Mokhoa oa ho Fumana Lilemo tsa Masalla ka Radiometry
Ho fumana lilemo tsa mesaletsa ea lintho tsa khale ho bohlokoa bakeng sa ho utloisisa nalane ea bophelo Lefatšeng. E 'ngoe ea mekhoa e sebetsang ka ho fetisisa ea ho fumana nako ea mesaletsa ea khale ke radiometry. Mokhoa ona oa saense o sebelisa melao-motheo ea ho bola ha mahlaseli a kotsi ho hakanya lilemo tsa majoe le mesaletsa ea lintho tsa khale ka ho nepahala ho ikhethang. Sehloohong sena se felletseng, re tla hlahloba metheo ea ho bala nako ka radiometric, mekhoa ea radiometric e sebelisoang haholo, le mehato e amehang ho fumaneng lilemo tsa mesaletsa ea lintho tsa khale ka radiometry.
Ho Utloisisa ho Intša ka Radiometric
Ho bala nako ka radiometric ho itshetlehile molao-motheong wa hore di-isotope tse itseng tsa dielemente ha di tsitsa mme di bola ho ba dibopeho tse tsitsitseng ha nako e ntse e ya ka lebelo le ka lebellwang. Tshebetso ena e tsejwa e le ho bola ha radioactive. Ka ho lekanya karolelano ya isotope ya motswadi (e sa tsitsang) ho isotope ya moradi (e tsitsitseng) sampoleng, bo-rasaense ba ka bala nako e fetileng ho tloha ha lefika kapa mesaletsa ya dintho tsa kgale e thehwa. Nako ena e fetileng e bitswa "mehla ya radiometric" ya sampole.
Isotope e 'ngoe le e 'ngoe ea mahlaseli a kotsi e bola ka lebelo la eona le sa fetoheng, e khetholloang ka lentsoe le tsejoang e le halofo ea bophelo—nako eo e nkang halofo ea palo e itseng ea isotope ho bola. Mekhoa e fapaneng ea ho bala nako ea isotopic ea sebetsa ho latela lilemo tsa sampole le thepa e teng.
Mekhoa ea Bohlokoa ea Isotopic ho Rating ea Radiometric
1. Ho Intša le Batho ba Bang ka Khabone-14 (Ho Intša le Batho ba Bang ka Radiocarbon)
- Sebaka se Sebetsang: Ho fihlela lilemo tse ka bang 50,000
– Thepa e nang le Letsatsi: Thepa ea tlhaho (mohlala, lesapo, patsi, mashala)
– Molao-motheo: Carbon-14 (^14C) ke isotope ea khabone e nang le mahlaseli a kotsi e bolang ho ba naetrojene-14 (^14N). Lintho tse phelang li fapanyetsana ^14C le sepakapaka khafetsa, empa phapanyetsano ena ea emisa ha sephedi se e-shoa. Ho fumana ^14C e setseng sampole ho thusa ho hakanya lilemo tsa sona.
2. Ho intša le Uranium-Eader
- Mefuta e sebetsang: Ho tloha lilemong tse ka bang limilione tse 1 ho isa ho tse fetang limilione tse likete tse 4.5
– Lisebelisoa tse Hlahisitsoeng ka Letsatsi: Likristale tsa Zircon mafikeng a igneous, li-deposit tse ling tsa sedimentary, calcium carbonate
– Molao-motheo: Li-isotope tsa Uranium (^238U le ^235U) lia bola ka letoto la mehato ho ea ho li-isotope tse tsitsitseng tsa lead (^206Pb le ^207Pb). Ho lekanya karolelano ea uranium-to-lead ho fana ka lilemo tsa sampole.
3. Ho Intša le Potassium-Argon
- Mefuta e Sebetsang: Ho tloha lilemong tse ka bang 100,000 ho isa ho tse fetang limilione tse likete tse 4
– Lisebelisoa tse Hlahisitsoeng ka Letsatsi: Lefika la seretse se chesang (mohlala, basalt, tuff)
– Molao-motheo: Potassium-40 (^40K) e bola ho ba argon-40 (^40Ar). Kaha argon ke khase, e tsoa lefikeng le qhibilihisitsoeng, e netefatsa hore ^40Ar efe kapa efe lefikeng le tiileng ke phello ea ho bola. Ho bapisa karolelano ea ^40K ho ^40Ar ho senola lilemo tsa sampole.
4. Ho Intša ha Rubidium-Strontium
- Mefuta e sebetsang: Ho tloha lilemong tse ka bang limilione tse 10 ho isa ho tse fetang limilione tse likete tse 4
– Lisebelisoa tse Hlahisitsoeng ka Letsatsi: Muscovite, biotite, le liminerale tsa feldspar tsa potassium
– Molao-motheo: Rubidium-87 (^87Rb) e bola ho ba strontium-87 (^87Sr). Ka ho lekanya li-isotope tsena, lilemo tsa ho thehoa ha lefika li ka fumanoa.
Mehato e Amehang ho Rateng ka Radiometric
1. Pokello ea Mehlala
– Sepheo: Bokella disampole tse emelang tse nang le tšilafalo e fokolang.
– Mokhoa: Sebelisa lisebelisoa tse hloekisitsoeng ho bokella mafika kapa mesaletsa ea lintho tsa khale ho tsoa lera le tsebahalang hantle la stratigraphic. Ngola sebaka le maemo a nepahetseng a sampole.
2. Ho Lokisetsa Mehlala
– Sepheo: Lokisetsa disampole bakeng sa tlhahlobo ya isotopic.
– Mokhoa: Hloekisa le ho sila disampole tsa mafika haeba ho hlokahala. Arola diminerale tse itseng (mohlala, zircon bakeng sa ho fumana nako ya uranium-lead) ka mekgwa ya mmele le ya dikhemikhale.
3. Tekanyo ea Likarolelano tsa Isotope
– Sepheo: Fumana dikarolelano tsa isotope tsa motswadi le moradi.
– Mokhoa: Sebelisa lisebelisoa tse kang li-spectrometer tsa boima. Bakeng sa ho bala nako ea carbon-14, hangata ho sebelisoa accelerator mass spectrometer (AMS). Li-isotopic ratio tse nepahetseng ke tsa bohlokoa bakeng sa ho bala lilemo tsa sampole.
4. Palo ea Lilemo
– Sepheo: Fetola dikarolelano tsa isotope hore e be khakanyo ya dilemo.
– Mokhoa: Sebelisa equation ea ho bola:
\[ t = \frac{1}{\lambda} \ln \left( \frac{N_d}{N_p} + 1 \right) \]
moo \( t \) e leng dilemo, \( \lambda \) ke ntho e sa fetoheng ya ho bola, \( N_d \) ke palo ya di-isotope tsa moradi, mme \( N_p \) ke palo ya di-isotope tsa batswadi. Ntho e sa fetoheng ya ho bola e amana le halofo ya bophelo ba isotope.
5. Netefatso ea Tšebelisano
– Sepheo: Netefatsa botšepehi ba khakanyo ea lilemo.
– Mokhoa: Bapisa liphetho le mekhoa e meng ea ho intša 'me u hlahlobe hore na li lumellana le moelelo oa jeoloji. Mehlala le mekhoa e mengata e fana ka letsatsi le tiileng haholoanyane.
Likopo le Meeli
dikopo
– Paleontology: Ho fumana nako ea mesaletsa ea lintho tsa khale ho utloisisa linako tsa ho iphetola ha lintho.
– Thuto ea lintho tsa khale: Ho fumana lilemo tsa lintho tsa khale tsa khale.
– Jeoloji: Ho ithuta nalane le ho thehoa ha bokaholimo ba Lefatše.
sheba mefokolo ea
– Tšilafalo: Ho hlahisoa ha lintho tse tsoang kantle ho ka sotha liphetho.
– Likhopolo: E hloka likhakanyo mabapi le maemo a pele le litsamaiso tse koetsoeng.
– Lithibelo tsa Thepa: Mekhoa e meng e sebetsa feela ho thepa e itseng kapa mekhahlelo ea lilemo.
Le hoja radiometry e sebetsa hantle haholo, ke karolo e 'ngoe ea papali e pharalletseng ea ho utloisisa nalane ea polanete ea rona. Ka ho e kopanya le mekhoa e meng ea ho ipehela nako le moelelo oa jeoloji, bo-rasaense ba ka haha setšoantšo se felletseng sa nako e fetileng.
