Me pēhea te tātari i ngā tauira toka puia
He taahiraa nui te tātari i ngā tauira toka puia ki te mārama ki te hītori o ngā pahūtanga, te taiao hanganga, te hanganga o te magma, me ngā rauemi me ngā tūponotanga whenua pea i roto i tētahi rohe. Kei roto i ngā toka puia he "rēkoata" o ngā tukanga e puta ana i raro i te mata o te Ao—mai i te whakatiotanga kohuke me te whakapakeketanga tere ki ngā taunekeneke ki te wai, ki te hau rānei. E matapakihia ana e tēnei tuhinga te tātari pūnaha i ngā tauira toka puia, mai i te wāhanga tauira parae ki te whakamārama i ngā hua taiwhanga.
1. Te whakarite me te tauira i te mara
Ka tīmata te tātari pai ki te tauira tika. I te mara, whakatauhia te kaupapa o te tātari: ahakoa mō te tautuhi momo toka, te tātari petrographic, te matū whenua, te whakatau i te pakeketanga, ngā rangahau whakarerekētanga hydrothermal rānei. Mā tēnei kaupapa ka whakatauhia te maha o ngā tauira, tōna rahi, me ngā wāhi tātari.
I te wā e kohi ana i te kōhatu, tīpakohia ngā kōhatu hou kāore i te tino tawhito, kāore he maha o ngā kapiti kī tonu i ngā kohuke tuarua, ā, kāore anō hoki i poke i te oneone. Āta karohia ngā mata kua tino waikura, kua kapi rānei i te pūkohu. Mena ko ngā mea kua tawhito anake e wātea ana, wahia te kōhatu kia kitea ai te roto hou ake.
Tuhia ngā raraunga ā-marae taipitopito: ngā taunga GPS, te teitei, ngā waeine whenua, ngā whanaungatanga paparanga whenua (hei tauira, ko tēhea paparanga kei runga ake/kei raro iho i te tauira), ngā hanganga puia (ngā rerenga rangitoto, ngā putunga wai, ngā toka pūngāwerewere), te rahi o te kōpura, te kaha o ngā pūngāwerewere, me te whakatakotoranga hanganga (hei tauira, te takotoranga toka pūngāwerewere). Tangohia ngā whakaahua horopaki o te papa whenua me ngā whakaahua tata o ngā tauira i mua i te kohikohinga. Tāutuhia ngā tauira kia rite ki te tikanga, whakatakotoria ki roto i ngā putea tauira, ka tapaina ki ngā tapanga ārai wai.
2. Whakaahuatanga nui (tauira ringaringa)
Kia kohia ngā tauira, mahia he whakaahuatanga makroskopi—he tātaritanga tirohanga me te kore he karu hiko. Mā tēnei wāhanga ka whakaratohia he tirohanga tuatahi ki te whakarōpūtanga o te toka.
Ētahi mea hei tirotiro:
– Tae: ko te nuinga he papara pouri, he andesite hina, he rhyolite māmā ake, engari ka pāngia te tae e te waikura me te whakarerekētanga.
– Kakano: āpanitika (kāore he tioata e kitea ana), pōpiritika (he phenocrysts nui kei roto i te papa whenua angiangi), he vesicular (he kōhao), he karāhe (he karāhe puia), he pyroclastic rānei.
– Hanganga: here rere, amygdaloidal (ngā pūwero kī tonu i te kohuke), breccia, paparanga tuff.
– Te pakeketanga me te tauhohenga: ngā whakamātautau māmā pēnei i te pakeketanga whanaunga, te aukumetanga (te noho mai o te aukumeiti), me te tauhohenga HCl hei kimi i ngā warowaihā tuarua.
Mai i konei, ka taea e koe te whakatakoto i ngā whakapae tuatahi: hei tauira "te andesite porphyritic me ngā phenocrysts plagioclase me te pyroxene" te "lapilli tuff me ngā kongakonga lithic".
3. Te whakarite tauira mō te tātari taiwhanga
He rerekē ngā whakaritenga e hiahiatia ana mō ngā tātaritanga rerekē:
– Ngā wāhanga angiangi mō te petrography moroiti.
– Paura toka mō te XRF, ICP-OES/ICP-MS, XRD rānei.
– Kua wehea ngā kongakonga kohuke (wehenga kohuke) hei whakatau i te pakeketanga (hei tauira, Ar-Ar i roto i te feldspar, U-Pb rānei i roto i te zircon).
Me whakarite kia ma ngā taputapu kuru me te mira kia kore ai e horapa te poke i waenga i ngā tauira. Ko te mea pai, whakamahia he tikanga "horoi parakore", he huri rānei i te quartz ma i waenga i ngā tauira.
4. Tātaritanga petrographic me te karuārai polarizing
Ko te petrography te kaupapa matua o te tātari toka. Mā ngā wāhanga angiangi, ka taea e koe te tautuhi i ngā kohuke, ō rātou ōrau whanaunga, ngā kakano tioata, me ngā tukanga hanganga muri.
Ngā mea hei mōhio:
1. Te tautuhi i ngā kohuke matua: te plagioclase, te pyroxene (augite), te olivine, te hornblende, te biotite, te quartz, te K-feldspar.
2. Ngā kohuke tāpiri: magnetite, ilmenite, apatite, zircon.
3. Kakano:
– Pōpiritiki: e whakaatu ana i ngā wāhanga e rua o te whakamatao (he puhoi i te hohonutanga, he tere i te mata).
– Intersertal/intergranular: he mea noa i roto i te karāhe.
– Pilotaxitic: ngā microlite plagioclase kua whakaritea matapōkeretia/kua tohua.
– Glomeroporphyritic: he phenocrysts kei roto i ngā rōpū.
4. Huringa: hei tauira, ka huri te olivine hei iddingsite, ka huri te plagioclase sericitated, ka whakakōroritia ngā kohuke mafic.
Mai i te petrography, ka taea e koe te hono i ngā toka ki tētahi raupapa magma motuhake (hei tauira, te basaltic, te andesitic, ki te rhyolitic) me te whakatau tata i te hītori whakamatao.
5. Tātaritanga matū whenua: te hanganga o ngā huānga matua me ngā huānga iti
Mā te matū whenua ka whakaratohia he raraunga tauanga mō te hanganga o te toka. E rua ngā rōpū tātaritanga e whakamahia whānuitia ana:
– Ngā huānga matua: SiO₂, Al₂O₃, FeO/Fe₂O₃, MgO, CaO, Na₂O, K₂O, TiO₂, P₂O₅. I te nuinga o te wā ka inehia mā te XRF.
– Ngā huānga iti me te REE: pērā i te Rb, Sr, Ba, Nb, Ta, Zr, Y, La–Lu. He maha ngā wā ka inehia mā te ICP-MS.
Ko te tikanga, ka whakamahia he hoahoa paerewa hei whakamārama:
– TAS (Karaiha-Hilika Katoa) mō te whakarōpūtanga o te basalt–andesite–dacite–rhyolite.
– Ngā hoahoa Harker hei tiro i ngā au o te rerekētanga o te magma (hei tauira, te hekenga o te MgO i te pikinga o te SiO₂).
– Te hoahoa pūngāwerewere (maha-huānga) me te tauira REE hei whakamārama i te pūtake magma, te awe o te ruku, te poke rānei o te kiripaka.
Tauira whakamārama: he maha ngā wā e hono ana ngā toka he nui te whakanikoniko o LILE (Rb, Ba, K) me ngā āhua rerekē o Nb-Ta ki ngā magma pewa tōpana.
6. XRD mō te tautuhi i ngā kohuke pai me te whakarerekētanga
Mena he nui ngā rauemi angiangi kei roto i te toka (te uku angiangi, te uku whakarerekētanga), he whai hua te X-ray diffraction (XRD) mō te tautuhi i ngā kohuke uaua ki te wehewehe i roto i ngā wāhanga angiangi, pērā i te kaolinite, te smectite, te illite, te zeolite, te silica amorphous rānei.
He pai hoki te XRD mō te aromatawai i te nui o te whakarerekētanga hydrothermal i roto i ngā toka puia, hei tauira, te propylitic (chlorite-epidote), te argillic (kaolinite-illite), ngā rohe silicified rānei.
7. Tātaritanga kakano me te āhua me te SEM-EDS
Mā te Matawai Irahiko Matawai (SEM) ka taea te whakarato i ngā whakaahua kounga teitei o ngā mata karaihe kohuke me ngā mata karāhe puia. Mā te whakamahi tahi me te Matawai Whakamarara Pūngao (EDS), ka taea te whakatau i te hanganga matū o ngā pūwāhi motuhake, pēnei i:
– te hanganga karāhe puia,
– te whakarōpūtanga i roto i te plagioclase,
– te hanganga kohuke mātotoru (magnetite-ilmenite),
– ngā hua whakarerekētanga i roto i ngā pūwero.
E whakamahia ana te SEM-EDS hei mārama ki ngā tukanga tere pēnei i te whakamatao ohorere, te wehewehenga pyroclastic, me te tioata microlite.
8. Te whakatau i te pakeketanga (geochronology) mēnā e tika ana
Hei whakautu i te pātai "nōnahea i hangaia ai tēnei toka?", ka whakamahia te matawhenua. Ka whiriwhiria te tikanga i runga i te momo kohuke me te tau e whakatauhia ana:
– K-Ar, Ar-Ar rānei: he mea noa mō ngā toka puia miriona tau te pakeke me ngā kohuke whai K (feldspar, biotite) me te papa whenua rānei.
– U-Pb i roto i te zircon: he tino kaha mō ngā toka hiraka (dacite-rhyolite) kei roto ko te zircon.
– Ka whakamahia te (U-Th)/He, ētahi atu tikanga rānei mō ngā tono motuhake i ētahi wā.
Me tino whakahaere te matawhenua i ngā whakarerekētanga nā te mea ka taea e ngā huringa kohuke te whakararuraru i te pūnaha isotopic.
9. Te whakaurunga me te whakamaoritanga raraunga
Ko te taahiraa tino nui ko te whakakotahi i ngā hua katoa:
– Mā te whakaahuatanga o te mara ka whakamāramahia te horopaki (te rangitoto, te pūngao, te pungao, te taiao).
– Ka whakamārama te petrography i te ako i ngā kohuke me te kakano o te whakatōtika.
– Ka whakamārama te matū whenua i te whakarōpūtanga me te whanaketanga o te magma.
– Mā te XRD/SEM ka whakamārama ngā kohuke moroiti me ngā whakarerekētanga.
– Mā te matawhenua e whakaatu he anga wā.
Mai i tēnei whakaurunga, ka taea e koe te hanga i ngā whakamāramatanga: te momo toka, te raupapa magma (tholeiitic/calc-alkaline), ngā tukanga rerekētanga (te wehewehenga tioata, te whakaranu magma), ngā taunekeneke ki te kirinuku, me ngā whanaungatanga ki ngā tectonics ā-rohe.
10. Ngā hapa noa me ngā tohutohu whai hua
Ko ētahi hapa noa:
– te tango tauira kua tino tawhito rawa, ā, ka "paru" te matū whenua i te whakarerekētanga,
– kāore i te tuhi tika i te tauwāhi me te horopaki paparanga whenua,
– te whakawhiti-para i te wā e huri ana,
– te whakawhirinaki ki tētahi tikanga kotahi, kāore he manatoko whakawhiti.
Ngā tohutohu whai hua:
– tangohia he tauira tārua,
– tiakina te wāhanga "tiwhikete" hei tohutoro,
– tuhia ngā mahi whakarite katoa,
– te whakamahi i ngā paerewa me ngā wāhi takoto kau mō te tātaritanga matū whenua.
Te Katinga
Ehara i te mea ko te mōhio noa ki ō rātou ingoa te tikanga o te tātari i ngā tauira toka puia; engari me mārama hoki ki ngā tukanga i hanga ai. Mā te huarahi taahiraa-i-te-taahiraa—mai i te mātakitaki i te mara, te whakaahuatanga makaro, te petrography, te geochemistry, ki ngā tātari matatau pēnei i te XRD, SEM-EDS, me te geochronology—ka taea e koe te hanga i tētahi pikitia katoa o te whanaketanga magma me te hītori puia o tētahi rohe. Me hangai tonu te tikanga i whiriwhiria ki te pātai rangahau, kia pai ai te tātari, kia tika ai, kia whai tikanga ai hoki.
Ki te hiahia koe, ka taea e au te whakarite i tēnei tuhinga kia arotahi ake ki ngā hiahia motuhake (hei tauira, mō ngā mahi o te kāreti, ngā aratohu taiwhanga, ngā rangahau mara rānei mō tētahi puia motuhake), tae atu ki te tāpiri i tētahi rārangi pukapuka me te whakatakotoranga pūtaiao.
