Kev Sib Txuas Lus Metamorphism thiab Piv Txwv yog dab tsi?
Kev hloov pauv yog txheej txheem ntawm kev hloov pob zeb qub (protolith) mus rau hauv pob zeb tshiab vim muaj kev hloov pauv ntawm lub cev thiab tshuaj lom neeg hauv lub ntiaj teb lub plhaub. Qhov kev hloov pauv no feem ntau yog cuam tshuam los ntawm qhov kub thiab txias, siab, thiab qhov muaj cov kua (piv txwv li, dej kub, muaj ntau yam minerals). Ib qho ntawm cov hom kev hloov pauv yooj yim tshaj plaws kom nkag siab vim nws txoj hauv kev yog "hauv zos" thiab nws qhov chaw kub yog qhov tseeb yog kev sib cuag metamorphism. Kev sib cuag metamorphism tshwm sim thaum lub pob zeb nyob ib puag ncig raug "ci" los ntawm cua sov los ntawm magma uas nkag mus rau hauv lub ntiaj teb lub plhaub. Tsab xov xwm no tham txog lub ntsiab lus ntawm kev sib cuag metamorphism, cov txheej txheem uas nws tshwm sim, cov yam ntxwv ntawm cov pob zeb, thiab cov piv txwv feem ntau.
Nkag siab txog kev sib cuag metamorphism
Kev hloov pauv ntawm cov pob zeb sib txuas yog kev hloov pauv uas tshwm sim feem ntau vim yog qhov kub thiab txias nce ntxiv vim yog magma nkag los (piv txwv li, batholith, laccolith, sill, lossis dike) uas nkag mus rau hauv cov pob zeb uas twb muaj lawm. Thaum cov magma kub heev nkag mus thiab tom qab ntawd txias qeeb qeeb, qhov kub kis mus rau cov pob zeb uas nyob ib sab (pob zeb teb chaws). Cov pob zeb ze ntawm qhov kev sib txuas yuav raug "cua sov" heev, ua rau lawv cov zaub mov hloov pauv, rov tsim dua, lossis teb rau cov zaub mov tshiab uas ruaj khov ntawm qhov kub siab dua.
Tus yam ntxwv tseem ceeb ntawm kev sib txuas metamorphism yog qhov kub thiab txias tswj hwm qhov siab. Kev nyem feem ntau tsis siab heev vim tias cov txheej txheem feem ntau tshwm sim ntawm qhov tob tob mus rau nruab nrab ntawm cov pob zeb. Yog li ntawd, cov pob zeb metamorphic uas tshwm sim los ntawm kev sib txuas metamorphism feem ntau muaj cov qauv tsis muaj nplooj (tsis muaj txheej), tsis zoo li ntau lub pob zeb metamorphic hauv cheeb tsam, uas feem ntau ua nplooj vim yog kev nyem.
Cov txheej txheem ntawm kev sib cuag metamorphism tshwm sim li cas?
Cov txheej txheem ntawm kev sib cuag metamorphism tuaj yeem sau ua ntau theem:
1. Kev nkag mus ntawm Magma
Cov pob zeb magma nce los ntawm sab hauv lub ntiaj teb thiab nkag mus rau hauv cov kab nrib pleb lossis qhov chaw hauv lub crust. Cov kev nkag mus no tuaj yeem ua cov pob zeb magma loj (batholiths) lossis cov ntawv nyias nyias (dikes/sills).
2. Kev hloov cua sov mus rau cov pob zeb sab
Vim yog qhov sib txawv ntawm qhov kub thiab txias heev, cua sov txav mus los ntawm magma mus rau pob zeb nyob ib puag ncig los ntawm kev sib kis thiab qee zaum nrog kev pab los ntawm cov kua dej hydrothermal.
3. Kev rov ua dua tshiab thiab kev tsim cov zaub mov tshiab
Cov zaub mov qub yuav tsis ruaj khov thaum kub tshiab. Cov pob zeb siv lead ua yuav loj hlob tuaj (recrystallization) lossis tsim cov zaub mov sib txawv los ntawm kev tshuaj lom neeg. Piv txwv li, av nplaum thiab lwm yam zaub mov zoo hauv cov pob zeb sedimentary tuaj yeem hloov mus ua cov zaub mov metamorphic ruaj khov dua.
4. Kev tsim cov metamorphic aureole
Thaj chaw uas raug cua sov cuam tshuam nyob ib puag ncig qhov nkag mus hu ua metamorphic aureole. Lub aureole no feem ntau qhia txog thaj chaw hloov pauv: ze tshaj plaws rau qhov nkag mus, qib kev hloov pauv siab tshaj plaws, tom qab ntawd txo qis thaum koj tsiv mus.
5. Kev txias thiab "khov" ntawm cov khoom metamorphic
Thaum qhov kev nkag mus txias lawm, qhov kub thiab txias yuav txo qis thiab cov kev hloov pauv ntawm cov minerals yuav tsis hloov pauv lawm. Cov pob zeb metamorphic uas tshwm sim los ntawm qhov no "tau kaw cia" ua cov ntaub ntawv geological ntawm qhov kev nkag mus.
Cov yam ntxwv ntawm kev sib cuag metamorphism
Qee cov yam ntxwv pom muaj nyob rau hauv kev sib cuag metamorphism:
- Hauv zos thiab nyob ib puag ncig qhov nkag: tus qauv faib tawm ua raws li lub cev ntawm qhov nkag, tsim ib lub aureole.
- Tswj los ntawm qhov kub thiab txias siab: kev siab tsis zoo li thaj tsam metamorphism.
- Cov qauv feem ntau tsis muaj nplooj: nws tsim ntau lub pob zeb loj xws li hornfels lossis marble.
- Cov kev hloov pauv ntawm cov zaub mov kub siab: cov tsos ntawm qee cov zaub mov ntsuas uas qhia tias kub nce ntxiv.
- Feem ntau cuam tshuam nrog kev ua haujlwm hydrothermal: cov kua kub tuaj yeem ua kom cov tshuaj tiv thaiv sai dua thiab txav cov tshuaj lom neeg.
Cov pob zeb uas tshwm sim los ntawm kev sib cuag metamorphism (piv txwv)
Nov yog qee cov piv txwv ntawm cov pob zeb uas feem ntau tsim los ntawm kev sib cuag metamorphism, nrog rau lawv cov protoliths thiab cov yam ntxwv.
1. Hornfels (pob zeb horn)
Hornfels yog ib lub pob zeb metamorphic uas feem ntau sib txuas, feem ntau yog tsim los ntawm cov pob zeb sedimentary zoo li shale lossis siltstone. Vim tias nws raug cua sov sai thiab tsis muaj kev nyem ntau, hornfels muaj cov qauv compact, tawv thiab cov pob zeb zoo. Lub pob zeb no feem ntau zoo li "ci," thiab nws cov pob zeb tawg tuaj yeem ntse.
– Cov protoliths dav dav: shale, av nkos, siltstone
- Yam ntxwv: tsis muaj nplooj, du, tawv, xim yuav tsaus ntuj
- Ib puag ncig: ze rau magma kev nkag mus rau hauv
Hornfels feem ntau yog ib qho pov thawj tseeb tias thaj chaw ntawd tau ntsib cua sov heev los ntawm kev nkag mus.
2. Pob zeb marble
Marble yog tsim los ntawm kev hloov pauv ntawm limestone lossis dolostone. Thaum kub siab, cov calcite lossis dolomite minerals hauv limestone recrystallize rau hauv cov crystals loj dua, interlocking. Yog li ntawd, marble feem ntau muaj cov tsos crystalline thiab tuaj yeem polished zoo.
– Cov protoliths uas feem ntau pom: limestone, dolostone
– Yam ntxwv: tsis muaj nplooj, siv lead ua, tshuaj nrog kua qaub (rau calcite marble)
- Siv: cov khoom siv hauv tsev, cov duab puab, cov khoom dai kom zoo nkauj
Thaum sib cuag nrog cov metamorphic aureoles nyob ib puag ncig cov intrusions, limestone tuaj yeem hloov pauv mus rau marble geologically sai.
3. Quartzite
Quartzite yog tsim los ntawm cov pob zeb quartz sandstone. Kev cua sov ua rau cov pob zeb quartz sib xyaw ua ke thiab rov ua dua tshiab, ua rau pob zeb tawv heev. Hauv quartzite, cov ciam teb ntawm cov pob zeb feem ntau "ploj mus" thaum cov pob zeb tshiab sib xyaw ua ke.
– Cov protolith feem ntau: quartz sandstone
– Yam ntxwv: tawv heev, tsis muaj nplooj, quartz dominant
- Siv: pob zeb sib xyaw, pob zeb ua vaj tse, qee cov pob zeb kho kom zoo nkauj
Kev sib cuag metamorphic quartzite feem ntau tshwm sim thaum muaj kev nkag mus rau hauv lub quartz sandstone chav nyob ze.
4. Skarn (ib qho piv txwv ntawm kev sib cuag metamorphism uas muaj cov kua dej)
Cov pob zeb skarns yog cov piv txwv tseem ceeb vim tias lawv qhia tau tias muaj zog heev uas cuam tshuam nrog cov kua dej, tshwj xeeb tshaj yog thaum cov magma nkag mus cuam tshuam nrog cov pob zeb carbonate (limestone/dolomite). Cov kua kub uas muaj silica thiab cov hlau ntau tuaj yeem ua rau muaj cov tshuaj tiv thaiv metasomatic, tsim cov zaub mov xws li garnet, pyroxene, thiab wollastonite, feem ntau cuam tshuam nrog cov zaub mov ore.
- Cov protolith dav dav: pob zeb carbonate + kev cuam tshuam ntawm magma intrusion
– Yam ntxwv: cov zaub mov calc-silicate (garnet/pyroxene), feem ntau cuam tshuam nrog cov khoom siv ore deposits
– Tus nqi lag luam: tej zaum yuav muaj Cu, Fe, W, Zn, Pb, thiab lwm yam.
Skarn feem ntau yog lub hom phiaj rau kev tshawb nrhiav vim nws muaj peev xwm nqa cov khoom siv nyiaj txiag.
5. Pob zeb Calc-silicate
Yog cov pob zeb sedimentary muaj cov carbonate thiab av nplaum/quartz sib xyaw, kev sib txuas metamorphism tuaj yeem tsim cov pob zeb calc-silicate nrog cov zaub mov xws li diopside, epidote, tremolite, lossis vesuvianite. Cov hom no feem ntau tshwm sim hauv aureoles nyob ib puag ncig cov intrusions uas nkag mus rau hauv cov txheej sedimentary ntawm ntau yam sib txawv.
– Protolith: cov av sib xyaw ua ke ntawm carbonate thiab silicate
- Yam ntxwv: nplua nuj nyob rau hauv calcium silicate minerals, ntsuab mus rau xim av hauv xim
- Cov ntsiab lus: thaj chaw ze ntawm cov chaw nkag, feem ntau nyob ib sab ntawm marble lossis skarn
Piv txwv ntawm kev sib cuag metamorphism geological ib puag ncig
Kev sib cuag metamorphism tuaj yeem tshwm sim hauv ntau qhov chaw tectonic, tab sis feem ntau pom muaj nyob rau hauv:
- Cov kab hluav taws kub thiab cov cheeb tsam subduction: ntau qhov magma nkag mus rau hauv lub ntiaj teb nce thiab khov kho hauv lub crust.
– Thaj chaw Plutonic: ib thaj chaw uas muaj cov pob zeb igneous xws li granite nyob hauv.
- Cov chaw nkag tsis tob: cov kwj deg thiab cov sills uas ua kom cov pob zeb nyob ib sab sov ntawm qhov ntsuas nqaim dua.
Hauv daim teb, cov kws tshawb fawb txog av feem ntau paub txog kev hloov pauv ntawm pob zeb los ntawm kev hloov pauv ntawm hom pob zeb nyob ib puag ncig qhov nkag mus. Piv txwv li, los ntawm shale deb ntawm qhov nkag mus rau hornfels ze ntawm qhov nkag mus; lossis limestone mus rau marble hauv thaj chaw sib cuag.
Kev sib piv sai: kev sib cuag metamorphism vs regional metamorphism
Yog li kom tsis txhob tsis meej pem, ntawm no yog qhov sib txawv luv luv:
- Kev hloov pauv ntawm kev sib cuag: qhov kub thiab txias tseem ceeb, nyob ib puag ncig qhov nkag mus, feem ntau tsis muaj nplooj, tsim cov aureoles.
- Kev hloov pauv hauv cheeb tsam: cuam tshuam los ntawm qhov kub thiab txias + siab siab hla thaj chaw dav (piv txwv li, roob cuam tshuam), kev hloov pauv dav dav (schist, gneiss), qib kev hloov pauv sib txawv ntawm thaj chaw.
Kev kaw
Kev hloov pauv pob zeb uas tshwm sim los ntawm kev kub hnyiab nyob ib puag ncig magma. Vim tias nws kub thiab nyob hauv thaj chaw, qhov kev hloov pauv no tsim cov pob zeb uas feem ntau tsis muaj nplooj thiab tsim cov pob zeb hloov pauv nyob ib puag ncig qhov kev nkag mus. Piv txwv ntawm cov pob zeb uas feem ntau tsim muaj xws li hornfels, marble, quartzite, thiab cov pob zeb sib txawv xws li skarn thiab calc-silicate. Ntxiv rau qhov tseem ceeb rau kev nkag siab txog keeb kwm geological ntawm ib cheeb tsam, kev hloov pauv pob zeb kuj muaj txiaj ntsig zoo, tshwj xeeb tshaj yog thaum nws los txog rau kev tsim cov khoom siv minerals muaj nqis, xws li cov nyob hauv skarn systems.
Yog tias koj xav tau, kuv kuj tuaj yeem ntxiv ib daim duab qhia txog metamorphic aureole (cov cheeb tsam los ntawm ze ntawm qhov nkag mus rau deb), lossis tsim ib qho version ntawm tsab xov xwm no uas tsom mus rau cov piv txwv Indonesian ntau dua.
