Nzira dzeElectromagnetic mukutsvaga zvicherwa
Kutsvaga zvicherwa inzira yekuedza kunzwisisa "zviri pasi pevhu" pasina kutanga wachera. Nekuti kuchera kunodhura uye kune njodzi, matanho ekutanga ekutsvaga anowanzo shandiswa nenzira dze geophysical kuderedza zvinangwa. Rimwe boka rakakosha renzira dze geophysical inzira dze electromagnetic (EM). Nzira idzi dzinoshandisa mhinduro yemagetsi yematombo kuminda yemagetsi neyemagineti kuti dzione nzvimbo dzine zvicherwa, kunyanya idzo dzinofambisa mvura, dzakadai semasulfide makuru, graphite, kana dzimwe nzvimbo dzekuchinja.
Nheyo dzekutanga dzeMagetsi eMagetsi
Nzira dzemagetsi dzinoshanda zvichibva papfungwa ye electromagnetic induction. Kana electromagnetic field ikachinja nekufamba kwenguva, inokonzera magetsi muzvinhu zvinofambisa mhepo pasi pemvura. Iyi induced current inobva yagadzira secondary magnetic field inogona kuyerwa pamusoro kana kubva mumhepo. Musiyano uripo pakati pe "primary" signal (inotumirwa ne source) uye "secondary" signal (inobva pasi pemvura) ndiyo inokosha pakutsanangura kuvapo uye geometry ye conductive bodies.
Zvinhu zvinonyanya kukosha muongororo dzeEM ndeizvi:
– Kufambisa magetsi (σ) kana kuti kupindirana kwayo, kumisa magetsi (ρ). Kucheneswa kwesulfide kunowanzo fambisa magetsi.
– Kupinda kwesimba remagineti (μ), iro rinokanganisa kupindura kweminda yemagineti, kunyanya mumatombo ane zvicherwa zvemagineti zvakawanda.
– Dielectric permittivity (ε), ine simba guru pamafrequencies akakwira zvikuru, semuenzaniso muground penetrate radar (GPR).
Nekuchinja maparamita ekuongorora akadai sehuwandu, chimiro chemafungu, uye daro pakati pemasensa, nzira yeEM inogona "kuona" kudzika kwakasiyana uye zviyero zvezvinangwa.
Kupatsanurwa kweNzira dzeEM: Dzisingashande uye Dzinoshanda
Kazhinji, nzira yeEM yakakamurwa kuita maviri:
1. Nzira dzisingashande, dzinoshandisa zviwanikwa zvemumunda zvinobva mukuita kweionospheric kana mheni. Mienzaniso yakakosha ndeye magnetotellurics (MT) uye audio-magnetotellurics (AMT). Nzira idzi dzakakodzera kuferefeta kudzika kukuru kusvika kugomba risina kudzika, kusanganisira masisitimu emvura inopisa munzvimbo dzakasiyana.
2. Nzira dzinoshanda, dzinoshandisa zvinhu zvakagadzirwa zvakaita semakoira ekutumira kana magetsi anodzorwa. Apa ndipo panowanzo shandiswa kutsvaga zvicherwa EM, semuenzaniso FDEM (Frequency-Domain EM), TDEM (Time-Domain EM), uye zvinobva mumhepo zvakaita seAirborne EM.
Frequency-Domain EM (FDEM)
MuFDEM, transmitter inogadzira sinusoidal electromagnetic field pane imwe kana kupfuura frequency. Iyo receiver inozoyera mhinduro maererano nezvikamu zve in-phase uye quadrature. Chikamu che quadrature chinowanzoenderana zvakanyanya ne conductivity, nepo in-phase inogona kukanganiswa ne strong conductors uye magnetic effects.
Zvakanakira FDEM:
- Kuyera nekukurumidza uye zvinobudirira kwemepu isina kudzika-pakati.
- Yakanakira kuyera kusiyana kwemafambiro emagetsi, semuenzaniso nzvimbo dzekuchinja, ivhu remhepo, kana tsvina yegirafiti.
Miganhu yeFDEM:
- Kudzika kwekupinda kwemvura kwakadzikira, zvichienderana nehuwandu hwemvura uye mamiriro enzvimbo.
- Kududzira kunogona kuoma munzvimbo dzine nzira dzakasiyana-siyana dzekupindira (tambo dzemagetsi, fenzi, zvivakwa).
Nguva-Domain EM (TDEM)
TDEM inoshanda nekuisa magetsi emagetsi pakoiri yekutumira uye yozongoerekana yadzima. Kana magetsi apera, simba guru remagineti rinodonha, zvichikonzera magetsi emvura (magetsi emvura) ari pasi pemvura. Aya magetsi emvura anobva aora nekufamba kwenguva, uye kuora uku kunonyorwa neanogamuchira senzira yenguva. "Nguva dzekutanga" dzinowanzo miririra manyuko asina kudzika, nepo "nguva dzekupedzisira" dzichienderana nekudzika kukuru.
Zvakanakira zveTDEM:
- Inoshanda zvikuru pakuona ma conductor akasimba akadai sema sulfide makuru.
- Ine kugona kudzika kuri nani kupfuura magadzirirwo akawanda eFDEM.
- Data rekuora kwenguva rinogona kushandurwa kuita modhi yekufambisa kana kudzika.
Miganhu yeTDEM:
- Inoda dhizaini yakanaka yekuongorora (kutenderera, kurongeka, kugadzika) kuitira kuti chinangwa chive nyore kuverenga.
– Kududzirwa kunogona kukanganiswa nezvinhu zvisingakoshi zvakaita sevhu, mvura yepasi pevhu ine munyu, kana girafiti.
Airborne EM (AEM): Ongororo Inokurumidza Yedunhu
Mukutsvaga kwemazuva ano, Airborne EM (AEM)—ichishandisa maherikoputa kana ndege—ndiyo nzira huru yekukurumidza kufukidza nzvimbo dzakakura. Masensa eEM anosungirirwa mu "shiri" kana furemu pasi peherikoputa, zvichibvumira kuyerwa kwemhepo ivhu nguva dzose munzira yese. AEM inonyanya kubatsira mumatanho ekutanga ekutsvaga, kunyanya munzvimbo dzakaoma, masango akakora, kana nzvimbo dzine madhaka.
Zvakanakira zveAEM:
- Kufukidzwa kwenzvimbo nekukurumidza uye mutengo unonzwisisika pakiromita imwe neimwe yenzvimbo huru.
- Kukwanisa kuona zvinhu zvisina kunaka zvinokonzereswa nemhepo zvinozotanga kutariswa pasi nekuchera.
Miganhu yeAEM:
- Kusimba kwepasi pevhu kunowanzova kwakaderera pane ongororo dzakadzama dzepasi.
– Inonzwa ruzha rwetsika uye kuchinja kwekukwirira kwekubhururuka.
Mashandisirwo Akakosha Mukutsvaga Zvicherwa
Nzira yeEM inozivikanwa zvikuru yekuona miviri inofambisa mhepo, zvichiita kuti inyatsobatsira mune zvinotevera zvinhu uye nharaunda dzezve geology:
1. Sulfide yakakura (VMS, Ni-Cu sulfide, Pb-Zn)
Zvicherwa zvesulfide zvakaita sepyrite, pyrrhotite, chalcopyrite, galena, uye sphalerite zvinowanzova ne conductivity yakanyanya, kunyanya kana zvakabatana. TDEM neAEM zvinoshanda zvikuru pakuona "ma plate-like conductors" anozivikanwa nema sulfides makuru.
2. Nickel sulfide uye komatiite deposits
Nickel sulfide inowanzobatanidzwa ne conductive pyrrhotite, zvichiita kuti EM ive chishandiso chikuru chekutsvaga, chinowanzo sanganiswa nemagineti ne geochemistry.
3. Matombo eGraphite necarbonaceous
Graphite inofambisawo mhepo uye inogona kukonzera kusagadzikana kwakasimba kweEM. Dambudziko nderekuti graphite inogona kuva "nhema" kana chinangwa chikuru chiri sulfide yehupfumi. Saka, EM inowanzo sanganiswa ne geology ne geochemistry kuti ionekwe panobva kusagadzikana.
4. Kugadzirisa uye kugadzira mapu
Nzvimbo dzinochinja mafambiro emvura dzinogona kuwedzera mafambiro emhepo nekuda kwekuumbwa kwemaminerari evhu kana mvura. EM inobatsira kuyera zvivakwa zvezvikanganiso uye kubatana kwe lithologic kunodzora nzira dzemaminerari anoisa minerali.
Kugadzira Ongororo uye Kududzira Data
Kubudirira kweongororo yeEM hakungotsamiri pachinhu chinoshandiswa chete, asiwo pakugadzirwa kweongororo. Zvinhu zvakakosha zvinosanganisira:
– Kutarisa nzira kuenda kwakananga chimiro che geological; nzira yacho inofanira kuenderana nekwakananga chinangwa chekubaya.
– Nzvimbo yekutevera: ongororo dzenharaunda dzinogona kuva 200–400 m, nepo ongororo dzakadzama dzinogona kuva 25–100 m.
– Maparamita ekuwana: sarudzo yemafrequency (FDEM), nguva yekugadzika (TDEM), kurongeka kwe loop (mukati me loop, kunze kwe loop), uye kukwirira kwe sensor (AEM).
Kuti idudzirwe, data reEM rinowanzo gadziriswa: kugadziriswa kwekudzungaira, kusefa ruzha, kuenzana, uye kuchinjika kuti pave nemamodheru ekufambisa e1D/2D/3D. Kuchinjika kwe3D kuri kuramba kuchiwanda nekuda kwekukwanisa kwayo kuratidza chimiro chemiviri inofambisa, asi inoda data remhando yepamusoro uye kushanda nesimba pakuverenga.
Zvakanakira uye Zvisina Kukosha zveEM Method
Zvakanakira zvikuru:
– Inonzwa kucheneswa kwemineralization inofambisa mvura, kunyanya sulfides.
- Inogona kupinda mune imwe nyaya yakawandisa asi ichiona chinangwa chiri pazasi.
- Yakakodzera nhanho dzekutsvaga kubva kumatunhu (AEM) kusvika kune yakadzama (land TDEM).
Miganho mikuru:
– Hazvisi zvicherwa zvese zvehupfumi zvinofambisa mvura (semuenzaniso, goridhe risina muripo mu quartz harisi nguva dzose rinopa EM anomaly yakananga).
– Zvinofambisa zvinhu zvisina basa (ivhu, brine, graphite) zvinogona kutevedzera maitiro ekugadzira mineralization.
- Ruzha rwetsika nemamiriro ekunze zvinogona kuderedza kunaka kwedata.
Mhedziso
Nzira dzemagetsi dzinoshandiswa pakutsvaga zvicherwa zvemazuva ano nekuda kwekugona kwadzo kuona kusiyana kwekushandiswa kwemvura pasi pevhu kunowanzo enderana zvakananga nenzvimbo dze sulfide mineralization kana shanduko. Nehunyanzvi hwakadai seFDEM, TDEM, MT, uye AEM, EM inogona kushandiswa kubva pazvikamu zvedunhu kuenda kuzvinangwa zvekuboora. Kunyange zvazvo ine miganhu uye isinganyatsojeka, kubatanidza EM ne geological mapping, magnetic, gravity, uye geochemical surveys, pamwe nekuongorora kuchera, zvinoguma nekududzira kwakasimba. Pakupedzisira, kukosha kukuru kwenzira dzeEM kuri mukukwanisa kwadzo kukurumidzisa kuita sarudzo—kusarudza zvinangwa zvinonyanya kutarisirwa, kuderedza njodzi, uye kugadzirisa mari yekutsvaga.
