Ayini Amadwala E-Pyroclastic Futhi Akhiwa Kanjani?
Amatshe e-pyroclastic angenye "yamarekhodi" acacile kakhulu okuqina komsebenzi wentaba-mlilo. Lapho kuqhuma intaba-mlilo, akuzona zonke izinto ezikhishwe zigeleza njenge-lava. Ukuqhuma okuningi empeleni kukhipha izingcezu zamatshe, umlotha, kanye nezingcezu ze-magma ezikhishwa emoyeni, bese ziwela phansi futhi ziqongelele. Lawa matshe angabe esebumba amatshe e-pyroclastic. Ukuze siqonde amatshe e-pyroclastic, sidinga ukuhlola ubuhlobo bawo obuseduze nohlobo lokuqhuma, ubukhulu bezinto ezikhishwe, ukuthi lezo zinto zithuthwa kanjani, nokuthi ekugcineni "zivalelwe" kanjani edwaleni eliqinile.
Incazelo yamadwala e-pyroclastic
Kalula nje, amatshe e-pyroclastic angamatshe akhiwe ngezinto zentaba-mlilo ezikhishwa ngesikhathi sokuqhuma okuqhumayo (ukuqhuma okuqhumayo), bese zihlala phansi bese ziqiniswa futhi ziqiniswe (lithification). Igama elithi "pyroclastic" livela kwelesiGriki: pyro (umlilo) kanye ne-klastos (ucezu). Ngakho-ke, i-pyroclastic ingachazwa ngokuthi "ukuqhekeka okubangelwa umsebenzi womlilo/wentaba-mlilo."
Ngokungafani namadwala acwebezelayo aphumayo njenge-basalt noma i-andesite, akhiwa lapho i-lava igeleza bese iqina, amadwala e-pyroclastic akhiwa ngezingcezu ezibangelwa ukuqhuma—kungaba izingcezu ze-magma eziqina emoyeni, noma izingcezu zamadwala amadala avela emzimbeni wentaba-mlilo aqhekeziwe futhi alahlwe.
Izinto zokwakha: kusukela kumlotha kuya kumabhomu entaba-mlilo
Izinto ezibizwa ngokuthi ama-pyroclast zibizwa ngokuthi ama-pyroclast. Ama-pyroclast ayahlukahluka kakhulu ngobukhulu, futhi ukuhlukaniswa kosayizi kusiza izazi ze-geology ukuhlonza uhlobo lwe-deposit kanye nedwala:
1. Umlotha wentaba-mlilo (umlotha): usayizi < 2 mm. Umlotha ungaba mncane kakhulu, uthwalwe kalula ngumoya, futhi ungamboza izindawo ezinkulu. Uma ubekwe ujiyile futhi uhlanganiswe, ungakha amatshe anjenge-tuff. 2. I-Lapilli: usayizi 2–64 mm. Uma umile njengetshe eliyingcosana, ungaba yizingcezu zamatshe noma amaconsi e-magma aqina ngokushesha. Ama-deposit aphethwe yi-lapilli angakha i-lapilli tuff noma idwala eliphakathi nendawo eliyi-pyroclastic.
3. Amabhomu entaba-mlilo namabhulokhi: usayizi > 64 mm.– Amabhomu entaba-mlilo ngokuvamile ahlala epulasitiki uma ephonswa, ngakho-ke isimo sawo singaba yindilinga noma sibe yi-aerodynamic.
– Amabhulokhi ngokuvamile ayizingcezu zamatshe aqinile eziphonswe, isimo sawo sigobile kakhulu.
Ama-coarse deposits afana nalawa angakha ama-pyroclastic breccias.
Ngaphandle kobukhulu, ama-pyroclast angahlukaniswa ngemvelaphi yawo:
– Ubusha: izinto ezivela ku-magma entsha (isb. i-pumice, i-scoria).
– I-Lithic: izingcezu zamatshe amadala avela ezindongeni ze-crater noma emiseleni yezintaba-mlilo.
– Amakristalu: izingcezu zamaminerali (isib. i-plagioclase, i-pyroxene) ezikhishwa ku-magma.
Amatshe e-pyroclastic akhiwa kanjani?
Ukwakheka kwamadwala e-pyroclastic kuwuchungechunge lwezinqubo: ukuqhuma → ukuthutha → ukufakwa kwe-lithification. Izigaba zimi kanje.
1) Izinto ezibangela ukuqhuma okuqhumayo: umfutho wegesi kanye nokuxinana kwe-magma
Ukuqhuma okuqhumayo kuvame ukwenzeka lapho i-magma igcwele igesi (umhwamuko wamanzi, i-CO₂, i-SO₂) kanye/noma iqine ngokwanele ukuvumela igesi ukuthi iphume kancane. Ngenxa yalokho, ingcindezi iyakhula, okuholela ekuqhumeni. I-magma iyaqhekeka ibe yizingcezu ezincane njengoba igesi ikhula ngokuzumayo—njengokushukumisa ithini lesoda bese ulivula, kodwa ngezinga elikhulu futhi emazingeni okushisa aphezulu kakhulu.
Lesi sigaba sikhiqiza izinto ezifana nomlotha wentaba-mlilo, i-lapilli, i-pumice, i-scoria, amabhomu, kanye namabhulokhi. Lezi yizinto eziyinhloko zokusetshenziswa kwamatshe e-pyroclastic.
2) Ukukhipha kanye nokuthuthwa: kuwa njengomlotha noma amaslayidi njengoba kugeleza i-pyroclastic.
Uma sekwakhiwe, ama-pyroclast ahamba ngezindlela eziningana:
- Ukuwa kwe-pyroplastic
Izinto zikhishwa emoyeni bese ziwela ngenxa yamandla adonsela phansi. Umlotha omncane ungathwalwa yimimoya amakhulu amakhilomitha, kuyilapho ama-lapilli namabhomu ewela eduze nesikhungo sokuqhuma. Ama-fallout deposits ngokuvamile abekwa kahle futhi amboze indawo engaphezulu.
– Imisinga yobuningi be-pyroclastic
Lezi yizingxube ezishisayo kakhulu zegesi, umlotha, kanye nezingcezu zamadwala ezigeleza ngokushesha phansi emithambekeni—ngesivinini esikhulu futhi zinamandla okubulala. Amadiphozithi avame ukuba makhulu kakhulu (awahlali ebekwe kahle njalo), angamboza izigodi namathafa, futhi avame ukukhiqiza amadiphozithi amakhulu.
- Ukwanda kwe-pyroplastic
Amagagasi e-pyroclastic ancibilikayo futhi aguquguqukayo anganqoba izithiyo zesimo sendawo. Ama-deposit awo avame ukubonisa izakhiwo ze-sedimentary ezifana ne-cross-lamination.
Le ndlela yokuhamba ithonya ukuthungwa kwedwala lokugcina: kungakhathaliseki ukuthi lihlelwe kahle, likhulu, lihlelwe ngezigaba, noma lixube "ngokungahleliwe" ngobukhulu.
3) Ukuthuthwa kwendle: kuqongelela ezingqimbeni ezijiyile
Ngokuhamba kwesikhathi, ama-pyroclast aqoqana abe yizicucu. Izicucu zingaba ngamasentimitha ambalwa kuya kwamashumi amamitha ubukhulu, kuye ngobukhulu bendawo yokuqhuma nendawo. Izicucu zingagcwalisa izitsha, zivale imifula, noma zakhe amathafa amasha. Phakathi nalesi sigaba, izinto zisalokhu zikhululekile (ezifana nesihlabathi, amatshe ayigugu, noma umlotha).
4) Ukuguqulwa kwe-lith: kusukela enhlabathini ekhululekile kuya edwaleni eliqinile
Ukuze ibe yidwala, ama-pyroclastic deposits kumele adlule ku-lithification ngokusebenzisa:
– Ukuminyana: umthwalo ovela ongqimbeni olungenhla ucindezela inhlabathi ukuze ama-pores anciphe.
– Ukufaka usimende: amaminerali aphuma emanzini (isib. i-silica, i-calcite, i-zeolite, ubumba) “anamathisela” okusanhlamvu ndawonye.
– Ukushisela ezindaweni ezithile ezishisayo: Uma idiphozithi iwela noma igeleza isashisa kakhulu, izingcezu zengilazi yentaba-mlilo zinganamathelana futhi zihlangane. Lokhu kukhiqiza i-tuff eshisiwe eqinile futhi enciphile (i-ignimbrite).
Inqubo yokuguqulwa kwe-lithification ingenzeka ngokushesha ngokwezinga le-geological, ikakhulukazi uma ama-deposits ejiyile, eshisa, futhi agqitshwe ngokushesha.
Izinhlobo ezivamile zamadwala e-pyroclastic
Nazi ezinye izinhlobo ezivame ukutholakala:
1. I-Tuff
Idwala eliyi-pyroclastic elakhiwe kakhulu ngomlotha wentaba-mlilo. I-Tuff ingaba yincane noma ibe mancane, kuye ngobukhulu bengxube. I-Tuff isetshenziswa kabanzi njengezinto zokwakha ezindaweni eziningana, yize amandla ayo ehlukahluka.
2. I-Ignimbrite (i-ignimbrite)
Ngokuvamile etholakala ezitsheni zokugeleza kwe-pyroclastic ezigcwele umlotha, ezishisa kakhulu, ngokuvamile ezinesimo esihlanganisiwe, ama-ignimbrites angakha amathafa amakhulu futhi asebenze njengezimpawu zokuqhuma okukhulu.
3. I-pyroclastic breccia
Yakhiwe ngezingcezu ezinkulu ze-angular (amabhlogo) noma ingxube yezingcezu ezinkulu ku-ash/lapilli matrix. Kubonisa ukuqhuma noma ukudilika okukhiqiza izingcezu ezinkulu.
4. I-Lapilli tuff
I-tuff ecebile nge-lapilli (okusanhlamvu okungu-2–64 mm). Ukuthungwa kubonakala “kunamabala” ngoba izingcezu ezinkulu zifakwe ku-ash matrix.
Kungani kubalulekile ukufunda amatshe e-pyroclastic?
Amatshe e-pyroclastic abalulekile ngoba:
– Ukurekhoda umlando wokuqhuma: kusukela ngobukhulu bezingcezu, ukwakheka, kanye nesakhiwo sezingqimba, izazi ze-geology zingachaza uhlobo lokuqhuma kanye nobukhulu balo.
– Ukusiza ekudwebeni imephu yezingozi zentaba-mlilo: amadiphozithi okugeleza kwe-pyroclastic kanye nokuwa komlotha kubonisa izindawo ezithintekile futhi ezingase zithinteke futhi.
– Iwusizo njengomthombo: ezinye izinsalela ze-pyroclastic ziba yimithombo yamanzi, amaminerali, noma amatshe ezimboni; kodwa futhi zingaba buthakathaka futhi zithambekele ekuqhekekeni komhlabathi lapho zigugile.
I-Penutup
Amatshe e-pyroclastic angamatshe akhiwe ngezingcezu zezinto zentaba-mlilo ezibangelwa ukuqhuma okuqhumayo. Lezi zinto—ezisukela kumlotha kanye ne-lapilli kuya kumabhomu kanye namabhulokhi—zithuthwa ngokuwa komlotha noma ukugeleza kwe-pyroclastic, bese zihlala phansi, ziqine, zisimende, futhi ngezinye izikhathi zishiselwe ngenxa yokushisa, ekugcineni zakhe amatshe aqinile njenge-tuff, i-ignimbrite, kanye ne-pyroclastic breccia. Ngokutadisha amatshe e-pyroclastic, asigcini nje ngokuqonda izinqubo ze-geological ezakha ubuso boMhlaba kodwa futhi singalandelela iminonjana yokuqhuma kwangaphambilini ukuze sibikezele izingozi zesikhathi esizayo.
Uma ufisa, ngingayivumelanisa le ndatshana nezidingo zesikole (ezilula), zasekolishi (ezobuchwepheshe kakhulu), noma ngengeze izibonelo zamatshe e-pyroclastic atholakala e-Indonesia kanye nezindawo zawo kanye nezici zawo.
