Mountain y*\ r v vi Oceanic crust Continental crüs R&duction in elevation due to weathering, erosion. and transpo rt of materia I s D eposition ot sediments Oceanic crust Ocean f Uriíft ^ Uppermost mantle Slow ilowage toward Asthenosphere region of crustal thinning Sediments Oceanic crust ' ¥;■■■. Cominentalorustvfí * Q V —7— Moho i Uppermost mantle Uppermost mantle Subsidence from weight of sediments Asthenosphere Ť (c) 1 * Asthenosphere r-* (a) Oce»0 Continent ^ 60 Moho Ultramafic rock OCEANlc PHUST ■o 'Jo LITHOSPHERE""^ 07/ (b) km 10 j :o 40 50 - 100 - 120 - 140 T 160 Mountains rnntinontal OCEANIC CRUST —v-^ oUIILH luniui "~~~~—-—_____shelf sediments ---------(Water)----------- Felsic rock ^V- -" Basalt CONTINENTAL CRUST . V Moho Mafic rock / <£0-----^"^ "Crustal ^s^*^ Ultramafic rock ^*k_/ Moho Ultramafic rock (Base of lithosphere) y - / ASTHENOSPHÉRE LITHOSPHERE / / 0.100. 200 km ill 0 100 mi ii - - (Base of lithosphere) y ASTHENOSPHÉRE Ultramafi c rock - 20 - 40 60 -. 100 Geologie na konci 20. století přešla od fixistických statických interpretací k dynamickému pojetí vývoje Zemč. Dnes dominující paradigma geologie - tektonika litosferických desek - zdůrazňuje výrazné horizontální přesuny kontinentálních bloků. Za jejich hnací motor je považována tepelná konvekce v plášti Země, která je určována tepelnou výměnou mezi žhavotekutým jádrem Země a poměrně chladným povrchem. Teorie litosferických desek předpokládá, že konvekcní tepelné proudy v plastické části zemského pláště vedou v místech vzestupných tepelných proudů ke vzniku divergentních rozhraní a v místech sestupných tepelných proudů ke vzniku konvergentních rozhraní litosferických desek oceanic crust Mechanisms (b) Uthůsphere (d) Subduciion Spreading Plume boundary Inner core "t y. Types of plate boundaries divergent: mid-ocean ridges convergent: collision zones volcanic arcs strike-slip: San Andreas fault Alpine fault, N.Z. Examples of Plate Boundaries O-C convergent w Amies 0-0 divergent Ocean Mid-Atlamic crust Rrdge fcrft C-C O-O divergent divergent Mi valley Carlsberg Sea RjdgcFlrtt level O-O convergent Japan volcanic arc O-O O-C divergent convergent East Pacific Riscftift Andes I Fig. 20.8a,b »Triple Junction Bulge over rising mantel plume Development of 3 radial rifts Red Sea Gulf of Aden East African Rift »Aulacogen Convergent Plate Boundaries •oceanic-oceanic convergent plate boundary •continental-oceanic convergent plate boundary Konvergentní rozhraní představují místa vrásnění, vulkanické činnosti, vzniku pohoří a kolize kontinentů Thompson and Turk: Earth Science and the Environment, 2/e Figure 5.12 HINTERLAND (R'sing Mauiľcin Range) «v-flW* center fc Subduction Ocean -x^tí^vyľ^-----------"V1---------— **» zone trench ■-^'"^^■B Bubé^T"........-ľ^t SÜIUBE ZONE FDRRAN1BASN 4 rhlNHWhtuK PrtiyaJing cbrtie iwJgtcf Mobs« allot Atscett iratáilg íaj loig nytt£Ti -í"J Y 4 l r" A 'J -^ ■*■ T ^ * "P M * ^^^ ť-j^ ^ * ■J va^ -1 "í í v. ■q -T \y ^ -f \y ^ -f \y q -f p- -j -f I- | ■-k -""-T--* V "T "í "* "P "* ^ "P ■* ^ "P * 1 H1 V^ f4'< T-l 1 V -1 ^ ^ -í — ■. ^■i Aiuš^QwtiiiaOÍMJrtn 1 v "ú H vol v^i ľ-11^ v-*"* —p ,J j _■ -p i.- .■ —f i.- .■ -f i.- . ■ -p u .■ -p L _■ WtdptflfStdrnin** JrWtakd-udMAd] - i ^-T-fl ^ "P "* ■*"** f -i "* V -1, ■* '+ ■+ ■J -T k ^ -T ľ J -T y ^ ■T ľ^ ■ fr&ií him Ní im H-ŕH-ŕH-ŕH-ŕľ-J-ť ^ ■J k'j'J y>4^ f ■-! * Ť--l^ v-Jl v-il ^Jl f^1* V -i * V ■-! V JM -'k^-' ľg-ŕ IVyj-' k^ -r H "* ^ -t * * -t v * -t kyj _^~T0 měl lín n r^/\ E U P A S I A IM PLATE ,■:,-■ ir:i i i:;" JE million yepraa^o 55- milion '___ y*äre aga r ľ i /--i INDIAN OCEAN BEFORE Tip of Indian plate INDIAN PLATE Very i>ld lOCk, 2 to 2 1/2 billion yoars old Reference point AnCiértt ocean k ľ:rnf,l EURASIAN PLATE / "INDIA" j Land mp» ■ 71 million years a-go if u SRI LANKA AFTER ^^ -^ J o M ■ i--.:■'. av a* Rid n g TJ b ftt j n PI at c í> u Reference point INDIAN PLATE Ancient ^ůceanic ^ cruat •Sedimentary Deposits fore-arc oceanic basin trench litharenites back-arc basin fore-arc basin oceanic trench Trench ——* Oceánie crust I Island aire J£ i-J';:-1. ., ^ ■ > -■■■■■ ■<'T». ■» * *^ "■- .:._,.. Subducting 100 km 200 km -l"£----------' - mrr? Continental Oceanic líthosphere """"-crust Asthenosphere •Continent-Continent Collision Regional metamorphism -granulite, amphibolite, greenschist, •blueschist metamorphism, glaucophane •Suture zone- foreland basin, thrust faults regional metamorphism Trench & Remnant Divergent Melange Ocean Margin Belt Basin Te«¥e*aturfl{ptl) o: ■ooo * 12CÜ I r-.- »Subduction Zone Complex ►melange »ophiolite suite melange Idealized Ophiolite Suite Deep-sea sediments: shales, limestones. f cherts, turbidites, fossils of pelagic marine organisms Bajnltic pillow lava j cut by dikes Gabbro. evidence of metamůrphism Peridocites and „ other ultra mafic rocks, often showing metamorphism Deep-sea sediments Pillow basalt Gabbro Peridotite Fig. 20.14 Accretionary Tectonics »Allochthonous Terrains »allochthonous »autochtonous •red - blocks from continents other than N. America dark green - blocks displaced from parts of N. America Formation of an accreted terrane ^í'V Formation of an accreted terrane (c) Accreted isEand arc Approaching Arc or Microcontinent Trench Fragment of continent Continental crust Ocean crust Fig. 20.21a Accreted Microplate Terrane Fig. 20.21c Collision ■ Fig. 20.21b Microplate terranes Added to Western North America Over the Past 200 Million Years Aŕter Nutchiiuw J99Z-19Í3 Fig. 20.22 Wilson Cycle ■Supercontinent Cycle (500 million years) -:4-i-i-'.-'l-'.^A ^ ľjJjKjJJ!V I;! ^ ľjSXjK 'y ,1,1i,,i iii' ■ !_■_■ INJ,!. :i" "r"i""" 1) Initial Rifting 2) Rafting of Continents 3) Subduction of oceanic crust at continental margins j ■. .■. .■■■. .-. j ■. ■. .■ -j ------ r-.-.ŕ.-x-. \ ^ .■ i r. .■.■. ■ ^ .■ 4) Continental collision K-OjOSING RhmNaNT^y^ OraiN Basin 5^Ž Ocean hacta adnosl ttased; cdjlslnn aboutto occur F - Collision Obocency (fight continent ovHilriss Wtccintinrait; «man baslt ctoifll. G - Pin»laine& Mountain Mountains wwhd 1o em teveH; tadonir. stabil 1y again \ C - PuauwiD MnwTAM Y-Ů * K -A * y -A J--------------" ■ i ■! " | y F - Cm.i.iftiťiPi í>Rťi^a?ií:v A - SľAiu CktJiTnn 7T-Vt4 * P A ľ ľ-| i Y-l * Pi^íJ *-J ^>*-ŕ J"J *->*-ŕ | ' F*ľ KH" V-b' F-k" VH ' V-b' IŤťJ •■ > ■ f ■■■ f IVJ i >■■ t li Wilson Kabi.v Hiettnli ť -Fial Ottaw Bjuw fgßt* ^* +^F^PT + , kttpi/Zg «ill^.jmrj jsdu/Flchtet/WiJsrti/iwlIsPíidid .html Rock assemblages and plate tectonics Each plate tectonic environment produces a distinctive group of rocks. By studying the rock record of an area, we can understand the tectonic history of the region. Tectonic QFL Distribution QFL Composition Diagram Quartz Subartrasi Quit! blŕthlc Feldspar Rock fLitfticJ Fražments stable Continental Craton Rift Basin (Divergent Plate Boundary) Recycled Orogen (Cont in ental-Co nti n ental or Continental-Volcanic Convergent Plate Boundary) Volcanic Island Arc (Convergent Plate Boundary) me\Or! ige_\Xzl Ä|B-jüg|iL ÍŽEI £2 nĹlSL Hg.\Hz mt I Sei The QFL Distribution Of Sedimentary Rocks In Various Tectonic Regimes FifiST Twb Stages in the Bjftin6 Process Stage B in Wilson Cycle * Wilson Home Page * Stage fc * Igneous Home Page • Volcanos may be fissure type or conduit type • Bimodal association: felslc [alkafinej + maflc [tholelltlc) KM 3" ■?■ Horst Graben Volcano: mafic If from not spot Felsk if from melting of continental crust ^ * -r ^ ^ -j ^ V -1 v s ľ s v ^ -4 ■^ - i /Normal faults ■ -7 -i Hot Spot /Thermal Doming *4 ^ -7 -4 ■? -i - -> V -L V -1 -----T" -í L ^ ^ -} -i ^ "7 -i V J ^ f -J 'J Ľ M -T lV^-7 1/xJ-T IŕxJ-T f^J-í ^ ^ Felsic batfiolíths from fractioiLdJ melting or lower continental crust v -\ KW 3- Contlnental Terrace (hinge zone)- Axlal Rift Alluvial fan ST lake deposits Foundering of Rift Valley / Marine Invasion 527� •Continental Rifting (figure 6.15, p 143) •Upwarping •Rift Valley »Triple Junction Bulge over rising mantel plume Development of 3 radial rifts Red Sea Gulf of Aden East African Rift »Aulacogen Third Stase in the Sifting Process Stage C in Wilson Cycle Newly Opening Ocean Basin f~ Eariy DiveTgent Margin Sediment Wedge jiŕ#.*^TVa>KeressMŕ bereh ani^^ Mid Oceanic Rift (Generating Ophlollte Suite) ^\ Shelf Mo Axial rfrr on this side Early Divergent Margin First Two Stages Wilson Home Pagt Fourth Stage in the Rutins Process Stage D in Wilson Cycle Generation of mafic oceanic crust Full Divergent Margin 3 QuArrz Volcanic Arc Systém (Rock Distributions) Paired Metamorphism Barr avians—^*~-^ Bluest h ist Fdlaspsr Lithics Ijthic rich carbonate reef v sediments lithic rich sediments Bluésohist II - Generation of intermediate/felsic igneous rocks by fractional melting in a subduction - zone stage E-G Stage E RGmnant OcGan Baiin Volcanic Arc Stage F ivection Cell Stage I Stabilized Continental Craton KM 3- Horst Graben *->l 1 yml vk|1 tI-t ľij-f i/ij-r kj 4 f-7-J "* -J -1 f-ř-i ■3-H Vsi. H v si ^ v si M M-f lrj-f kj M^ltřNor V si /^v A Ju 1 v/ll ŕ *1 ■f -a/-' 7r4ii-i -Wjy\- Volcano: mafic if from hot spot. Felsic ir rrom melting of continentigl crui Normal Faults -r _, Ä f ^ -i M f lij 1 ľi| 1 ři| í ř^ 1 k-J -7-J f-J-1 f-T-i -1-T4 1 -T-í 1 -T-i 4 |/-j ^ y^M iiHill v .j M V s) V j -r ki|-f 1/ J ^ kíl ■* k-J -r kíl ■* k-j Hot Spot/ Thermal Doming -Feist batholiths from fractional melting or lower continental crust KU J1 Continental Terrace (hinge zone) Axial Rift Alluvial fan & lake deposit?, T i "T -J 4 "T V si ^ V -4 >l V si "J -T -í ■* -T -Í. "Í V si H" V si ^ ■4 ^ v -4 *» T Foundering of Rift Valley / Marine Invasion Early Divergent: Margin Sediment Wedge i -r ir,(Errate " ■*■'"' TOldriftvDtano Newly Opening Ocean Basin ľ------------------------■*■------------------------^ Mid Oceanic Rift (Generating Ophiolite Suite) No A>ial rift on this^ide ;jT; ^*JIU 11 IL IfUILiJIILI k *J™^ Í4< V ■* ^ If -J * J Y-a II ft* v-t v (jí V-i H vjV ř.jH i-í k i V ki -f *t|* fc i -I k^ -í * -J * i7h »47|l v"** V -J*U V-l* V ij -r lr ^ -F K^ T ŕ t| T lŕ ^ Ml -f ľd -ť M -í b^ ■* Ľ 4 * -i-L- * -3-fc * t 11^ VJ^V-A-1 Early Divergent Margin 4 ■* * -j 4 4 -j -1 -f ^ * T -, (ŕ J H V-4i H V 4 "H M (-ŕ Ir-í-ŕ y-á V t -i -t L ■L * -j 4 ^ "7-* ^ T * ■*?■■* Ti i II___niwArnAnt ÍV d ■-. ľ.-i i »-. INTRODUCTION TO QFLQFL stands for Quartz, Feldspar, Lithics Sedimentary rocks are classified on the basis of the texture (grain size) of the rock, and composition. The t i only concerned texture, using the ^ q. But any full rock name must specify both texture and composition. Thus, an arkose sandstone is a rock of sand sized particles, with a high percentage of those particles being feldspar. It might seem that an unlimited variety of particles could end up in a sedimentary rock. After all, there are over 6000 known minerals. In addition, any incompletely weathered piece of igneous, sedimentary, or metamorphic rock can also be found in a sedimentary rock. A composition classification could become very complicated if all of these different particles were considered. But in most cases rock composition can be defined by four compositional components: >» Quartz >» Feldspar >» Lithic fragments (including rock fragments and mineral grains other than quartz) >» Matrix (a catchall for the silt and clay grains that cannot be easily seen by eye). QFL Diagram: The QFL diagram is to the right. Observe the following: »» Quartz is at the top, feldspar on the lower left, and lithics on the lower right It is always done this way. »» The ternary diagram is divided into 5 fields, here color coded. The boundaries among the fields, left and right, are at the 50%> boundary, and up and down at the 75%> and 90%> boundaries. »» As you travel toward any apex the quantity of Q, F, or L increases accordingly, with 100%) being, of course, right at the apex. »» Notice that as we travel vertically the amount of quartz in the rock increase: and at the 90%> boundary and above the rock has so much quartz the rock becomes "quartz something", such as a quartz sandstone or quartz conglomerate. »» The lower two fields contain rocks that are felspar (red) or lithic (blue) rich. That is, these rocks have more than 25%> feldspar or lithics, that is, 25-100%) feldspar or lithics. Rocks with this composition have such names asfeldspathic (arkosic) sandstone (both terms are used interchangably) and lithic sandstone. »» Remember that all feldspar and lithic fragments are going to weather and disappear (to shale or dissolved minerals), leaving only quartz. On the QFL diagram, however, we can only plot the abundance of sand (or larger) particles of various compositions. So, on this diagram, as feldspar and lithics weather the composition of the remaining sandstone migrates toward the quartz apex. No matter where you start on the diagram the sediment is going to evolve in almost a straight line right to the top. 3, a QFL Composition Diagram Quartz kpuutz íubailras Feldspar Rock TLitriicJ Fragments One of the things we are very interested in is how close the sediment has gotten along its path of evolution. This is the concept of sediment maturity. Thus, above the arkosic and lithic fields, but below the quartz field are two more fields, subarkosic and sublithic. Rocks in these fields have between 10-25 % feldspar or lithics and are thus farther along in their evolution toward pure quartz than feldspathic or lithic rocks. »» In other classsification systems, the boundaries among the fields sometimes differ from this one, and there may be more fields than 5 laid out. It all depends on what the geologist wants to do with them. But for this site we will always have these five fields, in these five places. »» Observe that a composition plotted somewhere in the middle of the QFL indicates a mixed composition. For example, the composition of "A" to the right is about 50% quartz, 35% feldspar, and 25% lithics (ternary with percent numbers). We could just call it an arkose since it falls in the feldspar field, but it would be more accurate to indicate that a lot of lithics are present too. Such a name, following the :s, is lithic, feldspathic, quartz Quartz Feldspar 5Ď RocK fLíthicJ Fragments A Tectonic Rock Cycle. The diagram below takes the outline tectonic rock cycle and explores it into its details and rationalle. The Roman numerals in yellow circles are clickable and will take you to more detailed descriptions of the processes operating at that stage. Clicking the igneous rock names will take you to samples. Clicking the tectonic regime names (in blue script) will take you to a stage in the ^ e where the processes are taking place. fthyolitcj ( Schist J|| ( Gneiss ) Dforitc/ ^ fiabbro/ Basalt Öctanic Ctuit iTUettlvtrcÄ AHirrtkuntz/Wiatciite. f Anorthosite v .__ j I Blue-*>. K schist V ) \Y) 1 Omen 2 Hi rich 5 Öliwirir rich Fnuttíoímtŕíí Mantle Diver