Indlela Amaphethini KaMagnetic Aqopha Ngayo Ukushintsha Kwepuleti
Cabanga ngephansi lolwandle "njengengobo yomlando" enkulu egcina imikhondo yesikhathi. Hhayi ngendlela ebhaliwe, kodwa ngamaphethini kazibuthe afakwe emadwaleni. La maphethini—imigqa kazibuthe ehambisanayo phansi kolwandle—abe ngobufakazi obuqine kakhulu bokuthi amapuleti e-tectonic ahamba ngempela. Ngale marekhodi kazibuthe, ososayensi bangakwazi ukulandelela ukuthi uqweqwe lolwandle lwakheka nini, ukuthi ukusabalala kwephansi lolwandle kwenzeke ngokushesha kangakanani, nokuthi amapuleti oMhlaba ashintsha kanjani eminyakeni eyizigidi.
Uzibuthe Womhlaba kanye "Nekhampasi" Yemvelo Emadwaleni
Umhlaba unensimu yamagnetic yomhlaba wonke efana ne-giant bar magnet. Imigqa yamandla yamagnetic iphuma eduze kwe-magnetic south pole bese ingena eduze kwe-magnetic north pole. Le nsimu yamagnetic ayizinzile: amandla ayo angashintsha, izindawo zezinsika zamagnetic zingashintsha, futhi okubaluleke kakhulu kule ngxoxo—ngezinye izikhathi iguqula isiqondiso (ukuguqulwa kwe-geomagnetic). Lapho kwenzeka ukuguquka, isiqondiso sensimu yamagnetic yoMhlaba sishintsha ama-degree angu-180: ikhampasi eyayikhomba "enyakatho" manje ikhomba "eningizimu" (ngomqondo wamagnetic).
Ngakho-ke lokhu kuhlobene kanjani namatshe? Amatshe amaningi, ikakhulukazi lawo atholakala ku-magma, aqukethe amaminerali amagnetic njenge-magnetite (Fe₃O₄). Lapho i-magma iphola futhi iphenduka idwala eliyi-igneous, amaminerali amagnetic angaphakathi kwayo "avala" indlela yensimu yamagnetic yoMhlaba lapho iqina. Le nqubo ibizwa ngokuthi i-remanent magnetization. Ngamanye amazwi, amatshe ayisi-igneous akhiwe ngesikhathi esithile angasebenza njengabalogi bedatha: ukugcina indlela yensimu yamagnetic yoMhlaba ngesikhathi azalwa ngaso.
I-Mid-Ocean Ridge: Ifektri Entsha Yokugoba
Isihluthulelo serekhodi likamagnetic lokunyakaza kwamapuleti yi-mid-ocean ridge. Lolu uchungechunge lwezintaba ezingaphansi kwamanzi ezakha emingceleni yamapuleti ahlukene, lapho amapuleti amabili ehlukana khona. Njengoba amapuleti ehlukana, i-magma evela ku-mantle iyaphakama ukuze igcwalise igebe, bese iqina ibe uqweqwe olusha lolwandle. Le nqubo eqhubekayo ibizwa ngokuthi ukusabalala kolwandle.
Ngenxa yokuthi uqweqwe olusha luhlala lwakheka emagqumeni aphakathi nolwandle, phansi kolwandle kufana nebhande lokuhambisa: omncane uphakathi nendawo (emqansweni), bese ekhula njengoba ehamba aye kwesobunxele nakwesokudla. "Ungqimba" ngalunye loqweqwe olwakhiwe ngesikhathi esithile luqopha isiqondiso sensimu yamagnetic yoMhlaba ngaleso sikhathi. Uma insimu yamagnetic ijwayelekile phakathi naleso sikhathi, amatshe azofakwa uqweqwe ngendlela evamile; uma kuyisikhathi sokuguquka, amatshe azofakwa uqweqwe ngendlela ehlukile.
Imivimbo Yama-Magnetic Ehambisanayo: Izimpawu Zeminwe Zokwanda
Lapho ososayensi bedweba amamephu ezimo ezingavamile zikagesi phansi kolwandle besebenzisa ama-magnetometer adonswayo, bathola iphethini emangalisayo: amabhande ezimo ezingavamile zikagesi ahamba ngokuhambisana nezintaba eziphakathi kolwandle futhi ahlelwe ngokulinganayo kuzo zombili izinhlangothi. Lawa mabhande ayeshintshana phakathi kokuqondisa "okujwayelekile" kanye "nokuhlanekezelwe".
Kungani kwenzeka iphethini yokubopha? Ngoba uqweqwe lolwandle luhlala lukhona, kuyilapho insimu yamagnetic yoMhlaba ngezinye izikhathi ivamile futhi ngezinye izikhathi iphenduka. Cabanga ngemigqa yokudweba ebhandeni lokuhambisa: lapho kufakwa upende omnyama, kwakheka ibhendi elilodwa; lapho kufakwa upende omhlophe, kwakheka elinye ibhendi; njalo njalo. Phansi kolwandle, "upende" lowo yi-polarity yensimu yamagnetic. Lapho i-magma iqina emagqumeni aphakathi nolwandle, iqopha i-polarity yamanje, bese ithathwa njengoba amapuleti ehamba. Ngenxa yokuthi ukusabalala kwenzeka kuzo zombili izinhlangothi ngokulinganisela okulinganiselwe, iphethini efanayo yokubopha ivela kuzo zombili izinhlangothi zommango—okudala ukulingana okuhlukile kakhulu.
Le ndlela yokulinganisa iwubufakazi obuqinile bokuthi phansi kolwandle kuyanyakaza futhi kuvuselelwa njalo. Iphinde iphendule umbuzo omdala: ungqimba oludala lolwandle luyaphi? Impendulo: ekugcineni luncishiswa ngaphansi kwamanye amapuleti ezindaweni zokunciphisa, luphinde lusetshenziswe lubuyiselwe emuva endaweni ende.
Ikhalenda LikaMagnetic: Ukuguqula Amaphethini Abe Yisikhathi
Amaphethini kazibuthe awabonisi nje kuphela ukuthi amapuleti ayahamba, kodwa futhi avumela isikhathi sokuqopha. Ososayensi bakhe isikali sesikhathi se-geomagnetic polarity esekelwe kudatha evela ku-lava yomhlaba engalinganiswa ngezinsuku kusetshenziswa izindlela ze-radiometric (isb., i-potassium-argon noma i-argon-argon). Lesi sikali sibala zonke izikhathi ze-polarity evamile neyangemuva eminyakeni eyizigidi edlule.
Uma amaphethini okubamba umugqa ongaphezulu kolwandle eqhathaniswa nesikhathi sokuguquka komhlaba wonke, ibhendi ngayinye "ingalinganiswa" nesikhathi esithile. Kufana nokufanisa ibhakhodi: ukulandelana okufanayo kwamabhendi kubonisa ukulandelana kwesikhathi okufanayo. Ngakho-ke, ososayensi banganquma ubudala boqweqwe lolwandle endaweni ethile ngokumane nje basebenzise iphethini yalo yamagnetic.
Ukulinganisa Ijubane Lokushintsha Kwepuleti
Uma sekwaziwa ubudala boqweqwe, isinyathelo esilandelayo ukukala ukuthi amapuleti ahamba ngokushesha kangakanani. Indlela ilula ngomqondo:
1. Linganisa ibanga letheyiphu elinobuthi kusukela ku-axis yomugqa ophakathi nolwandle (lapho uqweqwe lwakheka khona).
2. Nquma ubudala betheyiphu kusukela esikalini sokuguqula amandla kagesi.
3. Isivinini sokunwebeka = ibanga / isikhathi.
Isibonelo, uma ibhande elakhiwe eminyakeni eyizigidi ezi-5 eyedlule liqhele ngamakhilomitha ayi-100 ukusuka egqumeni, khona-ke izinga lokusabalala ohlangothini olulodwa lingu-100 km / iminyaka eyizigidi ezi-5 = 20 km ngeminyaka eyizigidi, noma u-2 cm ngonyaka. Ngenxa yokuthi ukusabalala kwenzeka kuzo zombili izinhlangothi, izinga lokuhlukaniswa phakathi kwala mapuleti amabili lingaba kabili kunalokho (kuye ngokuthi incazelo esetshenzisiwe ithini).
Besebenzisa le ndlela, abacwaningi bathole ukuthi izinga lokunyakaza kwamapuleti liyahlukahluka: amanye angamamilimitha ambalwa kuphela ngonyaka, amanye angamasentimitha amaningana ngonyaka—uma kuqhathaniswa nezinga lokukhula kwezinzipho zomuntu.
Ukwakhiwa Kabusha Kwezinkathi Zepuleti Elidlule
Amaphethini kazibuthe nawo asiza ekwakheni kabusha umlando wokuvuleka kolwandle kanye nokukhukhuleka kwezwekazi. Njengoba i-Atlantic iqala ukuvuleka, kwadalwa uqweqwe olusha lolwandle eMid-Atlantic Ridge. Amabhande kazibuthe agcinwe phansi kwe-Atlantic manje aqopha indlela i-Afrika neMelika ezahlukana ngayo kancane kancane. Ngokuhlobanisa iminyaka yamabhande, indawo yomqolo, kanye nokwakheka kwamapuleti, ososayensi bangabuyisela emuva “i-movie” ye-tectonic emuva: belinganisa izindawo zamazwekazi eminyakeni eyizigidi edlule.
Ngaphezu kwalokho, izinguquko ekuqondeni kwe-ridge noma ukungahleleki kwamaphethini okubamba kunganikeza izinkomba zokushintsha kwamandla e-tectonic, ukushintsha kokunyakaza kwepuleti, noma izehlakalo ezifana nokugxuma kwe-ridge. Ngakho-ke, irekhodi lamagnetic alikho nje ngesivinini, kodwa futhi nendlela ukuguquguquka kohlelo lwe-tectonic okushintsha ngayo ngokuhamba kwesikhathi.
Kungani Lobu Bufakazi Buqine Kangaka?
Ngaphambi kokutholakala kwamaphethini kazibuthe angaphansi kolwandle, umqondo wokukhukhuleka kwezwekazi (owaphakanyiswa ngu-Alfred Wegener) waliwa kabanzi ngoba kwakungekho ndlela noma ubufakazi obuqinile bokuchaza ukuthi amazwekazi anganyakaza kanjani. Amamephu emigqa kamazibuthe alinganayo anikeze ubufakazi obunobuningi kanye nobomhlaba wonke: iphethini efanayo yatholakala olwandle oluningi, ehambisana nokuguqulwa kwensimu kamazibuthe yoMhlaba nakho okuqoshwe emadwaleni asemhlabeni, futhi iyahambisana nomqondo wokuthi uqweqwe olusha luzalwa ezindaweni eziphakathi kolwandle futhi lulahleke ezindaweni ezingaphansi komhlaba.
Lobu bufakazi buyalinganiswa futhi. Awuboni nje ukuthi into ethile iyafanelana; ungakwazi ukubala ubudala bayo kanye nesivinini sokunyakaza kwayo. Yilokhu okwenza i-paleomagnetism yaphansi kolwandle yaba yingqophamlando ebalulekile ekuzalweni kwenkolelo-mbono yesimanje ye-plate tectonics maphakathi nekhulu lama-20.
I-Penutup
Amaphethini kazibuthe phansi kolwandle ayirekhodi lomlando woMhlaba ogcinwe edwaleni. Iqembu ngalinye lezinto ezingavamile kazibuthe liqopha isiqondiso sensimu kazibuthe njengoba uqweqwe lwakhiwa, futhi ngenxa yokuthi uqweqwe lolwandle lusuka eziqongweni eziphakathi kolwandle, amaphethini ahlelwe kahle futhi alingana. Ngokuwafanisa nesilinganiso sokuguquka kwamagnetic, ososayensi banganquma ubudala boqweqwe, babale izinga lokusabalala, futhi bakhe kabusha ukunyakaza kwamapuleti eminyakeni eyizigidi. Kusukela kulezi "zingqimba" ezingabonakali, sifunda ukuguquka kwamapuleti—ubufakazi bokuthi ubuso boMhlaba buyisistimu ephilayo, ehambayo, futhi eshintsha njalo.
Uma ufisa, ngingangeza umfanekiso womqondo wetheyiphu yamagnetic (umdwebo olula), noma ngiguqule lesi sihloko ngesitayela esithandwayo (esilula) noma sesayensi (esinobuchwepheshe kakhulu) njengoba kudingeka.
