Kaʻina Hana Hoʻokumu Waiho Placer
ʻO nā waihona placer kahi ʻano waihona mineral i hoʻokumu ʻia ma o ka hoʻohuihui ʻana o nā mea waiwai nui ma muli o nā mana exogenous e like me ka weathering, erosion, transportation, a me ka waiho ʻana e ka wai a i ʻole ka makani. Hoʻolālā pinepine ʻia kēia mau waihona no ka eli ʻana no ka mea hiki iā lākou ke loaʻa nā mineral waiwai nui e like me ke gula, cassiterite (tin ore), zircon, rutile, ilmenite, monazite, a me nā pōhaku makamae. ʻO ke ʻano nui o nā waihona placer, ʻo ia ka hoʻohuihui ʻia ʻana o nā mineral kaumaha ma nā wahi kikoʻī, i hoʻokaʻawale ʻia mai nā mineral māmā i maʻalahi ke lawe ʻia e nā au.
Kūkākūkā kikoʻī kēia ʻatikala pehea e hoʻokumu ʻia ai nā waihona placer, e hoʻomaka ana mai ka pōhaku kumu a hiki i ke kūkulu ʻia ʻana o nā papa o nā minerala kaumaha i loko o ke kaiapuni waiho ʻana.
1. Nā Kumu Minerala a me nā Pōhaku Kumu
Hoʻomaka ke kaʻina hana o ka waiho ʻana o ka placer me ke alo o nā pōhaku kumu i loaʻa nā minelala waiwai nui. No ka laʻana, loaʻa pinepine ke gula mai nā aa quartz hydrothermal, cassiterite mai ka granite a i ʻole greisen, a me nā minelala one hao (ilmenite-magnetite) mai nā pōhaku igneous mafic a me metamorphic. Loaʻa kēia mau pōhaku kumu ma nā wahi uka, nā mauna, a i ʻole nā wahi pōhaku i hōʻike ʻia i hala i ka wā.
Hoʻopuehu pinepine ʻia nā minelala waiwai nui i loko o ka pōhaku makua a hoʻopaʻa ʻia paha i loko o nā ʻano kikoʻī. I mea e lilo ai i waihona placer, pono e hoʻokaʻawale kino ʻia kēia mau minelala mai ka pōhaku kikowaena a laila e hana i ka hoʻokaʻawale kūlohelohe i ka wā o ka lawe ʻana.
2. Ke ʻAno ʻĀina: Ke Hoʻokuʻu ʻana i nā Minerala Waiwai
He kahua koʻikoʻi ka hoʻoilo ʻana no ka mea e wāwahi ia i nā pōhaku a hoʻokuʻu i nā hua mineral. Hiki ke hana ʻia ka hoʻoilo ʻana ma nā ʻano penei:
– Ke ʻano kino (mekanika): haki nā pōhaku i nā ʻāpana liʻiliʻi ma muli o nā loli o ka mahana, ka hau-hoʻoheheʻe ʻana o ka wai, a i ʻole ka hana tectonic a me ke koʻikoʻi.
– Ke ʻano kemika: hoʻoheheʻe ʻia a loli paha kekahi mau minelala i mau minelala hou e like me ka lepo ma o nā kaʻina hana o ka oxidation, hydration, a i ʻole carbonation.
– Ke ʻano o ka hoʻoilo olaola: kōkua nā aʻa o nā mea kanu a me nā microorganism i ka wikiwiki o ka haki ʻana o nā pōhaku.
ʻO ke ʻano maʻamau, kūpaʻa nā minelala placer i ka hoʻololi ʻana o ke kemika a loaʻa iā lākou ka paʻakikī a me ke kūpaʻa kiʻekiʻe. ʻO ke gula, no ka laʻana, he inert loa a ʻaʻole reactive; kūpaʻa nō hoʻi ka cassiterite. No laila, ʻoiai ke loli nei nā minelala ʻē aʻe a me ka disintegration, noho mau kēia mau minelala kaumaha ma ke ʻano he mau hua manuahi.
3. Ka ʻino ʻana a me ka hoʻokuʻu ʻana o nā mea i loko o ka ʻōnaehana halihali
Ma hope o ka hoʻonāwaliwali ʻana o ka ʻino i ka pōhaku, ʻo ke kaʻina hana aʻe, ʻo ia ka ʻino ʻana, ka pau ʻana a me ka wehe ʻana i nā mea mai kona wahi mua. Hiki mai ka ʻino ʻana ma muli o ke kahe ʻana o ka wai ua, nā muliwai, nā ʻāina heʻe, a i ʻole nā ale e poʻi ana i ke kahakai.
E komo nā mea i hoʻokuʻu ʻia i nā ʻōnaehana halihali e like me nā muliwai a i ʻole nā au o ke kahakai. I kēia pae, ʻo ka nui o ka hua, ke ʻano o ka hua, a me ka nui o nā minelala e hoʻopilikia nui i ke ʻano o ka neʻe ʻana o nā minelala. ʻO kēia ka hoʻomaka ʻana o ka hoʻokaʻawale kūlohelohe.
4. Ka Halihali: Ke Kuleana o ka Wai a me ka Ikehu Kahe
Hoʻokumu ʻia ka hapa nui o nā waihona placer e ka lawe ʻana o ka wai, ʻoiai nā muliwai a me nā ʻōnaehana kahakai. I ke kahe ʻana o ka wai, neʻe nā mea sedimentary ma o kekahi mau ʻano hana:
– Hoʻokuʻu ʻia: nā ʻāpana liʻiliʻi e kau ana i loko o ka wai.
– Ka paʻakai: lele nā hua one ma luna o ka moena o ka muliwai.
– Ke kuʻi ʻana: ʻōwili/kauo nā hua nui a kaumaha paha ma ka lalo.
ʻO nā minelala kaumaha e like me ke gula he kiʻekiʻe ko lākou density (ma kahi o 19,3 g/cm³), ʻoi aku ke kiʻekiʻe ma mua o ka quartz (ma kahi o 2,65 g/cm³). ʻO ka hopena, ʻano wikiwiki ke gula e noho a kokoke i ka lalo o ke kahawai. ʻO nā minelala māmā, ma ka ʻaoʻao ʻē aʻe, ʻoi aku ka maʻalahi o ka lawe ʻia ʻana i kahi mamao aku i ke kau ʻana.
Eia naʻe, ʻaʻole wale ka lawe ʻana i ka mea e hoʻoneʻe; "hoʻokaʻawale" pū kekahi iā ia. ʻO ka mamao o ka lawe ʻia ʻana o kahi mineral, ʻoi aku ka maikaʻi o kona nui a me ka poepoe o kona ʻano. Loaʻa pinepine nā hua gula placer ma ke ʻano he flakes, nā hua pālahalaha, a i ʻole nā nuggets, ma muli o ka mamao i lawe ʻia a me ke ʻano abrasion.
5. Ka Hoʻokaʻawale ʻana a me ka Hoʻohuihui ʻana o nā Minerala Kaumaha
ʻO ke kumu o ka hoʻokumu ʻana o ka waihona placer ʻo ia ka hoʻohuihui ʻana o nā minelala kaumaha ma o ka hoʻokaʻawale hydrodynamic. Hiki mai ka hoʻohuihui ma muli o nā ʻokoʻa i loko o:
– Ka nui
- Ka nui a me ke ʻano o ka palaoa
– Ka wikiwiki o ke kahe ʻana a me ka haunaele
Ke emi iho ka ikehu kahe—no ka laʻana, ma nā ʻāpana muliwai e hoʻonui ana, nā piʻo, ma hope o nā pōhaku nui, a i ʻole ke hoʻomaka ka emi ʻana o ka wai kahe—e waiho wikiwiki ʻia nā sediments kaumaha ma mua o nā sediments māmā. Hana hou ʻia kēia kaʻina hana, ʻoiai i nā kau kahe, kahi e lawe mai ai i ka nui o nā mea hou, a ukali ʻia e kahi pae waiho ʻana i ka wā e emi ai ke kahe.
Ma muli o kēia hana hou ʻana, lilo nā minelala kaumaha i mea paʻa nui ma kekahi mau papa, e hana ana i nā "pay streaks" i ka hana ʻeli gula alluvial: nā papa waiwai gula e kokoke ana i ka lalo o ka sediment, ma luna pono o ka pōhaku moe a i ʻole ma luna o kahi papa o ka ʻiliʻili nui.
6. Kaiapuni Hoʻokaʻawale Waihona Placer
Hiki ke hoʻokumu ʻia nā waihona placer ma nā ʻano ʻano like ʻole, nona nā ʻano ponoʻī:
a. Ka Muliwai Placer (Fluvial Placer)
ʻO nā wahi hoʻoneʻe muliwai nā mea maʻamau. ʻO nā wahi punahele no nā nui o nā minerala kaumaha:
– Piʻo o ka muliwai o loko (kaʻa kiko)
– Nā māwae a me nā māwae i loko o ka pōhaku moe kahi i “paʻa” ʻia ai nā minelala kaumaha
– ʻO ka ʻāpana ma hope o nā mea pale e like me nā pōhaku nui
– Nā ʻanuʻu muliwai kahiko e hoʻopaʻa ana i ke ala o nā muliwai kahiko
ʻOi aku ka paʻa o nā waihona ma nā ʻanuʻu muliwai a hiki ke lilo i mau pahuhopu no ka hana ʻeli nui ʻana no ka mea ʻaʻole lākou i loaʻa mau ma nā kahawai muliwai e hana mau ana.
b. Kahi Hoʻonoho Kahakai
Ma nā kahakai, nā nalu a me nā au o ke kahakai e hoʻokaʻawale ikaika i ka lepo. Hoʻopili pinepine ʻia nā minelala kaumaha e like me ka ilmenite, rutile, zircon, a me ka monazite i loko o ke "one ʻeleʻele." Holoi pinepine ʻia ka lepo māmā e nā nalu a me nā au i ke kai, ʻoiai e noho ana nā minelala kaumaha a hōʻiliʻili.
c. Mea Hoʻonoho Kai Pāpaʻu (Mea Hoʻonoho Kai)
Loaʻa kekahi mau placers mai ke kahakai a i ʻole nā mea muliwai i waiho ʻia ma nā papa kai pāpaʻu. Hana nā nalu, nā au kai, a me nā ʻino ma ke ʻano he mau mea hoʻokaʻawale e hiki ai ke hana i nā papa o nā minelala kaumaha ma ka papahele o ke kai.
d. Mea Hoʻonoho Makani (Mea Hoʻonoho Eolian)
ʻOiai ʻaʻole i maʻamau, hiki i ka makani ke hoʻokumu i nā wahi i hoʻonoho ʻia ma nā wahi neoneo a i ʻole nā kahakai one. Hoʻoneʻe maʻalahi ka makani i nā hua māmā, e waiho ana i nā minelala kaumaha ma hope ma ke ʻano he mau waihona lag.
7. Ke Kuleana o nā Pahele Kūlohelohe i ka Hoʻohuihui Placer
No ka hana ʻana i nā waihona placer waiwai i nā mineral, pono nā pahele e pale aku i nā mineral kaumaha mai ka lawe ʻia ʻana e ke au. Hiki i kēia mau pahele ke komo pū me:
– ʻIli pōhaku moe ʻaʻole like (nā lua liʻiliʻi, nā māwae, a i ʻole nā ʻanuʻu)
– He papa o ka ʻiliʻili nui e hana ana e like me ka "sieve"
– Nā ʻano hoʻoheheʻe e like me nā ripples, cross-molding, a i ʻole nā kaola
– Nā mea kanu a me nā pale kūlohelohe e hoʻolohi i ke kahe ʻana
ʻO ke gula, no ka laʻana, hōʻiliʻili pinepine ʻia ma nā ʻāpana hohonu loa o ka lepo no ka mea ʻo kona kaumaha ke kumu e "piho" ai ma waena o ke one a hiki i ka pōhaku kumu. No laila, kuhikuhi pinepine ka hana ʻeli placer i nā papa haʻahaʻa loa.
8. Kanu ʻana, ka hoʻopaʻa ʻana, a me ke kūkulu ʻana i nā waihona paʻa mau loa
I ka hala ʻana o ka manawa, hiki ke uhi ʻia nā waihona placer e ka sediment hou, hoʻopaʻa ʻia, a lilo i ʻoi aku ka oʻo ʻana o ka honua. I nā manawa lōʻihi, hiki i nā neʻe ʻana o ka muliwai a i ʻole nā loli o ka ʻilikai ke hoʻokiʻekiʻe i nā waihona i loko o nā ʻanuʻu a hoʻoluʻu paha iā lākou i loko o ke kaiapuni kai.
ʻOiai ʻaʻole i like ka lithification o nā waihona placer me nā waihona sedimentary kahiko, hiki i kekahi mau placers kahiko ke lithify i loko o nā conglomerates. ʻO kahi laʻana i kūkākūkā pinepine ʻia ma ka geology ʻo ia nā conglomerates waiwai gula i loko o nā ʻōnaehana sedimentary kahiko, e hoʻopaʻa ana i kahi kaʻina hana like, e hana wale ana i ka wā kahiko geological.
Ka hopena
ʻO ke kūkulu ʻia ʻana o nā waihona placer ka hopena o kahi moʻo lōʻihi o ka hoʻomake pinepine ʻia ʻana o nā pōhaku kumu, ka ʻino ʻana, ka lawe ʻana, ka hoʻokaʻawale ʻana, a me ka waiho ʻana. ʻO kahi kumu nui i ka waiwai waiwai o nā placers ʻo ia ka hiki o ke kūlohelohe ke hoʻopili i nā minelala kaumaha a kūpaʻa—e like me ke gula, cassiterite, a me nā minelala one kaumaha—ma nā wahi kikoʻī e hana ana ma ke ʻano he mau pahele sediment. Hāʻawi nā muliwai, nā wahi kahakai, a me nā wahi kai pāpaʻu i nā kūlana ikehu ikaika e hiki ai i ka hoʻopili ʻana o nā minelala ke hana kūlohelohe.
Ma ka hoʻomaopopo ʻana i kēia mau kaʻina hana, hiki i nā kānaka ʻepekema honua a me nā mea hana maina ke wānana i kahi e hiki mai ana o nā waihona placer, loiloi i ka maikaʻi o nā waihona, a hoʻolālā i nā ʻano hana ʻimi a me ka hana maina ʻoi aku ka maikaʻi a me ke kuleana no ke kaiapuni.
