arch ire? es rk .
    [Show full text]
  • Ironstones of Mixed Sedimentary and Hydrothermal Origin in the Archean Greenstone Belt at Bird Lake, Manitoba
    Fluid-Mineral Interactions: A Tribute to H. P. Eugster © The Geochemical Society, Special Publication No.2, 1990 Editors: R. J. Spencer and l-Ming Chou Ironstones of mixed sedimentary and hydrothermal origin in the Archean greenstone belt at Bird Lake, Manitoba ALLAN C. TURNOCK and DAVID L. TRUEMAN* Department of Geological Sciences, University of Manitoba, Winnipeg R3T 2N2, Canada Abstract-This paper describes the forms and associations of aluminous ironstones in volcaniclastic comglomerates in a zone of proximal felsic volcanism, and from 14 bulk rock analyses and element correlations we assign Fe, Mn, Mg, Ca, to a chemical precipitate-exhalative origin, AI, Zr, K, Rb, Si, to a clastic felsite origin, alkali losses to hydrothermal leaching, and variable Ti, Cu, Zn, Mo, Co, V, to unexplained diagenesis. Iron formations of three facies, chert banded silicate, sulfide ironstone, and aluminous ironstones, are found in an area 1 X 2 km of "Algoma-type" association, with clastic sedimentary rocks and felsic volcanics. The aluminous ironstones contain iron (as FeO) 16 to 47 wt%. They are garnet + cummingtonite + biotite + hornblende as staurolite-grade metamorphic minerals. They occur as (I) beds and lenses 2 to 60 em thick, I to 30 m long, interbedded in conglomerates; (2) matrix in bimodal conglomerates, i.e. mafic matrix to felsite fragments. The mafic matrix has a patchy distribution in conglomerates which have felsic fragments and felsic matrix; (3) filling fractures in a dome ofQFP (quartz-felspar- porphyry), that has intruded explosively into the floor of the basin, and, (4) veins (rare) that cut across psammitic beds in the area at the flank of the QFP dome.
    [Show full text]
  • USBR Engineering Geology Field Manual Volume 1 Chapter 5
    Chapter 5 TERMINOLOGY AND DESCRIPTIONS FOR DISCONTINUITIES General Structural breaks or discontinuities generally control the mechanical behavior of rock masses. In most rock masses the discontinuities form planes of weakness or surfaces of separation, including foliation and bedding joints, joints, fractures, and zones of crushing or shearing. These discontinuities usually control the strength, deformation, and permeability of rock masses. Most engineering problems relate to discontinuities rather than to rock type or intact rock strength. Discontinuities must be carefully and adequately described. This chapter describes terminology, indexes, qualitative and quantitative descriptive criteria, and format for describing discontinuities. Many of the criteria contained in this chapter are similar to criteria used in other established sources which are accepted as international standards (for example, International Journal of Rock Mechanics, 1978 [1]). Discontinuity Terminology The use of quantitative and qualitative descriptors requires that what is being described be clearly identified. Nomenclature associated with structural breaks in geologic materials is frequently misunderstood. For example, bedding, bedding planes, bedding plane partings, bedding separations, and bedding joints may have been used to identify similar or distinctly different geological features. The terminology for discontinuities which is presented in this chapter should be used uniformly for all geology programs. Additional definitions for various types of discontinuities are presented in the Glossary of Geology [2]; these may be used to further describe structural breaks. The following basic defi- nitions should not be modified unless clearly justified, and defined. FIELD MANUAL Discontinuity.—A collective term used for all structural breaks in geologic materials which usually have zero to low tensile strength.
    [Show full text]
  • Introduction to Structural Geology
    Introduction to Structural Geology Patrice F. Rey CHAPTER 1 Introduction The Place of Structural Geology in Sciences Science is the search for knowledge about the Universe, its origin, its evolution, and how it works. Geology, one of the core science disciplines with physics, chemistry, and biology, is the search for knowledge about the Earth, how it formed, evolved, and how it works. Geology is often presented in the broader context of Geosciences; a grouping of disciplines specifically looking for knowledge about the interaction between Earth processes, Environment and Societies. Structural Geology, Tectonics and Geodynamics form a coherent and interdependent ensemble of sub-disciplines, the aim of which is the search for knowledge about how minerals, rocks and rock formations, and Earth systems (i.e., crust, lithosphere, asthenosphere ...) deform and via which processes. 1 Structural Geology In Geosciences. Structural Geology aims to characterise deformation structures (geometry), to character- ize flow paths followed by particles during deformation (kinematics), and to infer the direction and magnitude of the forces involved in driving deformation (dynamics). A field-based discipline, structural geology operates at scales ranging from 100 microns to 100 meters (i.e. grain to outcrop). Tectonics aims at unraveling the geological context in which deformation occurs. It involves the integration of structural geology data in maps, cross-sections and 3D block diagrams, as well as data from other Geoscience disciplines including sedimen- tology, petrology, geochronology, geochemistry and geophysics. Tectonics operates at scales ranging from 100 m to 1000 km, and focusses on processes such as continental rifting and basins formation, subduction, collisional processes and mountain building processes etc.
    [Show full text]
  • Deformation Mechanisms in Mylonites at Fletcher Peak, Washington County, ME
    Colby College Digital Commons @ Colby Honors Theses Student Research 2014 Deformation mechanisms in mylonites at Fletcher Peak, Washington County, ME Ariana S. Boyd Colby College Follow this and additional works at: https://digitalcommons.colby.edu/honorstheses Part of the Geology Commons, and the Tectonics and Structure Commons Colby College theses are protected by copyright. They may be viewed or downloaded from this site for the purposes of research and scholarship. Reproduction or distribution for commercial purposes is prohibited without written permission of the author. Recommended Citation Boyd, Ariana S., "Deformation mechanisms in mylonites at Fletcher Peak, Washington County, ME" (2014). Honors Theses. Paper 727. https://digitalcommons.colby.edu/honorstheses/727 This Honors Thesis (Open Access) is brought to you for free and open access by the Student Research at Digital Commons @ Colby. It has been accepted for inclusion in Honors Theses by an authorized administrator of Digital Commons @ Colby. DEFORMATION MECHANISMS IN MYLONITES AT FLETCHER PEAK, WASHINGTON COUNTY, ME Ariana S. Boyd ‘14 A Thesis Submitted to the Faculty of the Geology Department of Colby College in Fulfillment of the Requirements for Honors in Geology Waterville, ME May 2014 i Abstract Mylonite formation and development is dependent on a number of factors including temperature, strain rate, and fluid fugacity. All three factors affect flow stress and viscosity; thus, a variance in each will affect the development of mylonites. This study focuses on factors leading to the formation of mylonite surrounded by ultramylonite of the same protolith, along- strike to one another at the center of a fault zone. The rocks in question are from the Deblois granite cut by the Kellyland fault zone, a ductile strike-slip fault zone within the larger Norumbega fault system in eastern Maine.
    [Show full text]
  • Chapter 10. Metamorphism & Metamorphic Rocks
    Physical Geology, First University of Saskatchewan Edition is used under a CC BY-NC-SA 4.0 International License Read this book online at http://openpress.usask.ca/physicalgeology/ Chapter 10. Metamorphism & Metamorphic Rocks Adapted by Karla Panchuk from Physical Geology by Steven Earle Figure 10.1 Grey and white striped metamorphic rocks (called gneiss) at Pemaquid Point were transformed by extreme heat and pressure during plate tectonic collisions. Source: Karla Panchuk (2018) CC BY 4.0. Photos by Joyce McBeth (2009) CC BY 4.0. Map by Flappiefh (2013), derivative of Reisio (2005), Public Domain. Learning Objectives After reading this chapter and answering the review questions at the end, you should be able to: • Summarize the factors that influence the nature of metamorphic rocks. • Explain how foliation forms in metamorphic rocks. • Classify metamorphic rocks based on their texture and mineral content, and explain the origins of both. • Describe the various settings in which metamorphic rocks are formed and explain the links between plate tectonics and metamorphism • Describe the different types of metamorphism, including burial metamorphism, regional metamorphism, seafloor metamorphism, subduction zone metamorphism, contact metamorphism, shock metamorphism, and dynamic metamorphism. • Explain how metamorphic facies and index minerals are used to characterize metamorphism in a region. • Explain why fluids are important for metamorphism and describe what happens during metasomatism. Chapter 10. Metamorphism & Metamorphic Rocks 1 Metamorphism Occurs Between Diagenesis And Melting Metamorphism is the change that takes place within a body of rock as a result of it being subjected to high pressure and/or high temperature. The parent rock or protolith is the rock that exists before metamorphism starts.
    [Show full text]
  • Metamorphic Rocks and the Rock Cycle
    Metamorphic Rocks and the Rock Cycle Designed to meet South Carolina Department of Education 2005 Science Academic Standards Table of Contents What are Rocks? (slide 3) (Standard: 3-3.1 (covers slides 3-26)) Major Rock Types (slide 4) The Rock Cycle (slide 5) Metamorphic Rocks (slide 6) Metamorphism (slide 7) Metamorphic Conditions (slide 8) Causes of Metamorphism (slide 9-11) Heat (slide 9) Pressure (slide 10) Chemically Active Fluids (slide 11) The Role of Parent Rocks in Metamorphism (slide 12) Classifying Metamorphic Rocks by Different Textures (slide 13) Foliated Rock Textures: (slide 14-17) Slaty Cleavage (15), Schistocity (16), and Gneissic (17) Foliated Metamorphic Rocks: (slide 18-22) Slate (19), Phyllite (20), Schist (21), and Gneiss (22) Nonfoliated Rock Textures (slide 23) Marble (slide 24) Quartzite (slide 25) Metamorphic Rocks in the Landscape (slide 26) Metamorphic Rocks in South Carolina (slide 27) South Carolina Science Academic Standards (slide 28) Resources and References (slide 29) 2 What are Rocks? Most rocks are an aggregate of one or more minerals, and a few rocks are composed of non-mineral matter. There are three major rock types: 1. Igneous 2. Metamorphic 3. Sedimentary 3 Table of Contents Major Rock Types Igneous rocks are formed by the cooling of molten magma or lava near, at, or below the Earth‟s surface. Sedimentary rocks are formed by the lithification of inorganic and organic sediments deposited at or near the Earth‟s surface. Metamorphic rocks are formed when preexisting rocks are transformed into new rocks by heat and pressure below the Earth‟s surface. 4 Table of Contents The Rock Cycle 5 Table of Contents Metamorphic Rocks Metamorphic rocks are formed when existing parent rocks are transformed (metamorphosed) by heat and pressure deep below the surface of the earth or along the boundary of tectonic plates.
    [Show full text]