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I-Geology yePumice yase-Indonesia

I-pumice noma i-pumice wuhlobo lwetshe elilula ngombala, liqukethe igwebu elenziwe ngamabhamuza anezindonga zengilazi, futhi ngokuvamile libizwa ngokuthi ingilazi yentaba-mlilo eyisilicate.

Lawa matshe akhiwa yi-acidic magma ngesenzo sokuqhuma kwentaba-mlilo okukhiphela izinto emoyeni; bese uthuthwa ovundlile bese unqwabelana njengetshe le-pyroclastic.

I-Pumice inezakhiwo eziphakeme ezihlukene, iqukethe inani elikhulu lamaseli (isakhiwo seselula) ngenxa yokwanda kwegwebu legesi yemvelo eliqukethwe lapho, futhi ngokuvamile litholakala njengento ekhululekile noma izingcezu ku-volcanic breccia. Ngenkathi amaminerali aqukethwe ku-pumice yi-feldspar, i-quartz, i-obsidian, i-cristobalite, ne-tridymite.

I-Pumice yenzeka lapho i-acidic magma ikhuphukela phezulu futhi kungazelelwe ihlangana nomoya wangaphandle. Igwebu lengilazi lemvelo eline/igesi equkethwe kuyo linethuba lokuphunyuka futhi i-magma iba yiqhwa kungazelelwe, i-pumice ngokuvamile iba khona njengezicucu ezikhishwa ngesikhathi sokuqhuma kwentaba-mlilo ezinobukhulu obusuka kubhuqu ukuya emadwaleni.

I-Pumice ivamise ukuvela njengokuncibilika noma ukugeleza, izinto ezixegayo noma izingcezwana ezikhungweni zentaba-mlilo.

I-Pumice ingenziwa futhi ngokushisa i-obsidian, ukuze igesi ibaleke. Ukushisisa okwenziwe ku-obsidian kusuka e-Krakatoa, izinga lokushisa elidingekayo ukuze kuguqulwe i-obsidian ibe yi-pumice ephakathi kuka-880oC. Amandla adonsela phansi athile e-obsidian ekuqaleni okwakuyi-2.36 yehla yaya ku-0.416 ngemva kokwelashwa, ngakho-ke iyantanta emanzini. Leli tshe le-pumice linezindawo zokudonsa amanzi.

I-Pumice iwumbala omhlophe kuya kokumpunga, okuphuzi ukuya kokubomvu, ukuthungwa kwe-vesicular enosayizi we-orifice, ohlukayo ngokuhlobene nomunye nomunye noma hhayi ngesakhiwo esishile esinama-orifice aqondile.

Kwesinye isikhathi imbobo igcwala i-zeolite/calcite. Leli tshe alikwazi ukumelana namazolo aqandayo (isithwathwa), hhayi ama-hygroscopic (amanzi amuncayo). Inezici zokudlulisa ukushisa okuphansi. Amandla okucindezela aphakathi kuka-30 – 20 kg/cm2. Ukwakheka okuyinhloko kwamaminerali e-amorphous silicate.

Ngokusekelwe endleleni yokwakheka (i-deposition), ukusatshalaliswa kosayizi wezinhlayiyana (ucezu) kanye nezinto ezivela kuyo, amadiphozithi e-pumice ahlukaniswa ngale ndlela elandelayo:

Indawo engaphansi
I-Sub-aqueous

I-ardante entsha; okungukuthi amadiphozithi akhiwe ukuphuma okuvundlile kwamagesi ku-lava, okuholela engxubeni yezingcezu ezinosayizi abahlukahlukene kufomu le-matrix.
Umphumela wediphozithi kabusha (redeposit)

Kusukela ku-metamorphosis, izindawo ezicishe zibe yintaba-mlilo kuphela ezizoba namadiphozithi e-pumice yokonga. Inkathi yokuma kwezwe yalawa madiphozithi iphakathi Kwemfundo Ephakeme kanye neyamanje. Izintaba-mlilo ezazikhona phakathi nale nkathi yokuma kwezwe zazihlanganisa unqenqema loLwandlekazi iPacific kanye nendlela esuka oLwandle iMedithera iya e-Himalaya bese iya eMpumalanga ye-India.

Amatshe afana namanye ama-pumice ayi-pumicite kanye ne-volcanic cinder. I-Pumicite inokwakheka kwamakhemikhali okufanayo, imvelaphi yokwakheka kanye nesakhiwo sengilazi njenge-pumice. Umehluko ukusayizi wezinhlayiyana kuphela, ongaphansi kwama-intshi angu-16 ububanzi. I-Pumice itholakala ngokuqhathaniswa nendawo eyavela kuyo, kuyilapho i-pumicite ihanjiswe umoya ibanga elide, futhi yafakwa ngendlela yokunqwabelana komlotha osayizi ocolekile noma njenge-tuff sediment.

I-volcanic cinder inezicucu ezibomvu ze-vesicular, ezafakwa ngesikhathi sokuqhuma kwedwala le-basaltic ngenxa yokuqhuma kwentaba-mlilo. Iningi lamadiphozithi e-cinder atholakala njengezingcezu zokulala ezi-conical ezisukela ku-intshi engu-1 ukuya kuma-intshi amaningana ububanzi.

Amathuba ePumice yase-Indonesia

E-Indonesia, ubukhona be-pumice buhlala buhlotshaniswa nochungechunge lwezintaba-mlilo ze-Quaternary to Tertiary. Ukusatshalaliswa kwayo kuhlanganisa izindawo zaseSerang naseSukabumi (West Java), isiqhingi saseLombok (NTB) kanye nesiqhingi saseTernate (Maluku).

Amathuba okufakwa kwe-pumice anokubaluleka kwezomnotho neziqiwu ezinkulu kakhulu asesiqhingini saseLombok, eNtshonalanga yeNusa Tenggara, esiqhingini saseTernate, eMaluku. Inani lezinqolobane ezikaliwe endaweni lilinganiselwa ngaphezu kwamathani ayizigidi eziyi-10. Endaweni yaseLombok, ukuxhashazwa kwe-pumice sekwenziwe kusukela eminyakeni emihlanu edlule, kanti e-Ternate ukuxhashazwa kwenziwa kuphela ngo-1991.

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