Lub ntiaj teb pob zeb yog nplua nuj nyob rau hauv natural resources, uas minerals thiab organic minerals yuav txawv nyias. Cov neeg siv lawv nyob rau hauv ntau yam teb - los ntawm cov roj (roj, thee, roj) mus rau kev tsim kho (piv txwv li, ntsib nrog marble thiab granite) thiab tsim ntau yam khoom tsim nyog nyob rau hauv lub neej txhua hnub. Ib qho kev pab yog pob zeb gneiss.
Definition
Gneiss feem ntau hu ua metamorphic, uas yog, tsim nyob rau hauv lub plab hnyuv ntawm lub ntiaj teb, pob zeb. Metamorphism yog to taub raws li kev hloov ntawm sedimentary thiab igneous natural mineral formations raws li kev hloov nyob rau hauv lub cev thiab tshuaj tej yam kev mob (kub, siab, raug rau ntau yam roj thiab dej daws). Cov txheej txheem zoo li no tshwm sim vim muaj kev hloov pauv hauv lub ntiaj teb crust thiab lwm yam txheej txheem tshwm sim hauv lawv. Yog li ntawd, ntau yam kev hloov pauv tshwm sim thiab cov pob zeb metamorphic raug tsim. Gneiss feem ntau tshwm sim los ntawm qhov sib txawv ntawm qhov sib luag-schistose, feem ntau ua kom zoo nkauj zoo nkauj.
Cov nplej loj ntawm cov ntxhia feem ntau yog ntau dua 0.2 hli. Cov ntaub ntawv granular-crystallineformations yog nplua nuj nyob rau hauv feldspar thiab feem ntau yog sawv cev los ntawm quartz, muscovite, biotite thiab lwm yam minerals. Ntawm cov xim, lub teeb ntxoov ntxoo predominate (grey, liab thiab lwm yam).
Gneiss yog ib qho ntawm cov pob zeb metamorphic tshaj plaws, yog cov khoom siv zoo heev thiab ua tiav hauv kev tsim kho. Nws zoo li ib qho sib npaug sib npaug nrog ib qho ntxhib thiab tsis sib xws. Muaj qhov loj durability, hloov loj amplitudes ntawm kub. Cov khoom siv lub cev thiab cov khoom siv kho tshuab txiav txim siab mus ntev, txhim khu kev qha thiab zoo nkauj hauv kev tsim kho, tsev thiab pavement cladding, thiab tsim sab hauv.
Terminology issue
Nyob hauv zej zog kev tshawb fawb, muaj kev sib cav txog cov lus nug uas cov pob zeb gneiss belongs rau. Qee cov kws tshawb fawb (Levinson-Lessing, Polovinkina, Sudovikov) ntseeg tias quartz yuav tsum nyob ntawm no. Lwm cov kws tshawb fawb (Saranchina, Shinkarev) muab tso rau qhov sib txawv ntawm qhov pom, raws li cov pob zeb muaj nyob hauv feldspars, thiab kuj suav nrog quartz. Ntawd yog, nyob rau hauv qhov kev xaiv thib ob, lub xub ntiag ntawm quartz tsis tsim nyog.
Txawm li cas los xij, thawj qhov kev txhais lus yog nyob ze rau nws qhov kev txhais lus qub, thaum lo lus no tsuas yog txhais tau hais tias tsuas yog shales sib xws hauv cov ntxhia hauv cov ntxhia hauv granites. Ntawd yog, quartz tseem yog typomorphic, lub ntsiab lus ntxhia hauv cov ntsiab lus ntawm gneisses.
Hypotheses txog kev kawm
Lub hauv paus chiv keeb ntawm lub pob zeb gneiss tsis to taub tag nrho txawm nyob rau hauv peb lub sij hawm, txawm hais tias nws muajob peb lub kaum os kev xav, nrog rau ntau qhov chaw sau ntawv uas kov rau lub ntsiab lus no. Txawm li cas los xij, tag nrho cov kev txiav txim sib sau ua ke hauv qee qhov kev xav. Piv txwv li, qhov tshwm sim ntawm gneisses yog txiav txim los ntawm cov txheej txheem ntawm sib sib zog nqus metamorphism ntawm ntau pob zeb.
Qee tus kws paub txog tsiaj txhu suav tias gneiss yog cov tawg ntawm lub ntiaj teb primordial crust, uas npog lub ntiaj teb thaum lub sij hawm txias thiab hloov lub xeev ntawm aggregation los ntawm fiery-kua rau khoom. Kuj tseem muaj qhov kev xav tias cov no yog cov pob zeb tsis muaj zog, uas, raws li qhov tshwm sim ntawm metamorphism, tau txais txheej txheej. Tseem muaj lwm tus xav tias gneisses yog cov tshuaj lom ntawm cov dej hiav txwv primordial, uas crystallized nyob rau hauv siab atmospheric siab los ntawm superheated dej. Tseem muaj lwm tus pom lawv li pob zeb sedimentary uas tau hloov pauv ntau txhiab xyoo nyob rau hauv lub zog ntawm lub ntiaj teb kub, siab thiab dej hauv av.
Muaj lwm qhov kev xav, raws li qhov gneisses yog cov pob zeb sedimentary uas crystallized thaum lub sij hawm los yog sai tom qab lawv deposition nyob rau hauv lub ntiaj teb crust. Nws ntseeg tau tias qhov kev tsim ua zoo tshaj plaws ntawm gneiss hauv keeb kwm ntawm lub ntiaj teb tau tshwm sim txog 2.5-2.0 billion xyoo dhau los.
Kev sib xyaw thiab qauv
Gneiss yog ib lub pob zeb uas muaj ib qho kev ntxhib los mos zoo nkauj vim muaj kev sib hloov ntawm lub teeb thiab tsaus nti. Cov xim feem ntau yog lub teeb. Cov khoom tseem ceeb: quartz, feldspar thiab lwm yam.
Cov tshuaj muaj pes tsawg leeg yog ze rau granites thiab shale, ntau yam. Raws li txoj cai, qhov no60-75% silicic acid, 10-15% alumina thiab ib qho me me ntawm hlau oxide, txiv qaub, Mg, K, Na thiab H2O.
Lub cev tsis muaj zog yog nyob ntawm tus qauv thiab qib ntawm schistosity. Cov yam ntxwv ceev yog 2600-2900 kg / m3, qhov feem pua ntawm pore ntim hauv tag nrho cov ntim yog 0.5-3.0%.
Raws li cov khoom ntxhia, nws yog ib txwm ua kom paub qhov txawv ntawm biotite, muscovite gneisses thiab lwm yam. Los ntawm cov qauv, lawv yog, piv txwv li, ntoo zoo li, spectacle, daim kab xev.
Raws li hom pob zeb thawj, muaj kev faib ua para- thiab orthogneisses. Thawj tshwm sim los ntawm kev hloov ntawm cov pob zeb sedimentary; qhov thib ob - vim yog kev hloov kho ntawm igneous (feem ntau yog volcanogenic) pob zeb.
Ib yam ntxwv ntawm gneiss pob zeb yog schistosity, uas muaj cov yam ntxwv sib txawv. Nws yog ib qho seem ntawm cov ntaub pua tsev ntawm cov pob zeb sedimentary, lossis yog kev nkag mus.
Ntau yam
Kev faib cov gneisses rau ntau hom yog vim muaj ntau haiv neeg ntawm cov mineralogical thiab elemental muaj pes tsawg leeg, qib ntawm cov nplej loj (cov yam ntxwv nta) thiab kev npaj ntawm cov nplej hauv pob zeb (cov yam ntxwv ntawm cov ntaub ntawv).
Raws li kev hloov pauv ntawm cov pob zeb sedimentary, alumina-nplua nuj gneisses tau tsim, feem ntau suav nrog garnet thiab andalusite (siab alumina).
Pob zeb nrog porphyroblastic kev ntxhib los mos, uas feem ntau sib npaug lossis elliptical feldspar porphyroblasts (qee zaum ua ke nrog quartz) hauv ntu ntu yog pom hauv daim ntawv.peepholes hu ua spectacles.
Complex metamorphic formations ntawm cov qauv sib xyaw, nkag los ntawm cov khoom siv granite, suav nrog nws cov leeg, hu ua migmatites.
Gneiss tuaj yeem tsim los ntawm ntau cov zaub mov: biotite, muscovite, diopside thiab lwm yam. Qee hom gneiss muaj lawv lub npe, xws li charnockites thiab enderbites.
Dhau li ntawm, kev faib raws li hom thawj hom tsiaj tau dav siv. Gneiss li pob zeb tsis muaj zog yog sawv cev los ntawm orthogneisses uas tau tshwm sim los ntawm kev hloov pauv ntawm cov pob zeb tsis muaj zog (piv txwv li, granites). Nws ntseeg tau tias lawv lub hauv paus tseem ceeb yog volcanic eruptions. Paragneisses yog qhov tshwm sim ntawm qhov sib sib zog nqus metamorphism ntawm cov pob zeb sedimentary.
Kev sib raug zoo ntawm gneiss thiab granite
Gneiss yog ib lub pob zeb ntau, uas yog feldspar, quartz thiab mica. Cov khoom zoo sib xws kuj yog cov yam ntxwv ntawm granite, tab sis muaj qhov sib txawv hauv paus. Nws nyob rau hauv qhov tseeb hais tias nyob rau hauv granite tsis muaj kev faib tawm meej ntawm nws cov khoom siv. Nyob rau hauv gneiss, tag nrho cov minerals yog parallel rau ib leeg, muab nws layering. Tsis tas li ntawd, minerals feem ntau tshwm sim nyob rau hauv lub ntiaj teb crust nyob rau hauv loj daim hlau thiab txheej.
Txawm li cas los xij, muaj ntau zaus thaum lub pob zeb gneiss poob nws cov txheej txheem thiab hloov mus ua granite. Qhov xwm txheej no qhia txog kev sib raug zoo ntawm cov tsim ntuj tsim.
Qhov tshwm sim ntawm lub ntiaj teb crust
Nws yog qhov tsim nyog tias txawm tias nws qhov kev faib tawm dav, gneiss muaj ntau yam. Raws li qhov tshwm sim ntawm ntau yamcov txheej txheem, txoj kev thiab cov kev taw qhia ntawm kev sib nrig sib kev npaj ntawm nws constituent qhov chaw hloov, uas, ntawm lwm yam, tshiab minerals kuj koom los yog ib feem hloov lawv. Raws li qhov tshwm sim, ntau hom gneiss tau tshwm sim.
Gneisses muaj ntau, feem ntau ntawm cov pob zeb ntawm Precambrian lub sijhawm. Yog li, grey-gneiss deposits ntawm lub qab daus ntawm Canadian Shield yog suav hais tias yog cov qub pob zeb nyob rau hauv lub ntiaj teb no: raws li cov kws tshawb fawb, lawv muaj ntau tshaj peb billion xyoo. Txawm li cas los xij, cov pob zeb yau ntawm Cenozoic era, tsim los ntawm qhov kub thiab txias, kuj muaj ntau.
Kev faib tawm (distribution)
Lub pob zeb gneiss tawm ntawm qhov tob mus rau saum npoo, feem ntau yog nyob rau hauv cov teb chaws uas, vim muaj ntau yam txheej txheem thiab cov txheej txheem, muaj kev ua tsis tiav nyob rau hauv kab rov tav txheej txheej, lossis los ntawm kev yaig ntawm cov txheej txheem tshiab. thiab raug cov laus.
Feem ntau cov nyiaj tso cia tseem ceeb yog cuam tshuam nrog kev tawm ntawm cov crystalline hauv qab daus. Ntawm B altic Shield, qhov no yog koom pheej ntawm Karelia, Leningrad thiab Murmansk cheeb tsam, thiab txawv teb chaws - Finland.
Nyob rau hauv Lavxias teb sab Federation, gneisses feem ntau pom nyob rau hauv lub hauv paus sawb ntawm lub Ural Range, nyob rau hauv sab qab teb sab hnub tuaj ntawm Siberian Platform (Aldan ntaub thaiv npog), lub Caucasian Labino-Malkinskaya cheeb tsam thiab nyob rau hauv lub axial cheeb tsam ntawm lub uplift. lub Main Range.
Tsis tas li ntawd, txawv teb chaws, cov nyiaj tso cia yog tsom rau hauv Canadian Acasta complex, Scandinavia, ntawm Ukrainian Shield ntawm East European Platform.
Daim ntawv thov (siv) ntawm gneiss
Rock feem ntausiv los tsim cov pob zeb hauv tsev (pob zeb crushed thiab rubble), nrog rau kev ua tiav. Cov khoom siv ntuj no yog siv los ua butyl hauv daim ntawv slabs rau cov hauv paus, slabs rau cov neeg taug kev; lawv kuj tseem siv tau rau hauv kab kwj dej thiab embankments. Nws ntseeg tau tias qhov ze dua qhov kev ntxhib los mos ntawm pob zeb gneiss rau granites, lawv qhov zoo dua.
pob zeb no yog siv los tsim cov khoom tseem ceeb ntawm kev sib raug zoo: cov tsev, tuam tsev, footpaths, squares, yards.
Gneiss feem ntau yog siv los tsim kho kom zoo nkauj sab hauv thiab sab nraud ntawm cov tsev thiab cov qauv: tig mus rau phab ntsa, kab, ntaiv, pem teb thiab qhov cub.
