Hydrothermal Ore Deposits.(ေရပူျပဳသတၱဳရိုင္းသိုက္မ်ား)သည္ ေနာက္ျဖစ္ သတၱဳရိုင္းသိုက္ (The Epigenetic Ore Deposits)မ်ား ျဖစ္ၾကပါသည္။ အနယ္က်ေက်ာက္လႊာမ်ားျဖစ္ထြန္းမႈတြင္ ပို႔ခ်အနယ္အလႊာမ်ားႏွင့္အတူ တၿပိဳင္တည္းပူတြဲပို႔ခ်ျဖစ္ထြန္းေသာ သတၱဳရိုင္းသိုက္အမ်ိဳးအစား (Syngenetic Ore Deposits)မ်ားမဟုတ္ၾကေခ်။ ေရပူျပဳသတၱဳရိုင္းသိုက္မ်ား တြင္ေရႊ၊ ေငြ၊ ခဲ၊ သြပ္၊ ေၾကးနီ၊ ျပဒါးတြင္းထြက္မ်ားျဖစ္ထြန္းၾကပါသည္။ တိုးဝင္ေက်ာက္ရည္ပူမ်ားသည္ အဓိကေက်ာက္ျဖစ္တြင္းထြက္မ်ား (Rock Forming Minerals)အျဖစ္အခဲဖြဲ႕ပံုေဆာင္ၿပီးေသာ အခါ၊ ေနာက္ဆံုးအဆင့္ပံုေဆာင္ေအးခဲခ်ိန္အတြင္း၊ ၾကြင္းက်န္ေက်ာက္ရည္ပူမ်ား (Residual Fluid) က်န္ရွိထြက္ေပၚလာပါသည္။ ၄င္းအရည္မ်ားထဲတြင္ သတၱဳျဖစ္ထြန္းမည့္ေပ်ာ္ဝင္ရည္မ်ားႏွင့္ ေရေငြ႕အပူမ်ားပါေပ်ာ္ရည္မ်ား (Hot Watery Solution) ပါဝင္ေနၾကပါသည္။ ၄င္းေရာရာေပ်ာ္ရည္အပူမ်ားကိုသတၱဳေရပူျပဳေပ်ာ္ရည္ (Hydrothermal Solution) ဟုေခၚပါသည္။ ထိုေပ်ာ္ရည္မ်ားသည္ ပိတ္ရန္ေနသာေက်ာက္လႊာမ်ား၏ အက္ကြဲေၾကာင္းမ်ား၊ အေပါက္မ်ား အတြင္းသို႔ေရြ႕လ်ားတိုးဝင္၍ ေတြ႕ထိရာေက်ာက္မ်ားအားအရည္ေဖ်ာ္ ေပ်ာ္ဝင္ေစျခင္းႏွင့္အတူ အခဲဖြဲ႕ေအးခဲၾကပါသည္။
ထိုကဲ့သို႔ျဖစ္စဥ္တြင္
(က)ေရပူျပဳသတၱဳရိုင္းသိုက္မ်ား Hydrothermal Deposits
(ခ) အပူခ်ိန္အလယ္အလတ္ရွိသတၱဳရိုင္းသိုက္မ်ား Mesothermal Deposits
(ဂ)အပူခ်ိန္နိမ့္ သတၱဳရိုင္းသိုက္မ်ား Epithermal Deposits
အသီးသီးျဖစ္ေပၚလာၾကေၾကာင္းသိရွိရပါသည္။
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အပူခ်ိန္နိမ့္ သတၱဳရိုင္းသိုက္မ်ား Epithermal Deposits
၄င္းသည္အပူခ်ိန္နိမ့္ Low Temperature တြင္ျဖစ္ေပၚေသာ သတၲဳ႐ိုင္းသိုက္ ျဖစ္ပါသည္။ တိုးဝင္မီးသင့္ေက်ာက္စိုင္ထုႏွင့္ အလြန္ေဝးေသာေနရာ တြင္ျဖစ္ထြန္းပါသည္။ အပူခ်ိန္ (<300ºC)၊ အနက္ <1 km တြင္ျဖစ္ေပၚပါသည္။
Ore deposits: Epithermal Deposits movie: https://www.youtube.com/watch?v=e33EeVOZOeQ
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Epithermal Deposits ကို (၃) မ်ဳိးခြဲျခားထားၿပီး အေတြ႔ရအမ်ားဆံုး (၂)မ်ဳိးမွာ-
၁. Low sulfidation (LS) - (Adularia-sericite)
@ Deposit form = Open-space veins dominant, stockwork ore common, Disseminated and replacement ore minor
@ Textures = Veins, cavity filling (bands, colloforms, druses), breccias
@ Ore minerals = Pyrite, electrum, gold, sphalerite, galena (arsenopyrite)
@ Gangue = Quartz, chalcedony, calcite, adularia, illite, carbonates
@ Metals = Au, Ag, Zn, Pb (Cu, Sb, As, Hg, Se)
@ Others = usually small-moderate in size; but high grade relatively narrow veins, steeply dipping; depth limited by boiling zone (seldom >350m vertical extent); likely to be mined from underground, unless swarm of veins
. . . . . .
၂. High sulfidation (HS) - (Acid-sulfate)
@ Deposit form = Disseminated ore dominant, replacement ore common, Stockwork ore minor, veins commonly subordinate
@ Textures = Wallrock replacement, bx, veins
@ Ore minerals = Pyrite, enargite, chalcopyrite, tennantite, covellite, gold, tellurides
@ Gangue = Quartz, alunite, barite, kaolinite, pyrophyllite
@ Metals = Cu, Au,Ag, As (Pb, Hg, Sb, Te, Sn, Mo, Bi)
@ Others = Size can be large; often ‘T’ shaped; roots may extend to >l 000m depth
(Although usually less); If low grade, disseminated mineralization; likely to be mined by open pit
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က်န္အမ်ဳိးအစား(၁)မ်ဳိးမွာ -
၃. Intermediate-sulfidation
@ Generally veins and breccias, like Low-sulfidation epithermals but coarser banding
@ But may contain alunite like High-sulfidation epithermals
@ In addition to gold, usually contain significant silver, lead (galena), zinc (sphalerite) at depth
@ Gold and silver deposition is controlled by boiling. Base metals mainly by fluid mixing/cooling.
@ Others = Gold near top, becoming more silver and then dominantly lead-zinc rich at depth; usually steep veins but may have flat splays (e.g. Pitarilla); veins can be long and continuous; silver-lead-zinc mineralization can extend to significant depths (e.g. at Fresnillo lead-zinc extends from 300 to 900m); usually mined from underground although flat portions can be open pitted.
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ျမန္မာႏိုင္ငံရွိ ထင္ရွားေသာ Epithermal Deposits
1. Monywa Cu Deposit - High Sulfidation
2. Myesetaung, Letpadan - Epithermal Vein
3. Taungni, SW of Mt. Popa - High Sulfidation
Credit Win Hlaing; Compiled by (GNS)
Epithermal Ore Deposits ႏွင့္ ၄င္း၏ ထူးျခားခ်က္းမ်ား
Hydrothermal Ore Deposits.(ေရပူျပဳသတၱဳရိုင္းသိုက္မ်ား)
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