Phakathi kokwakheka komhlaba esikuthola emhlabeni wethu sinawo i-craton. Igama elithi craton lisetshenziselwa ukuhlukanisa ingxenye ezinzile yangaphakathi yoqweqwe lwezwekazi kulezo zifunda ze-orogenic, okungamabhande aqondile okunqwabelana kanye / noma ukuguguleka kwenhlabathi engaphansi kokuncipha kanye / noma ukuphakanyiswa.
Kulesi sihloko sizokutshela konke okudingeka ukwazi mayelana ne-craton, izici zayo nokubaluleka kwayo.
Ukuqhuma kwezwekazi
I-continental crust indala kakhulu futhi igugulekile futhi inamadwala asendulo e-igneous kanye ne-metamorphic. Ama-post-archaic rocks agcina umthwalo omningi ogoqiwe wamadwala e-metamorphic sedimentary rocks. Ezokuqala zisezindaweni eziyisicaba, cishe eziyisicaba, kanti ezokugcina ziyiziNtaba. I-Craton noma i-cratogen (kusuka ku-Greek Kraton, okusho isitsha esiyisicaba kakhulu) yinqwaba yomhlaba efinyelele esimweni esinzima kangaka emlandweni okude wokwakheka komhlaba. Kusukela ngaleso sikhathi, ayizange ihlupheke ukuhlukana noma ukuguqulwa ngenxa yokuthi ayizange ithintwe ukunyakaza kwe-orogenic. Ngalesi sizathu, ama-cratons avame ukuba isicaba, noma abe nama-bas-reliefs ayindilinga, futhi ngokuvamile amatshe amadala. I-craton engaphansi kwamanzi ibizwa ngokuthi ama-nesocratons.
Yini i-craton
Itemu elithi craton lisetshenziselwa ukuhlukanisa izingxenye ezizinzile zangaphakathi zoqweqwe lwezwekazi kumabhande e-orogenic (amaphethelo ezwekazi, ama-sediments kanye nezitsha ze-orogenic), okunqwabelanayo kanye / noma izindawo zokuguguleka kwenhlabathi (izitsha) ezingaphansi kokuwohloka. Futhi / noma uplifts (izintaba). I-craton emaphakathi ebanzi yezwekazi ingakhiwa izihlangu kanye namapulatifomu aphansi, kanye nezisekelo zengilazi. Isihlangu siyingxenye ye-craton, lapho amatshe e-Precambrian atholakala kakhulu phezulu. Ngokuphambene, inkundla yesisekelo imbozwe ama-sediments avundlile nama-sublevels.
Isihlangu siyindawo yezwekazi eyakhiwe ngamatshe akhiwa ngesikhathi se-Precambrian, ayengamboziwe ulwandle. Isihlangu sakhiwe amatshe amadala kakhulu oqweqwe lomhlaba, i-granitization kanye ne-metamorphism. Kusukela emvelaphi yabo, bezinzile futhi bagcina ukuqina kwabo.
Iqiniso lokuthi abakaze bacwiliswe emanzini ngenxa yesiphambeko kungenxa yokuthi baye babhekana nokunyakaza okuqondile kwe-tectonic. Abazange bakuzwe ukugoqa ngoba bamelana nakho konke ukuphonswa okuvundlile. Izihlangu ngokuvamile zingamadwala avuthayo kanye ne-metamorphic avele endaweni enkulu, anezakhiwo ezinzile kanye nemisebenzi embalwa ye-orogenic. Kuzo zonke izimo, Lawa matshe aneminyaka engaphezu kwezigidi ezingu-570 ubudala, kanti ezinye zisukela eminyakeni eyizigidi eziyizinkulungwane ezingama-200 kuya kwezingu-3,5 edlule.
Ngenxa yokuqina kwayo, ukuguguleka kwenhlabathi kwenza isimo sezwe sezihlangu eziningi zezwekazi silingane. Kodwa-ke, ngokuvamile anezindawo ezicishe zibe yi-convex futhi zingazungezwa izindawo ezimbozwe inhlabathi ezibizwa ngokuthi amashalofu ezwekazi. Izindawo ezingenalutho, izinkundla ezimboziwe kanye nezisekelo zekristalu ndawonye zakha ingxenye ezinzile yoqweqwe lwezwekazi olwakha isihlangu noma i-craton.
Izihlangu nokubaluleka kwazo
Isihlangu ngokuvamile siwumgogodla wezwekazi, futhi iningi lalo liboshwe ibhande lamatshe eCambrian eligoqiwe. Lawa mabhande ayeshiselwe onqenqemeni lwesihlangu somhlaba esasikhona ngaphambili, ngaleyo ndlela andisa ubukhulu bezwekazi lokuqala abalakha. Imiphetho yesihlangu ithintwa amandla e-tectonic, nawo awabhubhise futhi awakhe kabusha, kanye ne-craton atholakala kuwo.
I-craton iyiyunithi enkulu yesakhiwo soqweqwe lomhlaba, eyakhiwe ngamatshe amaningi azinzile, ngokuvamile amatshe angenalutho kanye / noma ama-metamorphic. Kwesinye isikhathi imbozwe ngama-sediments amancane. I-craton evamile i-Canadian Shield (Precambrian). Amaphasela omhlaba abizwa ngokuthi "oceanic" noma "underwater cratons" angase angahlangabezani nale ncazelo. Igama elithi "Craton" empeleni liyigama elifanayo elithi isihlangu.
I-craton iyingxenye ezinzile yengaphakathi lezwekazi, ebonakala ngokuthi yakhiwe amatshe angaphansi acwebezelayo asendulo. Igama elithi craton lisetshenziswa ukuhlukanisa lezi zindawo nemisele ehambayo, okungamabhande alayini ezinsalela ezifakiwe. I-craton enkulu emaphakathi yezwekazi ingakhiwa izinto ezimbili: isihlangu somhlaba kanye nesiteji. Isihlangu siyingxenye ye-craton, lapho (ngokuvamile) amadwala angaphansi kwe-Precambrian abonakala kakhulu ebusweni. Ngokuphambene, endaweni yesikhulumi, izinga elingaphansi noma leleveli ephansi limbozwe inzika.
Ama-Cratons aseParaguay
I-craton iqukethe i-nucleus endala kakhulu. Uma kubhekwa isimo sawo esihambayo, ayahlangana akhe izwekazi. Nokho, aziveli ngaso sonke isikhathi ngaphandle. IParaguay inomfula i-Apa Craton (osuka enyakatho) kanye neTebicuary (eseningizimu). Ngezansi kweChaco kune «Pampia» Craton, okuyinto ihlukaniswe neRío de la Plata kanye neCraton de La Plata.
I-Transbrasiliano Lineamiento iyizoni ye-suture, yenyunyana, yokungqubuzana kwezwekazi lapho ama-cratons ehlangene khona, futhi inokuqhubeka kuze kube eNtshonalanga Afrika, idlula endaweni yaseBrazil. Lesi sakhiwo se-oda lokuqala, njenge-suture, sisuka ku-Lower Cambrian (iminyaka eyizigidi ezingu-528) ngenkathi i-Gondwana isungulwa.
Kukhona izingxabano uma i-craton yomfula i-Tebicuary ingeye-Río de la Plata noma cha, noma uma i-Paraná (ngezansi komgodi waseParaná) iyibhulokhi ehlukile kune-Río de la Plata. Nokho, imodeli eyamukelwa kabanzi inikezwa lapha.
Umehluko phakathi kwe-craton, ibheseni kanye nephutha
I-craton iyindawo ezinzile ye-continental crust futhi akazange ahlangabezane ne-orogenic tectonics eminingi noma amapuleti isikhathi eside. I-craton iqukethe isisekelo esicwebezelayo setshe le-Precambrian elivame ukubizwa ngokuthi isihlangu kanye neplatifomu lapho izinsalela ezivundlile noma eziseduze nezivundlile noma amatshe ayisihlakala azungeze isihlangu.
Izitsha ziyi-depressions ku-crust kwakhiwa umsebenzi we-plate tectonic, lapho kunqwabelana khona inhlabathi. Ukuphikelela kokubeka kuzoveza izinga elengeziwe lokugoba noma lokuncipha. Izitsha ze-Sedimentary, noma imicengezi ngamafuphi, zingaba njengomphongolo noma zinwetshwe kahle. Uma amatshe omthombo we-hydrocarbon acebile ehlanganiswa ngaphansi kwezimo zesikhathi esanele nokujula kokungcwatshwa, uwoyela negesi kungakhiqizwa endishini.
Okokugcina, iphutha a ukuphazamiseka noma indawo ye-laminar ekhona ku-brittle rock lapho kukhona ukugudluka okubonakalayo. Ngokuya ngesiqondiso esihlobene sokufuduka phakathi kwamadwala, noma ama-fault blocks, ezinhlangothini zombili zephutha, ukunyakaza kwabo kuchazwa njengokuqondile (noma okuvamile), ukuhlanekezela, noma ukuhamba kwezifundo.
Ngithemba ukuthi ngalolu lwazi ungafunda kabanzi mayelana ne-craton nezici zayo.