He aha ngā toka pyroclastic, ā, me pēhea te hanga?
Ko ngā toka pyroclastic tētahi o ngā "rēkoata" mārama rawa atu o te kaha o te mahi a te puia. Ina pahū te puia, kāore e rere katoa ngā mea i panaia hei rangitoto. He maha ngā pahūtanga e ruaki ana i ngā kongakonga toka, pungarehu, me ngā kongakonga magma ka panaia ki te rangi, kātahi ka taka ki raro ka kohikohi. Kātahi ka taea e ēnei putunga te hanga toka pyroclastic. Hei mārama ki ngā toka pyroclastic, me tirotiro tātou i tō rātou whanaungatanga tata ki te momo pahūtanga, te rahi o te mea i panaia, te āhua o te kawe i aua mea, me te āhua o te "maukati" ki roto i te toka totoka.
Te whakamāramatanga o ngā toka pyroclastic
I te whakarapopototanga, ko ngā toka pyroclastic he toka i hangaia mai i ngā rauemi puia i tukuna i te wā o ngā pahūtanga pahū (bursting eruptions), ka tau, ka piri, ka whakapiri (lithification). Ko te kupu "pyroclastic" i ahu mai i te kupu Kariki: pyro (ahi) me te klastos (fragment). Nō reira, ka taea te whakamārama i te pyroclastic ko te "fragmentation i puta mai i te ahi/ngā mahi puia."
He rerekē ki ngā toka mura o waho pērā i te basalt, te andesite rānei, ka hangaia i te rere o te rangitoto, kātahi ka totoka, ka hangaia ngā toka pyroclastic mai i ngā kongakonga i puta mai i ngā pahūtanga—he kongakonga magma rānei e totoka ana i te rangi, he kongakonga toka tawhito rānei nō te tinana puia ka pakaruhia, ka maka atu.
Ngā rauemi hanga: mai i te pungarehu ki ngā poma puia
Ko ngā rauemi pyroclastic e kiia ana ko ngā pyroclasts. He rerekē te rahi o ngā pyroclasts, ā, mā te whakarōpūtanga rahi ka taea e ngā tohunga whenua te tautuhi i te momo putunga me te toka:
1. Pungarehu puia (pungarehu): rahi < 2 mm. Ka taea e te pungarehu te tino angiangi, ka tere te kawe e te hau, ā, ka taea te kapi i ngā wāhi whānui. Ina whakatakotoria matotoru, ka taea te hanga toka pēnei i te tuff. 2. Lapilli: rahi 2–64 mm. He rite te āhua ki te kirikiri, ka taea te waiho hei maramara toka, hei pata rānei o te magma e tere totoka ana. Ko ngā putunga e nui ana i te lapilli ka taea te hanga tuff lapilli, he toka pyroclastic waenga-kiko rānei.
3. Ngā poma me ngā poraka puia: rahi > 64 mm.– He kirihou tonu ngā poma puia ina whiua, nō reira ka taea te porowhita, te ātea rānei tōna āhua.
– Ko ngā poraka he kongakonga toka totoka kua whiua, he koki ake te āhua.
Ka taea e ēnei putunga taratara te hanga i ngā breccia pyroclastic.
Haunga te rahi, ka taea hoki te wehewehe i ngā pyroclasts mā ō rātou pūtake:
– Tamariki: he rauemi i ahu mai i te magma hou (hei tauira, te pumice, te scoria).
– Ritiki: ngā maramara toka tawhito mai i ngā pakitara o te rua, i ngā awaawa puia rānei.
– Ngā tioata: ngā kongakonga kohuke (hei tauira, te plagioclase, te pyroxene) e tukuna ana mai i te magma.
Me pēhea te hanganga o ngā toka pyroclastic?
He raupapa tukanga te hanganga o ngā toka pyroclastic: te pahūtanga → te kawe → te whakatakotoranga → te whakapūtanga. Ko ngā wāhanga e whai ake nei.
1) Ngā mea e whakaoho ana i ngā pahūtanga pahū: te pēhanga hau me te matotoru o te magma
Ko ngā pahūtanga pahūtanga ka puta i te nuinga o te wā ina nui te hau (kohu wai, CO₂, SO₂) i roto i te magma, ā, he matotoru hoki, kia taea ai e te hau te puta mārire. Nō reira, ka nui haere te pēhanga, ka puta he pahūtanga. Ka pakaru te magma hei kongakonga ririki i te mea ka horapa ohorere te hau—he rite ki te rūrū i tētahi kēne houra tunutunu, kātahi ka whakatuwherahia, engari i runga i te tauine nui me te pāmahana tino teitei.
Ka puta mai i tēnei wāhanga ngā rauemi pēnei i te pungarehu puia, te rāpiti, te pungapunga, te kōhatu, ngā poma, me ngā poraka. Koinei ngā rauemi matua mō ngā toka pyroclastic.
2) Te peinga me te kawe: ka taka hei pungarehu, ka paheke rānei hei rerenga ahi mura.
Kia oti te hanga, ka neke ngā pyroclasts i roto i ētahi huarahi:
– Te hinganga o te pyroclastic
Ka makahia ngā rauemi ki te āhuarangi, kātahi ka taka iho nā te kaha o te kaha ā-papa. Ka taea e ngā hau te kawe i te pungarehu pai mō ngā rau kiromita, ko ngā lapilli me ngā poma ka taka tata atu ki te pokapū o te pahūtanga. Ko ngā putunga pakaru ka tino pai te paparanga, ka kapi i te mata.
– Ngā iahiko matotoru o te pyroclastic
He ranunga wera rawa ēnei o te hau, te pungarehu, me ngā maramara toka e rere tere ana i raro i ngā pari - he tere rawa, ā, he kaha whakamate. He nui ake ngā putunga (kāore i te tino paparangahia i ngā wā katoa), ka taea te kapi i ngā awaawa me ngā mania, ā, he maha ngā wā ka puta he putunga nui.
– Te ngaru nui o te ahi
Ka taea e ngā ngaru pyroclastic waimeha, pōrearea hoki te wikitoria i ngā arai whenua. He maha ngā wā ka whakaatuhia e ō rātou putunga he hanganga parataiao pērā i te whakawhiti-whakakikorua.
Ka pā tēnei momo kawe i te kakano whakamutunga o te toka: ahakoa he paparanga angiangi, he rahi, he whakarōpūtia, he ranunga rahi "matapōkere" rānei.
3) Whakapūpūnga: ka kohia hei paparanga matotoru
I roto i te wā, ka kohikohi ngā pyroclasts hei putunga. Ka taea e ngā putunga te maha henimita ki te tekau mita te matotoru, i runga i te rahi me te wāhi o te pahūtanga. Ka taea e ngā putunga te whakakī i ngā awa, te aukati i ngā awa, te hanga mania hou rānei. I tēnei wāhanga, he āhua wetewete tonu te rauemi (he rite ki te onepu, te kirikiri, te pungarehu rānei).
4) Te whakapūmautanga: mai i te paru wetekina ki te toka totoka
Hei huri hei toka, me whakatōkia ngā putunga pyroclastic mā roto i:
– Te whakakīkī: ka pēhia te paru e te kawenga mai i te paparanga i runga ake nei kia iti ai ngā pūwero.
– Te whakapūmau: ko ngā kohuke e pupū ake ana i te wai (hei tauira, te silica, te calcite, te zeolite, te uku) ka "piri" i ngā pata.
– Te whakarewa i runga i ētahi putunga wera: Mēnā ka taka, ka rere rānei te putunga i te mea e tino wera tonu ana, ka piri tahi ngā kongakonga karāhe puia, ka hanumi ngātahi. Ka puta he putunga whakarewa mārō ake, he putunga kiato ake (ignimbrite).
Ka tere pea te tukanga whakapūtātanga i runga i te tauine whenua, ina koa he matotoru, he wera, ā, he tere te tanumia o ngā putunga.
Ngā momo toka pyroclastic noa
Anei ētahi momo e kitea pinepinetia ana:
1. Tūf
He toka pyroclastic he mea hanga te nuinga ki te pungarehu puia. Ka taea e te tuff te ahua pai ki te ahua matotoru, i runga i te rahi o te ranunga. He whānuitia te whakamahinga o te tuff hei rauemi hanga whare i roto i ngā wāhi maha, ahakoa he rerekē tōna kaha.
2. Whakakā (whakakā)
I ahu mai i ngā putunga rere o te mura ahi wera rawa, he nui te pungarehu, he maha ngā wā he kakano whakapiri, ka taea e ngā ignimbrite te hanga mania whānui, hei tohu hoki mō ngā pahūtanga nui.
3. Ngā breccia pyroclastic
He mea tito mai i ngā kongakonga koki nunui (poraka) he ranunga rānei o ngā kongakonga nunui i roto i te anga pungarehu/rapili. He tohu tēnei mō te pahūtanga, te hinganga rānei e puta ai ngā kongakonga nunui.
4. Te tāpa o te rāpiti
He kirikiri momona i te lapilli (he kirikiri 2–64 mm te roa). He āhua "pōturi" te kakano nā te mea he nui ake ngā kongakonga kua mau ki roto i te anga pungarehu.
He aha te hiranga o te ako i ngā toka pyroclastic?
He mea nui ngā toka pyroclastic nā te mea:
– Hei tuhi i te hītori o ngā pahūtanga: mai i te rahi o ngā maramara, te hanganga, me te hanganga o ngā paparanga, ka taea e ngā tohunga whenua te whakamārama i te momo pahūtanga me tōna kaha.
– Te āwhina i te mahere mō ngā tūponotanga o te puia: ko ngā putunga rere o te mura ahi me te hinganga o te pungarehu e tohu ana i ngā wāhi kua pāngia, ā, tera pea ka pāngia anō.
– He rauemi whai hua: ka huri ētahi putunga mura ahi hei puna wai, hei kohuke, hei toka ahumahi rānei; engari ka pakarukaru hoki, ka ngāwari hoki ki te horo whenua ina pāngia e te huarere.
Te Katinga
Ko ngā toka pyroclastic he toka i hangaia mai i ngā kongakonga o ngā rauemi puia i puta mai i ngā pahūtanga pahū. Ko ēnei rauemi—mai i te pungarehu me te lapilli ki ngā poma me ngā poraka—ka haria e te pungarehu, e ngā rerenga pyroclastic rānei, kātahi ka tau, ka whakakīkī, ka whakapiri, ā, i ētahi wā ka whakarewahia nā te wera, ā, ka mutu ka hanga he toka totoka pērā i te tuff, te ignimbrite, me te pyroclastic breccia. Mā te ako i ngā toka pyroclastic, ehara i te mea ka mārama noa tātou ki ngā tukanga whenua e hanga ana i te mata o te Ao, engari ka taea hoki te whai i ngā tohu o ngā pahūtanga o mua hei matapae i ngā mōrearea ā muri ake nei.
Ki te hiahia koe, ka taea e au te whakarerekē i tēnei tuhinga mō ngā hiahia kura (māmā ake), whare wānanga (hangarau ake), tāpiri atu rānei i ngā tauira o ngā toka pyroclastic i kitea i Indonesia me ō rātou wāhi me ō rātou āhuatanga.
