Nat Sci - Minerals


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Nat Sci - Minerals

  1. 1. . :: .r..., ,,-r n r ! ! :, *! i.l tI > ir fd{lut i : : !ti-I1 r /! l" i l-IIIi ffqNERALS Minerals: l" 1. naturallY occurrtng 2. homogenuous,solid : 3. cornPositicn not fixed) a. chenric:l (clefinite but.generally b. PtrYsica 4, orderecl aiorni.c ?fl?rrlerl€fltprrrcersses s. .trtrrrt f :rmel oy ill(lrganic sr"tbstances Mi neral oi rls - natttri:liy occurri n g 4]1ryThgf witrtout crYstalline structure *Tire orderly p.arterns ihat aton:s of elements assume in a rrineral is called iis crystallin u- stru cture br-rt different * Polymorplrs r ntinerals lra"ing the same composition/elernents crystalli;,e struc:t r]es I examPles: ir.-arcasite -; -* - Pvttqano -- -l . I Calcite atrd -.-,ragonite .---__ -^^^nrla I *Alias es: 1. Caiclte - islanl sPa; 2. FYrite - 1os11i clrld 3. Quart;. - ice cnilstals Georgius tgr:cola (Georg Barrer) D",f.q Metallica- , ..,,,, ,,, , ,i, ,, . , Optical Fic;:e*ies; 2- dotrble refrtl;tion :--- rr a sroup oi crvstai rrerar oytlrald unngu*rg"3,; consists fff:1":,oJ11J:1,. to the"j"ll::::,^oj t,,,,"r, Tii;i:*n.f,-nuuu the same relation physical properttes an* s:rintlettv ancl cltsPti ,-th* same chemical
  2. 2. because ;:[l are ui ;.erlain bY Iike atoms in the same geom€ afang€Tlent ex. pr,smatic cubic *Nicolas steno - pointed out that the angles between correspo.nding faces on of a nrine:tai [quartz] are always the same "rfttuft de ILsle * Rome of *Law of consta*cy of Interfacial Angles - angles between equivalent faces crystals of the .ru"l* substance, measured at the same temperature are constant. 2. crystal habit - e.iternal shaPe ex. botrYoidar, iihrous, grar"uiar 3: color - i: ti:e brightr.ess or Carl"ness of a mineral :r-,- -^-.-{-r.. spe -trum _. - resurl of ilie ieflection of light within the visible a. idroch,om:tic - ex. rruscovite (white or c.olorless), azurite (azure blue), rnalachite (green): sulfur (yellow) b. allochr:matic - ex quartz I 4. streak is the color qiven by a pulverized mineral eXa.hernatite:streak=reddish.brown/indianred | : color = red to black b lirronite : streak = Yqllow : color = bl-,wn right that is reflected frcm I re surface of a 5. luster - qual::, 3nd intensity of lnir,eral - can be lrouPed into: r a metailic - luster "rf untarnished rnetal; the usual characteristic of dark and opaque rninerals ex. nylite, golcl h. non-metallic - ir,utatl"rizes the colored nrir erals , , l :, , b. i resitrous - appearance of resin . b.; vitrer-rus - glass u.s ouiil"urti: b.4 adamantiire - diamond b.5 silkY - silklike b.i pearly - iridescent pearl-like lusJer.., grenJv u.z -rpp"ars to be covered wiil. thin layer of oil!iIIIIIx&
  3. 3. A*6. lrarciness - abiliiy of a rninerill to-withstand abrasion or scratching - in .licated in ternrs of the Mohs Scale of Hardnesscalcite qfluorite 14 -r5 diamond 1 hardestPractical scale:CLr-coin r;, specific gravity. - refers to the ratio of the weight of a volumeof material to the weight of an eclual volume of waier - spr:ing scale; hefting the mineral by hand ex.: | 2.65 feld 2.56-2.76 old 19.3 q. cleavage -,i:iers to the characteristic tendency.of mat,minerals tc spiii. c: sepa:ate easily along certain planes - govenred by interrial arrangement _ weak,:lssl a. .ype of brr cring c. boti a and b b. greater alomic sPacing rfect very good at 9C degrees to each other feldspar fair at 90 dectrees I9,n9-.--.--i at 56.dsgleeg !r 124 degree.- amohibole e Perleei-oei-ell A Oegrees; rhomboh perfect _ diamond nerft:ct sphalarite r v F
  4. 4. formed by the rreaking in the:g. fracture - refers to the nature.of ir"ofsurr"ce cleavage oir""i"n other than those the -i- quartz) a cort:hcidal (ex b ri;i;;;iitint"Y c irreguar hai;liY d - ^r ^r"^{rrral rnta: ruintiing or- l0.parting-breakingalongp|anesofstructuralweakness;resultoftt pressure nr ll.tenacity-resistarcethatamiiteralofferstobreakingcrushingbendirig tei ring eas.ilY a. brittle - breaks or powders , n tnuiiuuble - hammered into thin sheets with a knife c. sectile - can be cutinto thin shavings cl Cttctile - drawn into wire shape ;;ilL - n*nos but does not return to origina ". elastic f. 12. fluorescence artdt. phosphorescenee 4I magnetism 14. reaction to HCI , 5. taste 16. srnell 1l . striations
  5. 5. . CI.ASSIFICATION OF MINERALIE .I-CCORDING TO CHEMICAL GROUPS native elements old, sulfur, diamond oxides maqnetite, hematite sulfides rite, qalena sulfates carbonates calcite. dolomite hclsphates apatite silicates uartz, feld l- EIGHT MOST ABUNDANT ELEMENTS IN THE EARTHS CRUST 3.63 27.72 2.83 B.13 2.59 5X0 silica Tetrahedron . basic burlding block of the earths crust *polyrnerization Silicates - most abunCant mineral group r Feldspars - rnost abundant mineral (bl Silicon.Oxygen Tctraledron cxpandcd(rl Teuahcdron (d) Top view
  6. 6. Silicate Structuresorthosilcate or (sio4)nesosilicate independent SiOq grousorosilicate (Si2Oz) epidote, hemimorphite lir.king of 2 SiO4cyclosilicate (si6o16): beryl , rinq silicatesirrosilicate chain silicates sinqle chain (Si roxene double chain SjaOrr amphibolephyllosilicate (si2o5)- sheet silicatelectosilicate quartz, feldspar framework t COMMO}{ ROCK-FORMING MI NERALS1. quarlz 6. mica I I2. feldspars3. nephelilg amphibole4. sodalite 9. olivine5. leucite
  7. 7. 4.1 lGNDOus R(Juri"u ,lDefinitions: t ut mrnerals ^r niaterials whiclr maybe conposeo . -*.. cfrnred, r:onsolidated lirlocirs - r1:ltursuv ::il;;i.;;r, glass or a cornbination of these rocxoiganic ttiatter, of and solidification "ig7lf$" fire) - fgrrned by direct crystaUiztrtion Iglteorts roclcs:fLatin nlilgttt Magntu - "l{llr,acled nrixttrrd E l,s gi il ile;tuilssleri$ii - rnol:ih t*.,?f, sases -1,:, ,lTilo",,u*d r:l:?:51 tlissslvecl ii the upPer rnantle cnist: or in rhe upper rnar due to Jtltrtr partial *atiie tqtiwer forr:retl n o "*uti ;;i;;,;ic - iieat,anrl/ot decreasT:.[:Tlfapped the earths cnrst lruithrn on tho earths surla( -;.;,i;;l.placecl -;;,;;n.,,. cltnmbers K, *,*;r{:L::::f;j::,t,# l,"f,fNa - S(Oi - PnllclPat -r ^: uirlo*tv and explosive characteristics - <rjssalvecr gases ;;;ii;:;riiu,*",r 6i]0- 1200C - rilnfie t"nt1t"*tit"J ,f SOz - ,]"rir, LI20-,:aPor, COr, - Xlrvn,j:,Pgg " 50% Si0z n. tltsnltic Inagmfl . t:900-12C0"C highlY fluid eolr6Y, sloa l"t. Grnnitic nraEitna T: lower than B00oC - highlY viscous l.Ld.tiri,--nn{erysldliaglstr . of change" -o;j-"tiy series -c^L^n i:.i.aciion $eries = J- ,1".,-tts Reactiorr Series .,i. , ., is graduallY " r in whish theearlier fornred inrler$s rnrgmafbr ;;i i i; :il:r:; il; #oi;" rm trre "t :; n ll; tthe mineral -*:iiil1: :, : Tf , tt,rti.*. in
  8. 8. ex.: plagioclase (Ca-rich torl(rich) f.)iscontinuous Reaction Series : reactiorr in which an early crystallized mineral reacts to form with the remaining licluid which constantly. changes its conrposition during cooling ancther mineral ex.. ii,,,, Enstatite + + Forsterite Melt 2 Mg SiOr MgzSiOa SiOz Magmatic ;lifferentiation : a general piocess in which the original magma with its full .ung. of cornponent elements is separated into rocks of different mineral composition a. fractionation b, filter o:essing. c. assimilation of the wall rock d. magnra-mixing Morlqresl-af.tnsglqa a. external.forces - sqrteezing of rnagma chamber and causs filter pressing b. internal forees - gur **punsion; stoping (magma move along fractures until they engulf the ho$ rock) tgnerrus rocks , - 80% of the mass of the earths crust - Genetically classified into rr| a. plutonio: intrusivb li, volcanie = extrusive I c. liypabyssal - Mineralo$ically: a, felsic - large proportions of K-feldspar and Na-plagiocl456 + quartz b. mafic - Ca-plagioclase, large hmounts of{endrnagnesian mlrerals but little quartz or K-feldspar c. ultramafic - composed entirely offerromagnesiatt rninerals with minor amounts of feldsPars - Major textures Textirre Dcscription Interpretation Phaneritic grains visible to the relatively slow cooling naked eve Aphanitic grains not visible to relatively fast cooling the naked eye _ _ Forphyritic some grans coarse, two cooling rates others line (phenocryst, sioundmass/matrix)
  9. 9. no minerals fonled r id s"tft; co4llg witElgSie eg 9XMost Abundant lgneous Rocks #- Intrusive Extrusive feiric r" ck[ K.ftiltdMptfiioclase, qtr arte, less Granite Rhyolite amountp of biotite or ampbibqle-. -. . Diorite Andesite ffie(30-50% anorthite), a,rnphibole,, (quartz may be present in gqoi*. "tGali,bro- Basalt amounts of olivine s.trapes brrfiirtiilve rock bcdies of its size or shape" Flutoir =any llass of intntsive rrrck regardless a. batholiths b. :tcsks c, dikes d. sills I e. lacolith f. tupolith (mining): gold district imflb rlancb: r.retaliic and non-metallic minerals L. : -" :- i ( 5.1 Yolungoes !- ro!r:n:io : a vdni which connects a reservciir of maguu in the deptlis of tlie earlhs crust with the surface of the earth : ejc"ts lava, fragmentaVpyrociastic rocks and gases : cons (volcanic edifice) A. Lava nffiu that h1S reached the surface of the earth different compositions ancl temperatures iesulted into lavas with a rango of physical - properry (i.e., riscosity) and fcafules. a.. paloeho* riua -:t:glly fluid, T = 1000"c; thin; smooth, biilciwy, ropy suilace b. aa l.vr - fi-il; iini.guq $low moving; seu*rh neters thick;rough : "ibtlu$; jugg*d, sPinose c. pittorv-,ta.iu1"-Iffii;pted under water or ice; (toothpaste-like)
  10. 10. I .fa ,l ll. F!rqginstic materials blown-out from a volcanic vent under pressure or -:il:,:m#*ffffiT$rrue**,smagma the raoidlv expanding gases present in plsstic state - rr*tpoi.d eitfiei+n in solid or of the fragments - classification in telTns of sizes and shapes - older lavas r a, blocks - > 64 mm; pieces of crustal layers or the congealing of blebs tllj:d ..j:a b. bombs - > i4mm; spindle/spherical masses from Iava b"l bowdung "i bz breadcrust b3 armored ,0 c. lapilli -2-64 mrn; saccretionary lapilli 4 ash-<2mm glass) +*r- Pu,nice, scori&, obsidian (volcanic T: .;, of pyroclastic rocks and lava ..:,ts, domppsite/strntevolcnnoes: altemntingla-yers Mont PelptKrakatau ex.. Mt. ttu.ii, V.r,,nius, Stromboli Etnq Mayon : a higtrly hh?{ gas charged with incandescent i nuee srdente (glowine cloud) ,rt porti"ie, ,oitrut i, i"g"*ii*r u *ouile ernulsio--n ydtidense enough to maintain lntact with surface r.ldera - co.llapsed volcano (ex Taaf,Laguna Bay) .;r .:ir comPo$ed of solidified lava flows; b. Shield ".olcailoes - broad, gently sloping.v-;rcantjes rarelY stePPer than,f:dtigrees ex. Mauna Loa : , a il. Cindur cones - volcano that is constructed of loose fragmentilpyroclastics;slopes about 30-33 degrees ex. Parictrtin BELT - PACTFIC RING.OF FIRE/CIRCIJM-PACTTTC Type of Volcanic Eruptions: -rr --^,.-|.^.rri.onh,erl gases .,cq.eq *. influencealfnir"ority of the magma aitd a{nourlf oi dissolved - .iolencs" ,*pii* i, ,rtuit io ,rr" o*gree of fragmentation and the distance "r.n quiet liberation of gases a. Fflaw*iian - ubundant outpouring of lava flows; lava fountains;
  11. 11. and scoria b. Stnoxnholinn - milil, explosive eruption of pasty, incandescent bombsql, accompanied by a white vapor cloud; discrete explosions c. vutrcaninn - btsw-out of solidified cnrsts (over the crater); acbompanied by a great- - lavaflows may ;;;iifl.wei shaped eruption cloud containing an abundanco of ash; issue d. Flininn - eruption of extrerne violence; gas-blast eruption; eruption cloud resembles an spreading out); huge Italian stone pinetree (shooting upward of the column then sustained eruPtion column Felean - extreme explosiveness; nuee ardente Phneatic g F.trreatomagmntic l h. Uliru-Ptiniatr - excessive emission of ash resulting to negative landforms lLE n*Vqlpgnlg-Hazards ( c. lava flows e. caldera collapse a. ieplua fall d. lahars f. tsunami b. pyroclastic fhll lrnportnnt: geothermal energY (ex. Makban, Bacman, Tiwi) s[rMM3nY lava fottntains
  12. 12. :,t,il,i .. j,::, r. i.:r: .il..l_,1 ffi ffi i+:ir :ri,i .i;i b9& oir 5 L)-rr #6p ! I !Ii:r;;i i ?.ii:li,iiii-ig btj;iEln Z .Ei.i.i1.1 Y Iiili$[ 6 0, (s E E z I {}::r li:i; l:i+.i ::: olii :i .E r, i tr...:+i o = d 0) o) o .c. 6@ 7 -rao q LY:t !i:t
  13. 13. ,i iii wil,ATr{rcntruc nivn ER,osnoNiVE,:XI.!!Eit,lNi- is the physical disintegtation arfci r,hernical decontposition by ivhichrocks iire changed upon exposure to "agents" at or near the earths surface, with little orno lranspo;t of loosened or altercd Inateriai *- agents - hydrosllhere, a-tmosphere, biospher-e.4. l4cch*nical Weathering - is the breakdown. of rccks into smaller fiagnents byvatious ph1151"1 stresses - ::tictly a lthysicul ploces:; willxnt a change in chemicalc1tilP)riliott fr4 erhilnicaN Weath ering Frocesscs a. ice wedging/ttost wedging b. salt crystal gror,vth L:. slrceting/unloading - releasc of confining p:ressure exfoliation - fonnation of cprved sheets of rock by release of pressure d. anirnals and plants e. tlrermal expansion and contraction - seasonal/daiiy temperature changestr]. Chenrical Wcattering- is the process"by rvhich chenrical reactions transform rocksand nrinerals into ne;, shemicat cornbinations that are stable under conditions prevaillng ator near the earth"s sur{-ace lioie: more ef-fectittc itt xarmer clintcle:i - lrcat increase,s tlw xtte of ma:;t reucf irnts Chcnricnl Wcatherinq Proccsses a. Flydrolysis - H or Otf of the water anAffinUe ions of the rninerals Ex. I(-ibldspar 2l(Alsi?o8 + 2tt2co3 -F 9FI20 Ortlroclase Carbonic Acid Water Al2iii205(ot-t),r -l- 4l-I4sio4 J- ?tc + 2{-ICo3 Kaolinite Silicic Acid Potassium Ion Bicarbondte l.on {, :--*ffi
  14. 14. . ,1; l). ulSSOllltl0n - Fr2U -- --Llnlversat solvent Ex. b.l NaCl T HzO Na -F CI 1- FLO b.2 FITO COz -,----+ HzCOr CaCOr T FizCOr ------+ Caun F 2HCO:- c. Oxidation * is the cornbiration of oxygen ioris ivith cations Ex. 2FeSz + 7O:r + zHzO F 2Fe- + 4SOt + 4F-t+ 4Fe* -t- oz {- 4# -_|4FErrr + 2H?Ogl&qlar dalrygolbstlqg or "onion-skin weathering" -- produces spheroidal boulders ofrelat ively untveathertd materialX{.esults/f roducts: a. regolirlr - fragincntal and uncor.rsoiidated rocl< material that has coarse grains rvith angular edges and a composition sinrilar to the unweathered rock " b. very large increase in the surface area of the v/eathered rnatedal , f,,. soluble rnaterialsXlilr:tons afTccting the nntes o{ weathering:I. susceplibility otthe consl-ituertt roirrurals to rveatltering - Goldich Stability Series -- nrinerals forrned at liigher temperatures and pressures tend to be less stable in uveathering environment than those formed at lower temperatures2. climale or intensity of the weathering processes -- total amount of precipitation - intensity olrain -- sr:asonal variations -- infiltration -r -- run-ofland rate of evaporation -- teulperaturerwnnn, hunrirlclimate Vs. coid clirnaLe -J. amount olsrrrface exposecl to the atmosphefe f,i?0$/Ory - forcehrl physical removal of material frorn ihe parent rock, acconrparried by transportat.ion and eventually end in deposition a. running vrater d. ivind f- mass wasting: : b. grouncl water €.waves ald currents g. oigarric activi c. glaciers
  15. 15. " n Dcpositio n itrtti [ix.hiticatiorl : I I l-- Lithifliq:ation - is the term for p group of processes tlrat conrreft loose sediments into sedirlen.rarr/ rocks u. C1:me6talion - the process by which sediments are convefted ilt<i roclr by the cliemical precipiiation of rnineral material / cqment among the grains of the sediment I + silic.r, carbonates and irolt oxides t{ is tlie loss in over-allvolunie and pore space as sedinrent t-, . Ccrnpactittn = particles are packed closer together by the weiglt of, overlying rnaterial Cry:;tallization - refers to crystal developmelit and growth by precipitation fiom solution; no cement; grains are held together by inierloclcing crystals Ser{inrept:ltion - tlre process of fornring sedinqnt in layers, including ttre separation oi rocli partioles fitlnr the palerrt Inaterial, transportation of these pa.rticles to the site o.l deposirir:n, actual cleposition/setiiing, litlrification and consolidaticn into rock,
  16. 16. . SEDIMEhITARY ROCKSSedimentarY Rocks:- Latin woi-d, sedimentum = "settling"- formed from consolidation of materials from pre-existing rocks, fromprecipitation and from secretion of organismsSediments - finely divided matter consisting of mineral grains and organic processes,.transported bymatter derived from pre-existing rocks and from lifeand deposited from alr, water or ice - origin: (1) weathering and erosion of pre-existing rocks izi cnemical prebipitation from solution (3) secretion of organisms Ocean = ultimate destination Partlcie size classification for sediments [dden-Wentworth Common Size Glass . Sedimenf Narne Particle Name Gravel or Rubble 1116-2 1/256-1/16 Two Maior Textures of Sedimentary Rocks . and particles 1. clastic [Greek k/asfos, "broken"] = discrete fragments crystal pattern 2. non-clastic texture = minerals forming an interlocking .
  17. 17. Iypes of Sedlrrientary Kocr(sa. Detrital sedimentary rocks.particle size is the primary basis UOOenlWentworth Common Detrital Rock Size Class Sediment (Particle Namq)- Name Boulder Gravel Conglomerate UI Cobble Rubble Breccia Pebble Granule Sand Sand Sandstone sitt Mud siltstone Shale or mUdstone Clay clavstone precipitation of minerals b. chemical sedimentary rocks: formed by direct from solution. *Precipitation occurs in two.ways: (1)lnorganicprocessessuchasevaporationandchemica| actirTity can produce chemical sediments - iximprei: dripstone and halite (salt) (2) Organic processes of water-dwelling organisms form biochemical sediments Texture Composltton Rock Name Group Clastic or non- calclte, u?uu3 Limestone clastic Non-clastic Dolomite, Dolomite (Dolostone) lnorganic CaMq(COs)z Non-clastic MicrocrYstalline Chert quartz, SiOz Halite, Rock salt Non-clastic NaCl Gypoum, RocK gYPsum Non-clastic CaSOo2HzO Clastic or non- Calciie, CaCOg Limestone Organic clastic Non-clastic MicrocrYstalline Chert ouartz, SiOz Torc6sttc Altered Plant Coal remains
  18. 18. -..SedimentarY $tnuctu res environment*provide additional information with regard to the depositional :rmed as bedding or stratificationl1, l-aYering [also t( :l layer is 1 cm or more 1.1 strataor bed: thickness of tftu l.2taminafion:thicknessofthelayerislessthanlcm (e.g., change in *may result from differences,Qetween |ayers in texture color or cementation grain sizeiti*iui tomposition -beddingptanes.=flatsurfaces.alongwhichrockstendtoseparate and the beginning of e end of one episode of sedimentation another (b)pauseindepositioncanleadtothecreationofbeddingplanes 2Ripp|emarks.=smatlridgesofsandformedbymovingwindorwater 2,lCurrentripp|emardE:lfairorwaterismovingessentiallyinone direction 2.2oscillatoryripplemarks:Resu|tfromtheback-and-forth movementofsurface*.u"inshal|owwaterenvironments 3Cross.beddingisanarrangementofsmallbedsatanangletothemain sedimentarY laYering by a Progressive 4. Graded bedding is a tYPe of bedding characterized through the bed decrease in grain size upwaid 5Mudcracksarepolygonul",.u.k,thatformwhenmudshrinksasiidries
  19. 19. fiNETAMOffiFffiC RCCKS Metarnorphic rocks = rocks resutting from changes in temperature and pressLtre ancl frotr changes in the chemistry of tlreir poie fluids. = can be formed from igneous, sedimentary, or previor-rsly nretanrorphosed rockb. = solid-state .reaction = consist of a fabric of irrterlocl<ing crystal grains, usually with preferred grain orientation. *Changes new minerals, textures and structures -,,.t.* -) occur in the solid rock; witltout melting of rock I. Principal agents of metamonphisrn a. lentperature - rarely below 200oC, upper limit is ihe meltingtemperature of tlte tock b. Pressurcil b.1 confiping/static = pressLr-e applied equrally on all surface of tlre BT5r"r, ecl/dynamic - pressLrre applied unequally on the surface of a body b.2.1 compressive - flattens objects perpendicular to applied pfessLl[e b.2.2 shearing flattens objects parallel to tlre applied pressLlre *Fcrliation parallel arrangement of textural or structrrral features - in apy type of rock; planar structure that results from flattening of tlre constituent grains of a metamorphic rock c. Chentically active/migrating f/uids - loss and gain of ions and atoms - snrall arnir-rnt of pore fluid provides an inrportant medir-rrn of transPotl Mletasornatisln
  20. 20. introduction of ions fronr an external source generally connected with magmatic intrusions Ir T-- new material (front magma) + pore fluid = new mineral ilil l,/ stable in the new chemical environmentl[. Types of metamorphlstm a. Contact/thenmal metarnorphisrn = metamorphism resulting from the intrusion of lrot magma into cooler rocks. *dorninant factor: temperatu re fvlelarrorphitr Qracle. Ll. Regional metamorphism = metamorphism caused by relatively high ternperature and both directed and confining pressure = *affects broad regions of the Earths crrrst, usually in areas of tectonic activity. = foliation *heat: great depths, earth movements, batholiths "pressure: burial, tectonism . , | .t t,. -,:. c. l-lyclrothenmal nnetamorphlsm = metamorphism cauSed by migratingftLridsandbyionsdissolvedinthehotfluids. lll. Textures of dretamorphic rocks .,,. . ., a. slaty = nearly perfect, planar, parallel fotiation of very fine glainedl platy (flat) minerals (i.e , rnicas); low-grade tnetamorphism ,, l,l.t .li,..1,.,.....:,,. ,
  21. 21. b. Regional meta*orphi"* = metimorphiir .uru-d bg relatiu.lg high ternperatrr. both directed unJ .ot fining Pressure "nd = u{Qd..ts brood regions of th. Earths crLrst, urrullg itr areas of tectonie activity = foliution *m e nfs1 balh hlh s . ::::;:::1i : f i:i::: J c.. Hgdroth**uf meLamorphism = metarhotphitm .uut.d by nigrating fl,ri,Js bg ions dissoln.d in the hot fluids" .und111. fct:turo of mctamorphic rocks a. slatg = nearlg pe#ect, planat-, purull.lfoliution of fine-grained pluy (flat) minerals (i.e., micas); low-grade metamotphi"t phglliti. = s parallel (but wavg or wrinLled) foliatio n o[ [in"-g,ained (ol.uu;onulig ,n.diur -g,uii.d) platg minerals (i..., misas and chlorires), .ih,biting a silkg or me13llic lu*er; relativelg lo*-grad" metamorphittt (.. ,.l",,rtose = purull"l to foliation of m.dium- to coarse- "ub-purallel qrained plutg ninerals (micas and nhlorite); hgh- e."d* rnetamorphitt gnei-ssrc = p^r"ll"l to uub-purull-l folirtio. of t.dium to coarse- ,:-.,ri,r"d platrl minerals in alternating l.g"ru_ of difFerent cc,mposition; jirter*-ditt"- tohigh-grade metatotphiut g rnoblustic = -rniform g;ain size o{ equant or- l.andomlg oriented s:rains
  22. 22. t l ( | l. | |- r,l l I t horntelsrc = tine-gained rocks with grains tendlngto be lntergrown --1--L- irr rarrdorn orientation M. C.lassi$ication A. tlnioliatud with qranular texture:l b. rcliiated Namc Texture Parcnt Rock ate Slaty Tufl-, shale P Slatg (silkg sheen); Tuff, shale phylliti. ,5chistose basalt, gabbro, tuf{-, andesite, shal., rhgolit. Gnciss Gneissose - Granite, rhale, diorite, ihgolite oCataclastic roclcs= r.o.ks that htu. b."n granulated by .tuthing- + Mqlonite= uataclastic roclcs with floy textures-
  23. 23. *l DIASTRC}PHISTJI / ROCK DEFORMATION r.olumeDeformation = a general term that refers to all, changes inancllor shaPe of a rock bociY = tfr" strain yielding of a solid to applieci stress ,*Stress = the amount of force acting on. a rock unit to change itsshape and/or volttme a. confining Pressure - equal b. differential or diiecied . b.1 compressional - shorten a rock body b.2 tensional - elongate or purll apart the rock bodY b.3 shear - sliPPage *strain = is tlire.change in shape andior volume of a rock unit caused bY stress Iypes of deformation (strain): a elastic deformation = object returns to iis original size and shaPe when stress is removed b. plastic.deformation =.a permanent change in the original Lr,up* o.f a solid that occurs without fracture c. ruPture , , . i Rocks that defcrm plastically by foldin$ and flowing are said to be ;;;;i;". Ontf.* otr*r nanditoikt tested undqr surface conditlohs ],r""..t"i* -[Ji."irv, uri olce they exceed their elastic limit, *"rt:b*hau* like abrittle sblid and fractr:re- This type oi l"t"i*"ti;; i. "orr*o brittie failure
  24. 24. Fqs+src *f{e,o*rv,g -{Sabdhaviot of roo{rsla. inherent ProPerties mineralogy, gtain size, porosity etc --nlinelalswithstronginternalmclecularbonds;=brittle -- weaker bonds = ductile -- qLrartzite, granite, gneiss = brittle ductile -- rock satt, [ypsum-Marble and shale = L:. time -- quicKtY = fracture confining Rressure) high = plastic d temperature / ,i, e. solution - loulers rock strength MAPPING GEOLCIGlc sTRUqliuRES Outcrops - sites where bedrock are exposed geological feature Attitude - refers to the 3D orientation of some ex. bed, fracture intersection of an strike - direction of the line formed by thefeature planar imaginary horizontal plane and any o - trend , Dip.istheangleofinclinationofthesurfaceoftheplanar plane feature **ur,-,r6d from the horizontal
  25. 25. 4tt - sinrply a bend or waverike undulations in bedding, foliation,ciea,;ace rir other planar featlrresParts of a fold: , a. litnbs ar ilanks - twcr sides of a fold b. hinge - line of maximum curvature in a folded bed c. axrs - line paratlel to the hinge; line moving parallel to itself that generates the fold tt..,, d. axial plane - imaginary surface that divides a folci as symmetrically as possible e. plunge- angle between the fold axis and the hor-izontalTypes of folds: i.l. anticline = "arch"; convex upward b. syncline. = arches downwarcl d. synrmetrical = limbs clivergle atthe same angle e. a$ymrnetrical - overturned = one limb is iilted beyond the ver-tical recumbent = axial plane is horizontal f. plunginE = iolcl with Cipping axis g. monoclines = broaci flexures; one limb h. domes and basiri
  26. 26. FRACTU RESA" Joints = are fractures arong which no appreciabre displacement has occurred = may harre almost any orientaticn _ verticar, h o ri zo n ta,:::t ;"#:,Xifl 1.,=Causes:a. columnar joints form when igneous rocks cool and develop shrinkage fractures ex. Devils Causeway in lreland Devils Tower in WyomingL-r. sheetingc. rocks in outermost crust are cieforrnecin" ,Joints may be significant from an economic standpoint*" ,Joints also present a risk to the construction projectsB. Fadlts = are fractures in the Earths crust along which slippage or displacement has occurred.Fault terminology: 1. hanging wall = the rock above an inclined fault 2. footwall = the rock beneath an inclined fauli
  27. 27. Types of faults: a. Dip slip fauits a.inormar/gravity faurts = extension; the hanging -"7"r wail rrq moved down relative to ihe footwall uqr has 6 graben (German word, "grave,;1 = wedge_shaped rock dropped downward block of ll,H:;::"tnt of rock that have moved upward relative to a.z reverse faurt = compr"rrion; hanging wail has, relaiive to the moved up footwall; high_anglediI a.3 thrust fault = gompression; wall has moved up, relative to ihe footwail,; row-angred _hanging 1so" oi +6"i-, b- strike-slip faurts = raterar faurts; high-angre faurts in which the displacement is ho.rizontal, parallel to the stit<e of the fault plane, with little or no vertical movement. b.1 right lateral stike-slip faulUdextral b.2 left lateral strike-slip faulUsinisiral c. Oblique slip faults
  28. 28. EARTHQUAKES AND REL cf the earthEarthquake sudden motion or trernbling release of energy - vibration in the earfh "ur.u-d by ihe rapicl *Most often are caused by slippage along faulisElastic Rebound TheorY: oFl.f:. Reid, Johns Hopskins University slour deformation of the crust (creep) until strength of rock is - over exceeded. Then, ruptttre cccurs Start - 1906 San Francisco Earthquake adhquake, a. in the 50 y"u" before the 1906 san francisco e surveys takln in the area recorcled an offset by creep over 3 6 m, this movement , il:l"Ji,*nt during the 1906 eafthquake was to 50 years took plaiu in +O ieconds as opposed an earthquake originate Focus - the poirrt at which vibrations of Epicenter-pointonsurfac*ot"",-tr.irnmediatelyabovefocus Rupturesurface-areaonafaultplanethatexperiencesmovement cluring an earlhquake event any atqcri, tra vels through rock, produced $eismic Waves .- ^^,r elastic waves that by an earthquake or exPlosion Whenanearthquakeoccuts,seismicWavesaregivenoff.Thisis Wives are created simiiar to throwinga stone tntol quiet body of water which move out fiom the point of impact Energy is being propagated along these paths; and as it moves some of the energy is lost its energY The farther the wave travels the lower
  29. 29. Seismograph - iirstrurnent that records seisrnic Seismogram - record made by the seisnrograph Types of seismic waves:. i- Body waves - radiate outward from the focus in concentric spheres and travel through the Earths intericr a. P-waves - Primary waves, Longitudinal waves, Compression WAVCS - involves alternating compression and expansion of the material through which it passes - similar to sound waves, like ihe nrotion of a spring or slinky, a push-pull rnotion - movement of rock particles is parallel to the direction of wave propagation - fastest waves, travel 5 to 15 km/s - may pass through any kind of solids, liquids, or b. S-waves - Secondary waves, Shear waves, Transverse waves - inVolves oscillation of rock particles perpendicular to the direction of propagation - like sending a "wave through a rope - slower than p-waves, 4-7 km/s - may pass through solids onlY 2. $urface waves - Long waves, L-waves - radiate outward from the epicenter and travel along the outer part of the earth; generally slower than body waves - greater amplitude and longer period - cause the greatest destruction a. Rayleigh vJaves - rock particles move in a vertical rolling (orbital) motion, somethinglike ocean waves b. Love waves - rock particles move side to side in a horizontal plane - very destructive and travel faster than Rayleigh waves Pvelocit.v } Syeto city > Lvelocity
  30. 30. Locatine an earthqrrake - in orCer to locate an earthquake, at least three seismograph stations are needed - if only one station: distance to epicenter, along a radius from station - if two stations: two possible epicenter . - three stations: unique pointMeasurement of Earthquake Strenqtha. lntensity - an indication of the destructive effects of an eartlrquake ata particular place - affected by: distance to tire epicenter, total amount of energy released and nature of surface materials - Mercalli scale (lflodified Mercalli Intensity Index) o qualitative and subjective o measure of damage and felt intensity o determined by siteexamination and interviewsb. Magnitude - total arnount of energy released during an earthquake - based on direct measLlrements of the size (amplitude) of seismic WAVES - total ener$y reieased - calculated fiom the amplitr-rde of the waves and the distance from the epicenter - Richter scale o quantitative o open ended, <1 to infinity o logarithmic (a magnitude 2 is 10 times more powerful than a magnitude 1)Effgcts of earthquakes 1^ ground shaking and rupture 2. landslides 3. iiquefaction 4. tsunamis (seismic sea waves) o originate when water is verticaily clisplaced during: earthquakes uncjersea landslides (turbidite fiows) undersea,rolcanic eruptions (e, g Krakatoa, 1683)
  31. 31. u6F{ r rcf Eo. rr, r- ,,*rF I - lr r*a- t@ds. 4te4+_gAgrfih€4r&rmCoC,ffin tfic gm&rs sititace, charrging their positicns relaiive to one another * ocean floor remains stationary as ihe contirrents ptowe( thror_rgh it -- tlot nev/: a. Buffon - sirnilarity in fossils b. Snider-Pelligrini - similarity in coasilines *"llorth Arnerica and Europe --Alfred Wegener - Father of Continental Dr-ift continents had been united into a vast superccntinent called Pangaea (Pangea) a. Laurasia (northern) _ North America, Eurasia; b. Gondwana (southern) - lndia and the rest of the continentsiii - driving mechanism: rotational and tidal forcesi -- Wegeners lines of evidence:l a. ligsaw puzzle fit of the continentsi,i b. distribution of fossil plants and animals examotes:i b ] G/cs opteris sp. and Gangamopfe4rs sp.i b.2 Lystrosaurus.sp. - found in Antartica, Inclia anc.l, I South America; land dweller (Why not North Arnerica? Distribution of fauna is i )u,n "r:::5X,.,,:uJ;::3 : Arr e ri ca and s o u tir Arrica, i:. aquatic reptileli c. continuity of geotogic structures - lndia, Africa, South America, Australia and Antartica . . tillites j fossils i)l, - identical patterns oiscratches and grooves fornred in the,. rocks I d. nt*terhs trf pateoclfn"atgs ard qlc"tehby,, rn +he Soratho-rn l-te.rrrsphere,1 - pr*,.r*I. ; r.,[.-*o, -+"r*otrt"; rn ftr*artica ,;;;;;;-" , once near tfie aqua*or .i.iFters v:. *i:rers - (tqao) cpiii-.aa< due rnainry io -rhe onc,r.0.,:t,ur,.,
  32. 32. ltl rrf t ocearl: l o in oPen ^^^ -,,^- , a tlr?V travei uP to 700-800 km/hr " wavelength >100-200 knt r wave height <1 m o approacnlng a coastline )hing d :"i:-l:^*^^^- r wavelengih decreases (up to . h;;;iintruu*", to compensate for low velocity : 30m) < velocitY is reduced to 60 km/hr of lakes bays rivers etc) 5. seiches (oscillating waves on surface 6. fire 7. t"gionalbhanges in iand elevaiion.SeismichazardmapshqyearthquaKeriskinaparticulararea. -indicateprobabilityofanevent,andprobabi|ityofacertain amount of ground shaking- Short term Prediction }some=u""",byJapaneseandChinesebyuslng|u|esl other data F factors considered useful: 3 / o"toimation of ground surface :";il;i**i tune connecst two .water-fill:: "::tuiners D gravimeters - measures changes in -.-graviiational or falling land; of strength brought ab,out ,nV liting ;;iles in deisitY of rrnderlYing rock cf€e PrTleter u :- .. proton precession magnetometer - detects changes tn [t"* magnetic fielcj "uifts " lasers / sesismic gaPs along faults r, -.. / puiiurn= ind frequJn"y of earthquakes : :-,:1. uno*uf"tts animalbehavio ",, l.. ,:,.,,.,,ir-..;:",- / ,, . {CI ,/, changes in wateri#;iltbJity t**pe.rature in n*i 16 ", :x1"#:3?".#Tl,o*r ,."=irliyily. . ,-----,-^li..a,^ deep *ullt ,,ti, -,- .,,i.,,. tt,
  33. 33. , r .,,..)> rocks contain minute amounts of magnetic minerals that align with the earths magnetic field}.directionofalignmentandinclinationfromthehorizonta|indicatesthe position of the magneiic Pol" within the rocks the time and place the rocks formedn studies show that poles were in.different positions relative to a continent at various times in the geologic past t "-o",1it;:,", had moved (2) continents had moved - continents stationary, poles had moved: paleomaqnetibally determined pole positions for a particular time should be the same or all continents - continents had moved, poles stationary: pole positions slrould differ among the continents
  34. 34. SEA FLOOR READIF,IG -- Hess,oroposed that the sea-floor mighi, fYlr)i/rn^ I I rv v il ty :l crest of the MOR doivn the flanks to disappear finallyby plunging ,- spreadingcenter = ridge crest - subduction = sliding of the sea neath a continent- Driving force of sea floor spreading: a. Hess: SFS was clriven by ntle convection + Meinesz andHolmes hy earths internal heat r beneath the crest, b j uplift of the spreading,ridge jlstuoiunt formed simpry permits sriding vrithout the help of conveltion curid:it ll: c subductecJ slab is rnore dense b;g.urr" it is coid tends to pull the slab along as it dives .ri;i :ii -; ,iiObjections. : " a. viscosity of the magma il , b. rocks are very weak under iiliEvidence for SFS: iii , 1 thickening of the sedimentary r3x,"r away from the ridge Itl 2 the age of the sediment restiilgi on the ocean floor increases away fronr the ririge .:ii- ,l1.. 3.stripesofmagneticanomati"s,.i.:i, " normar earth fierd - a!_ditir13,and strng magnetic intensity " reverse _ subtracts from tfleipr*="ni-ragnetic intensity.leaving low vatue :ii . e :i:r .:
  35. 35. p uqrr. rrcrotrtigs rHEOnv ilii eAding (1eo8)- or the ocean r1or "".1:;lT,$JLi.,-nitffi;iol;uu; reaturesmountain ranges plus otitnttt; ;i ea4hhuakes; volcanoes, etc illli i:l1l i i l:l;l I ii{dt is part of the earths surface mobile slab of rocf t{{XtPlate = large, l continental :: entirely "t idi& oceanic crust the idl#;oceanic crust or both ifli on the same plate are not = assumed to be rigid - t*o$[drus - motion .^la*irro tb each othe;fii th Othgnl in -r:^^ relative iiiin/linot Plates: Major plates: il;,-- ,,.it. : li r. Southeast Asian- 1. American ,rli z. Nur"u 2. Eurasian :ii 3. CarriC"an 3. African :: i. inJiun-Arlstralian ii 4 Arabta Lrqr6 Philippine 5. pacific ti ,5 6. A.ntartic "l ..^ , iirr outer shetl L.iihosphere = earths rigid i! Astenosphere = Low Velocity Zonei rlue to an incre*$.pr"=icaltyduetoanincrease in Pressure and terRberature allowing the plates to iuv"t = acts as a runritliilS move .l I ii distinit unit all maior interactions plate b oundaries between patesoccur along I i* " - ^!: t,: r" a mountain building -rnd seismic activitY volcanlsm , !i: where plates a divergent nouhdaiiS:- : maierial from nff.v,: tt tllupyvellin$ of upu*,i"=iift*g t; create new sea floor:r
  36. 36. :, b. conver-gent beundai-ies = wnere . plates Inove together, causing orte of the slabs of the liihosphere to be consumed into tHe mantle as it descends an overriding plate c. transform biundaries = whete plates slide past eactr other creating or destroying lithosphere i ::. Features: .;i. ;r 11.., A. Divergent Boundaries iii: : a. oceanic divergence - mif,1ked by the crest of the MOR and basaltic voicanoes :iii: ex. Boundary behrueeriliazca and Pacific plates 1, b. continental divergence * niarked by rift valleys ex. East African rift vallqys Red Sea .t,: B. Convergent boundaries : a. oceanic-oceanic .onuBrg"n.* : ?, 9::alit plates converge, one plaie subducts under the other a.1 Wadati-Benioff zones of earthquakes a.2 volcanoes I. a.3 island arcs (Philippines, Japan, Tonga, Mariana) a.4 inner wall of the"trench consists of a subduction complex and fore-arc basin tVr:fe. Marianas type; fensioiip/ environment, sfeep-ang/ed st.rbducfiorr , b. oceanic-continental cohvergence - plate capped . by oceanic crust is subducutecl under the continental piate t: b.1 subduciion complex,fore-arc-basin, back-arc basin b.2 edges of the continent become deformed intoI young mountain ranbe " b.3 volcanic/magmatic.a.rc within the continental crust continental-continental,Qonvergence - collision of ilvo corrtinents .::I ili,l
  37. 37. :llen{:j 11.1. : l ,: l:, : . , rrii":ii rnl .iil;tu :l:i:i c.1 rnar-l<ed by sutr-rre zones (olci sites of subduction) , .,1:. r ,: : c.2 majestically high mountain ranges in the interiorof .aneWlargercontinerr:t(e.g.lndiaandAsia) r., :it i :lr,: c.3 marked by broad belt of shallow focus earthquakes ali-,,1-l g the nu me[ousi:far-r lts i: 3. -fransforil Bounrdaries iii it:: marked by shailow focus eatfhqLiakes ,rl:l: - first motion studies indicateiil$trike-slip movement ifi What Causes ptate motions? iti illl a. mantle convection - involves nCiOconielJtion cells anr:i hot mantle iirock ,, due to: iliI o a.1 magrna intrusionri on the ridge brest.prrshing tlre.r plates o ,. a-? currents mov-ing away carry the plates *"Push i-iypothesis" :1. : "difficurlt to account for the vepical.cracks in the rift zone . ,..,iri)lli i b. sitbdt-rction pulls the plates : r:.l.1,:l *"Pull Flypothesis" "nan account.for the tensional cracks but in.some ridges trenches there are no r1.... i C. plurnes and hotspots ll *plumes - narrow colLtmns of hot mantle rock that rise anci spreacl radially outwald formiiig hotspots of active volcarrism ex. plurne under Hawaii , i{i,, ,t$ ii:jr i;,,,.;,,,t .i$$ r :,j: .,:.:.: t, ,,$, . .ii: ,$, ,i it ,: ii ii i,: $ ii