Umphumela Wokushisa Nokucindezela Ekwakhekeni Kwamaminerali
Ukwakheka kwamaminerali kuyinqubo yejiyoloji eyenzeka isikhathi eside kakhulu futhi ethonywa izici ezahlukahlukene zomzimba nezamakhemikhali. Phakathi kwezici ezibaluleke kakhulu izinga lokushisa kanye nengcindezi. Lezi zici zilawula ukuzinza kwamaminerali, zinqume ukuthi yiziphi izinhlobo zamaminerali ezingakhiwa, futhi zilawule ukuguqulwa kwamaminerali amadala abe amasha ngenqubo ebizwa ngokuthi i-metamorphism. Ukuqonda imiphumela yokushisa kanye nengcindezi kubalulekile hhayi kuphela kososayensi bejiyoloji, kodwa futhi nasezimayini, i-volcanoology, kanye nezifundo zemvelo, ngoba ukwakheka kwamaminerali kuhlobene eduze nezinsiza zemvelo kanye nokuguquguquka koMhlaba.
Imiqondo eyisisekelo yokwakheka kwamaminerali
Amaminerali akhiwa lapho izakhi zamakhemikhali zizihlela ngendlela ehlelekile ukuze zakhe isakhiwo sekristalu. Le nqubo ingenzeka ngezindlela eziningana, isibonelo:
1. Ukwakheka kwe-magma (ukuqandisa idwala eliyi-igneous),
2. Ukuna kwemvula okuvela esixazululweni (isb. usawoti wamaminerali noma i-calcite emanzini),
3. Ukusabela kwe-metamorphic okubangelwa izinguquko ekushiseni nasekucindezelweni,
4. Ukushintshashintsha kokushisa kwamanzi lapho uketshezi olushisayo lusabela emadwaleni.
Nakuba izindlela zihluka, izinga lokushisa kanye nengcindezi kuhlala kukhona njenge "balawuli" abayinhloko: izinga lokushisa lithinta amandla kanye nesivinini sokusabela, kuyilapho ingcindezi ithinta ubuningi, ukuzinza kwesigaba, kanye nendlela ama-athomu ahlelwe ngayo ngamakristalu.
Izinga lokushisa: isilawuli samandla kanye nesilinganiso sokusabela
Ngokuvamile, lapho izinga lokushisa liphakeme, kulapho amandla e-kinetic ama-athomu nama-ion eba makhulu khona. Lokhu kwenza kube lula ukusabela kwamakhemikhali futhi kuvumela ukwakheka kwamaminerali adinga amandla abalulekile ukuze azinze. Umphumela wokushisa ungabonakala kulezi zici ezilandelayo.
1. Izinga lokushisa linquma ukulandelana kokukristala kwamaminerali.
Ku-magma, amaminerali awaqini ngokungahleliwe. Amaminerali anamaphuzu aphezulu okukristala akha kuqala njengoba i-magma iphola. Lo mqondo uqashelwa kabanzi nge-Bowen Reaction Series, echaza ukuthi amaminerali afana ne-olivine ne-pyroxene akha emazingeni okushisa aphezulu, kuyilapho amaminerali afana ne-potassium feldspar, i-muscovite, ne-quartz ngokuvamile akha emazingeni okushisa aphansi.
– Emazingeni okushisa aphezulu, izakhiwo zamaminerali zivame ukuba lula futhi zicebile ngezinto ezifana ne-Mg ne-Fe (isibonelo: i-olivine).
– Emazingeni okushisa aphansi, izakhiwo zamaminerali zivame ukuba yinkimbinkimbi kakhulu futhi zicebile nge-silica (isibonelo: i-quartz).
Lolu chungechunge lusiza izazi ze-geology ukuhumusha umlando wokupholisa we-magma, kanye nokulinganisa izimo lapho amatshe angenawo umoya akhiwa khona.
2. Izinga lokushisa lithinta ukuqina kwamaminerali
Amaminerali anezinga elithile lokushisa "lokuzinza." Uma izinga lokushisa lishintsha ngale kwalokhu mkhawulo wokuzinza, amaminerali angabola noma asabela ukuze akhe amaminerali amasha. Isibonelo, amanye amaminerali anamanzi (lawo aqukethe amanzi esakhiweni sawo sekristalu) awazinzile emazingeni okushisa aphezulu ngoba amanzi ayakhishwa, okubangela ukuthi amaminerali ashintshe isigaba.
3. Izinga lokushisa lisheshisa ukuguquka kwesimo
Ku-metamorphism, ukwanda kwezinga lokushisa kwenza kube lula ngama-athomu ukuhamba nokuzihlela kabusha. Lokhu kuvumela ukwenziwa kabusha kwekristalu, ukwakheka kwamakristalu amasha, azinzile. Isibonelo, idwala elicebile ngobumba lingaguquka libe yi-slate, bese kuba yi-phyllite, bese kuba yi-schist, bese ekugcineni kube yi-gneiss njengoba amazinga okushisa e-metamorphic ekhuphuka.
4. Izinga lokushisa linomthelela ezinhlelweni zamanzi ashisayo
Uketshezi olushisayo oluhamba phakathi kokuqhekeka kwamadwala lungancibilikisa izakhi ezithile futhi luzenze zibe yingozi njengoba izinga lokushisa lehla. Lena indlela ebalulekile yokwakheka kwamaminerali e-ore njenge-quartz, i-chalcopyrite, i-sphalerite, namanye amaminerali e-sulfide avame ukuhlotshaniswa namadiphozithi egolide nethusi.
Ingcindezi: umlawuli wesakhiwo samaminerali kanye nesigaba
Uma izinga lokushisa lisebenza "njengomshayeli wokusabela," khona-ke ingcindezi isebenza "njengamandla esakhiwo." Ingcindezi eMhlabeni iyanda ngokujula ngenxa yesisindo sezingqimba zamatshe ezimbozekile. Ingcindezi ithinta amaminerali ngezindlela ezihlukile kakhulu.
1. Ukucindezela kunquma ukuma kwesakhiwo sekristalu
Uma kunengcindezi ephezulu, amaminerali avame ukwakha izakhiwo ezixineneyo (ubuningi obukhulu). Ama-athomu ahlanganiswa eduze ukuze abhekane nezimo ezicindezelayo. Ngenxa yalokho, amaminerali akhiwe ekujuleni okukhulu avame ukuhluka kulawo angaphezulu, yize ukwakheka kwawo kufana.
Isibonelo esidumile ushintsho esimweni sekhabhoni:
– I-Graphite izinzile uma ingcindezi iphansi,
– Amadayimane azinzile uma ecindezelekile kakhulu, ngokuvamile embotsheni yoMhlaba.
Lo mehluko uchaza ukuthi kungani amadayimane akheka ekujuleni komhlaba bese ekhuliswa ngemisebenzi ethile yentaba-mlilo (isib. amapayipi e-kimberlite).
2. Ingcindezi idlala indima ekuguqukeni kwesimo sesifunda
Ukuguqulwa kwesimo sesifunda kwenzeka lapho indawo enkulu ibhekana nokucindezeleka okukhulu ngenxa yokushayisana kwamapuleti e-tectonic. Lokhu kucindezela kungadala ukugcwala kwama-foliation (ukubekezela) emadwaleni e-metamorphic njenge-schist ne-gneiss. Amaminerali e-lamellar njenge-mica avame ukuhambisana ngokuhambisana ngenxa yokucindezela okuqondisiwe, okuholela ekuthungeni okufana neshidi.
3. Ukucindezela koketshezi nakho kunethonya
Ngaphezu kwengcindezi ye-lithostatic, kukhona ingcindezi yoketshezi (ingcindezi ye-pore) evela koketshezi noma amagesi ngaphakathi kwe-pores yamadwala. Ingcindezi yoketshezi ingasheshisa ukusabela kwe-metamorphic futhi ishintshe amaminerali ngokuncibilika kanye nokuna kabusha. Kwezinye izimo, ingcindezi ephezulu yoketshezi ingabangela ukuqhekeka, ivule izindlela ezintsha zoketshezi olushisayo, futhi ibangele ukwakheka kwamaminerali emithanjeni.
Ukusebenzisana kwezinga lokushisa kanye nokucindezela: isihluthulelo sendawo yokuzinza kwamaminerali
Izinga lokushisa kanye nokucindezela akuvamile ukusebenza kodwa. Eqinisweni, amaminerali akha ngaphansi kwezinhlanganisela ezithile zezimo, ezingaboniswa ngumdwebo we-PT (Pressure-Temperature). Lo mdwebo ukhombisa ukuthi yimaphi amaminerali azinzile kumazinga athile okucindezela kanye nokushisa.
Isibonelo:
– I-Kyanite, i-andalusite, kanye ne-sillimanite ziyizinhlobo ezintathu ze-Al₂SiO₅ (ukwakheka okufanayo, isakhiwo esihlukile) ezizinzile ezimweni ezahlukene ze-PT.
– I-Andalusite ivame ukuqina uma icindezelekile kancane,
– I-Kyanite ekucindezelekeni okuphezulu,
– I-Sillimanite emazingeni okushisa aphezulu.
Ngakho-ke, ukuba khona kwenye yalezi zimbiwa emadwaleni ashintshashintshayo kungaba “i-thermometer yemvelo kanye ne-barometer” ukuchaza izimo zokwakheka kwedwala.
Umphumela wokushisa kanye nengcindezi ekwakhekeni kwamaminerali e-ore
Esimweni sezomnotho, izinga lokushisa kanye nokucindezela kunquma kakhulu indawo kanye nohlobo lwezinsalela zamaminerali ezibalulekile. Izinsalela zensimbi zingakheka ngezinqubo ze-magmatic, metamorphic, noma hydrothermal.
– Ezinhlelweni ze-magmatic, amaminerali e-ore afana ne-chromite noma i-magnetite angakhazimula futhi agxile emazingeni okushisa aphezulu.
– Ezinhlelweni zokushisa kwamanzi, amaminerali ensimbi avame ukwakheka ngoba uketshezi olushisayo oluthwala ama-ion ensimbi lubhekana nokushintsha kwezinga lokushisa/ingcindezi bese luwabangela.
– Ezinhlelweni ze-metamorphic, ingcindezi kanye nokushisa kungashukumisa izakhi ezithile futhi kwakhiwe ama-orogenic gold deposits, isibonelo ezindaweni zokushayisana kwamapuleti.
Izinguquko ezincane ekushiseni nasekucindezelekeni zingashintsha ukuncibilika kwamaminerali oketshezini, ngaleyo ndlela kunqunywe ukuthi amaminerali azofika nini nokuthi imithambo yamaminerali yakheka kuphi.
Izibonelo zangempela endaweni yemvelo
1. Amatshe entaba-mlilo kanye namatshe angenawo umoya: Izinga lokushisa lokupholisa le-magma likhiqiza amaminerali ahlukene ngokwendlela yokwakheka kwamakristalu. I-basaltic lava ephola ngokushesha yakha amakristalu amahle, kuyilapho i-granitic magma ephola kancane ingakhiqiza amakristalu amakhulu njenge-quartz kanye ne-feldspar.
2. Izindawo zokunciphisa: Ukucindezela okuphezulu kanye namazinga okushisa aphansi kakhulu kungakha amaminerali ahlukile njenge-glaucophane emadwaleni e-blueschist.
3. Izintaba ezibangelwa ukushayisana kwamapuleti: Ukucindezela okukhulu kanye namazinga okushisa aphezulu kukhiqiza amatshe aguqukile, anamaminerali athile abonisa ukujula kanye nokushisa kokwakheka kwawo.
Isiphetho
Izinga lokushisa kanye nokucindezela kuyizinto ezimbili eziyinhloko ezilawula ukwakheka kanye nokuguqulwa kwamaminerali eMhlabeni. Izinga lokushisa linquma amandla, amazinga okusabela, kanye nokulandelana kwekristalu, kuyilapho ingcindezi ilawula isakhiwo sekristalu, ubuningi, kanye nokuqina kwezigaba zamaminerali. Lezi zinto ezimbili zisebenza ndawonye ukudala izimo ze-PT ezihlukile, okuvumela amaminerali athile ukuthi akheke kuphela ezindaweni ezithile zejiyoloji. Ngokutadisha amaminerali akhona emadwaleni, singakwazi "ukufunda" irekhodi lezimo zokushisa kanye nokucindezela zesikhathi esidlule futhi siqonde izinqubo ezinkulu ezakha ungqimba loMhlaba kanye ne-mantle. Lokhu kuqonda kubalulekile futhi ekuhlolweni kwezinsiza zamaminerali, ukunciphisa izingozi zejiyoloji, kanye nocwaningo lokuvela kwamaplanethi.
Uma ufisa, ngingangeza izigatshana ezithile (isib. uBowen's Reaction Series, i-contact vs. i-regional metamorphism, noma i-PT diagrams) noma ngilungise lesi sihloko ukuze silungele imisebenzi yesikole/yasekolishi (kuphelele nezinkomba).
