Kuyini i-Contact Metamorphism kanye nezibonelo?
I-Metamorphism inqubo yokushintsha idwala lokuqala (i-protolith) libe yidwala elisha ngenxa yezinguquko ezimweni zomzimba nezamakhemikhali ngaphakathi kongqimba loMhlaba. Lolu shintsho luthonywa kakhulu izinga lokushisa, ingcindezi, kanye nokuba khona koketshezi (isb., amanzi ashisayo, acebile ngamaminerali). Enye yezinhlobo ezilula kakhulu ze-metamorphism ukuqonda ngoba indlela esebenza ngayo "iyindawo" futhi umthombo wayo wokushisa ucacile yi-contact metamorphism. I-contact metamorphism yenzeka lapho idwala elizungezile "libhakwa" ukushisa okuvela ku-magma okungena ongqimbeni loMhlaba. Lesi sihloko sixoxa ngencazelo ye-contact metamorphism, inqubo eyenzeka ngayo, izici zamadwala, kanye nezibonelo ezivamile.
Ukuqonda ukuguqulwa kokuxhumana
Ukushintshashintsha kokuthintana kwenzeka ngokuyinhloko ngenxa yokushisa okuphezulu ngenxa yokungena kwe-magma (isb., i-batholith, i-laccolith, i-sill, noma i-dike) okungena edwaleni elikhona. Njengoba i-magma eshisayo kakhulu ingena bese iphola kancane, ukushisa kusakazekela edwaleni eliseduze (idwala lasemaphandleni). Amadwala aseduze nokuxhumana kokungena abhekana "nokushisa" okukhulu, okubangela ukuthi amaminerali awo ashintshe, aphinde avuseleleke, noma asabele ekwakheni amaminerali amasha azinzile emazingeni okushisa aphezulu.
Isici esiyinhloko se-contact metamorphism ukubusa kwezinga lokushisa ngaphezu kwengcindezi. Izingcindezi ngokuvamile aziphezulu kakhulu ngoba inqubo ivame ukwenzeka ekujuleni okungajulile kuya kokuphakathi koqweqwe. Ngenxa yalokho, amatshe aguqukayo avela ku-contact metamorphism avame ukuba nokuthungwa okungaxutshwe namaqabunga (okungaxutshwe namaqabunga), ngokungafani namatshe amaningi aguqukayo esifundeni, avame ukuba namaqabunga ngenxa yengcindezi eqondisayo.
Inqubo yokuguqulwa kokuxhumana yenzeka kanjani?
Inqubo yokuguqulwa kokuxhumana ingafingqwa ngezigaba eziningana:
1. Ukungena kwe-Magma
I-Magma iphakama isuka ngaphakathi koMhlaba bese ingena emifantwini noma ezikhaleni ezikuqweqwe. Lokhu kungena kungathatha isimo semizimba emikhulu ye-magma (ama-batholith) noma amashidi amancane (ama-dikes/sills).
2. Ukudluliselwa kokushisa emadwaleni aseceleni
Ngenxa yomehluko omkhulu wokushisa, ukushisa kuhamba kusuka ku-magma kuya edwaleni elizungezile ngokuqhutshwa komoya futhi ngezinye izikhathi ngosizo lwe-hydrothermal fluids.
3. Ukuphinda kusetshenziswe kabusha kanye nokwakheka kwamaminerali amasha
Amaminerali amadala awazinzile emazingeni okushisa amasha. Amakristalu angakhula abe makhulu (aphinde akhiqizwe kabusha) noma akhe amaminerali ahlukene ngokusebenzisa ukusabela kwamakhemikhali. Isibonelo, ubumba kanye namanye amaminerali acwebezelayo emadwaleni acwebezelayo angaguquka abe amaminerali azinzile kakhulu.
4. Ukwakheka kwe-aureole eguquguqukayo
Indawo ethinteke ekushiseni ezungeze ukungena ibizwa ngokuthi i-metamorphic aureole. Le aureole ivame ukukhombisa izindawo zokushintsha: eduze kokungena izinga lokuguquka liphezulu kakhulu, bese liyancipha njengoba uhamba.
5. Ukupholisa kanye "nokuqandisa" imikhiqizo eshintshashintshayo
Uma ukungena sekupholile, izimo zokushisa ziyancipha futhi izinguquko zamaminerali ziyaphela. Idwala eliguqukayo elivelayo "livalelwe" njengomlando wejiyoloji wokungena.
Izici ze-contact metamorphism
Ezinye izici ezivamile ezitholakala ku-contact metamorphism:
– Indawo ezungezile ukungena: iphethini yokusatshalaliswa ilandela umzimba wokungena, yakha i-aureole.
– Kubuswa amazinga okushisa aphezulu: ingcindezi ayinkulu njengokuguquka kwesimo sendawo.
– Ukuthungwa ngokuvamile akunawo amahlamvu: kukhiqiza amatshe amaningi amakhulu njenge-hornfels noma imabula.
– Izinguquko ezivamile zamaminerali okushisa okuphezulu: ukubonakala kwamaminerali athile abonisa ukwanda kwezinga lokushisa.
– Ngokuvamile kuhlotshaniswa nomsebenzi we-hydrothermal: uketshezi olushisayo lungasheshisa ukusabela futhi lushukumise izakhi zamakhemikhali.
Amatshe avela ekuguqukeni kokuxhumana (izibonelo)
Nazi ezinye izibonelo zamatshe avame ukwakheka ngenxa yokushintshashintsha kokuxhumana, kanye nama-protolith awo kanye nezici zawo.
1. Ama-Hornfels (i-horn rock)
Ama-Hornfels ayidwala elivame kakhulu elithintana ne-metamorphic, elivame ukwakheka ngamatshe acwebezelayo anjenge-shale noma i-siltstone. Ngenxa yokuthi lishiswa ngokushesha futhi alinawo umfutho oqondile, ama-hornfels anokwakheka okuqinile kakhulu kanye nezinhlamvu zamaminerali ezincane. Leli dwala livame ukubonakala "libhakiwe," futhi ukuqhekeka kwalo kungaba bukhali.
- Ama-protolith ajwayelekile: i-shale, i-mudstone, i-siltstone
– Izici: ukungaqambi, ukushelela, ukuqina, umbala ungaba mnyama
– Indawo: eduze kokuthintana kokungena kwe-magma
Ama-Hornfel avame ukuba ubufakazi obuqinile bokuthi indawo ibhekane nokushisa okukhulu ngenxa yokungena.
2. Imabula
Imabula yakhiwa ngokuguqulwa kwe-limestone noma i-dolostone. Emazingeni okushisa aphezulu, amaminerali e-calcite noma e-dolomite kuma-limestone aphinde aphinde abe amakristalu amakhulu, axhumene. Ngenxa yalokho, imabula ivame ukuba nokubukeka okukristalu futhi ingapholishwa kahle.
– Ama-protolith avamile: i-limestone, i-dolostone
– Izici: ezingacwebezeli, zicwebezela, ziphendula nge-asidi (uma kutholakala imabula ye-calcite)
- Ukusetshenziswa: izinto zokwakha, izithombe, imihlobiso
Kuma-aureole athintanayo azungeze ukungena, i-limestone ingaguquka ibe yi-marble ngokushesha ngokwejiyoloji.
3. I-Quartzite
I-Quartzite yakhiwa ngetshe lesihlabathi le-quartz. Ukushisa kubangela ukuthi izinhlamvu ze-quartz zihlangane ngokuqinile futhi ziphinde ziphinde zifane, okwenza idwala libe lukhuni kakhulu. Ku-quartzite, imingcele phakathi kwezinhlayiya ivame "ukunyamalala" njengoba i-fuse yamakristalu amasha.
– I-protolith evamile: itshe lesihlabathi le-quartz
– Izici: eqinile kakhulu, engenamabala, i-quartz ebusayo
- Ukusetshenziswa: i-aggregate, itshe lokwakha, amatshe athile okuhlobisa
I-quartzite exhumanayo ye-metamorphic ivame ukuvela lapho ukungena kushisa iyunithi yesihlabathi se-quartz eseduze.
4. I-Skarn (isibonelo sokushintshashintsha kokuxhumana okubandakanya uketshezi)
Ama-Skarns ayizibonelo ezibalulekile ngoba abonisa ukuguqulwa okunamandla kokuxhumana okuqhutshwa uketshezi, ikakhulukazi lapho ukungena kwe-magma kuhlangana namatshe e-carbonate (i-limestone/i-dolomite). Uketshezi olushisayo olucebile ngezinto ze-silica nezensimbi lungabangela ukusabela kwe-metasomatic, kwakha amaminerali afana ne-garnet, i-pyroxene, ne-wollastonite, evame ukuhlotshaniswa namaminerali e-ore.
– I-protolith ejwayelekile: idwala le-carbonate + ithonya lokungena kwe-magma
– Izici: amaminerali e-calc-silicate (i-garnet/pyroxene), avame ukuhlotshaniswa namadiphozithi e-ore
– Inani lezomnotho: lingaqukatha i-Cu, i-Fe, i-W, i-Zn, i-Pb, njll.
I-Skarn ivame ukuba yindawo okuhloswe kuyo ukuhlola ngenxa yokuthi inamandla okuthwala ukumbiwa kwezomnotho.
5. Amatshe anjenge-calc silicate
Uma amatshe e-sedimentary aqukethe ingxube ye-carbonate nobumba/i-quartz, i-contact metamorphism ingakhiqiza amatshe e-calc-silicate anamaminerali afana ne-diopside, i-epidote, i-tremolite, noma i-vesuvianite. Lezi zinhlobo zivame ukuvela kuma-aureoles azungeze ukungena okungena ezingqimbeni ze-sedimentary zokwakheka okuhlukahlukene.
– I-Protolith: ingxube ye-carbonate ne-silicate
– Izici: zicebile ngamaminerali e-calcium silicate, aluhlaza okotshani kuya konsundu ngombala
– Umongo: indawo eseduze nokungena, ngokuvamile eduze kwemabula noma i-skarn
Izibonelo zezindawo ze-geological ze-contact metamorphism
Ukushintshashintsha kokuxhumana kungenzeka ezimweni ezahlukene ze-tectonic, kodwa kuvame ukutholakala ku:
– Ama-arcs entaba-mlilo kanye nezindawo ezingaphansi kwe-subduction: ukungena okuningi kwe-magma kuyaphakama futhi kuqine oqweqweni.
– Indawo ye-Plutonic: indawo egcwele amatshe angena ngaphakathi njenge-granite.
– Inkimbinkimbi yokungena engajulile: ama-dike nama-sill ashisa amatshe aseduze ngesilinganiso esincane.
Emkhakheni, izazi ze-geology zivame ukubona ukushintshashintsha kokuxhumana ngokushintsha kohlobo lwedwala oluzungeze ukungena. Isibonelo, kusukela ku-shale kude nokungena kuya kuma-hornfels eduze kokungena; noma i-limestone kuya kumabula endaweni yokuxhumana.
Ukuqhathanisa okusheshayo: i-contact metamorphism vs i-regional metamorphism
Ukuze ungadideki, nansi umehluko omfushane:
– Ukushintshashintsha kokuthintana: ukushisa okubusayo, okutholakala eduze kokungena, ukungaqali kwamaqabunga okuvamile, ukwakha ama-aureole.
– Ukuguquka kwesimo sesifunda: kuthonywa izinga lokushisa + ukucindezela okuphezulu endaweni ebanzi (isb., izintaba ezithinta), ukuhluma okujwayelekile (schist, gneiss), izinga lokuguquka kwesimo sendawo liyahlukahluka ngokwesilinganiso sesifunda.
I-Penutup
Ukuguqulwa kokuxhumana yinqubo yokuguqulwa kwamadwala eyenzeka ngenxa yokushisa okukhulu eduze kokungena kwe-magma. Ngenxa yokuthi ilawulwa amazinga okushisa futhi itholakala endaweni ethile, lokhu kuguqulwa kokuxhumana kukhiqiza amatshe ngokuvamile angenawo amahlumela futhi akha i-aureole ye-metamorphic eduze kokungena. Izibonelo zamatshe avame ukwakheka zifaka phakathi ama-hornfels, imabula, i-quartzite, kanye nokwehluka okuyinkimbinkimbi njenge-skarn kanye namatshe e-calc-silicate. Ngaphandle kokuba kubalulekile ekuqondeni umlando we-geological wendawo, ukuguqulwa kokuxhumana nakho kunenani eliwusizo, ikakhulukazi uma kukhulunywa ngokwakhiwa kwama-mineral deposits ayigugu ngokwezomnotho, njengalawo asezinhlelweni ze-skarn.
Uma ufisa, ngingangeza futhi umfanekiso ohleliwe we-aureole ye-metamorphic (izindawo eziseduze nokungena kuya kude), noma ngenze inguqulo yalesi sihloko egxile kakhulu ezibonelweni zase-Indonesia.
