Binciken gawawwakin

A cikin ilimin ƙasa, fitarwa shine tsari wanda wani yanki na dutse da aka binne ya kusanci farfajiyar Duniya.

Ya bambanta da ra'ayoyin da suka danganci dutsen dutse da farfajiyar ƙasa saboda an auna shi a bayyane dangane da farfajiya ta Duniya, maimakon tare da ambaton wasu cikakkun bayanai, kamar geoid na Duniya.

Ya kamata a yi la'akari da fitar da duwatsu da aka binne a matsayin nau'o'i daban-daban guda biyu wato, fitar da gawa ta hanyar denudation / rushewa ko fitar da gawawwakin ta hanyar matakai na tectonic wanda ya biyo bayan rushewa. A cikin wannan yanayin, ana kawo duwatsu (ko kunshe-kunshe na dutse) daga matakan ɓarkewa masu zurfi (mita zuwa zurfin kilomita a ƙasa da farfajiyar Duniya) zuwa saman Duniya (watau matakan ɓargo mai zurfi) ta hanyar kauri (duba idan aka kwatanta da tasowa na tectonic) da / ko tectonics mai tsawo kuma daga baya ana fallasa su ta hanyar rushewa. Sau da yawa exhumation ya haɗa da ma'amala mai rikitarwa tsakanin kauri na ɓawon burodi, tectonics mai zurfi da rushewa. 

Musamman, akwai halaye masu yawa tsakanin hanyoyi daban-daban na binnewa da kuma rarrabewa kuma tsakanin su ya dogara da jerin sigogi kamar: 

* Rarraba sararin samaniya da na lokaci na ƙayyadadden nau'in
* Yankin metamorphic
* Rarraba sararin samaniya na shekarun sanyaya (duba misali radiometric dating na hornblende) 
* Rarraba sararin samaniya na hanyoyin matsa lamba-zazzabi-lokaci (P-T-t) hanyoyin matsa lamba-zafin jiki-lokaci (P-T-t) 

Cikakken ƙirar ƙasa, ilimin ƙasa na tsari, ilimin ƙasa da ilimin ƙasa na metamorphic sune mabuɗin fahimtar waɗannan matakai.

## Rashin amincewa
Ana iya la'akari da fitarwa ta hanyar denudation a matsayin tsari na fallasa kunshin dutse kawai ta hanyar cire abubuwan da ba a haɗa su ba ko kuma tsaunuka masu ƙarfi. Denudation an dauke shi a matsayin tsari wanda ke cire sassan saman duniya ta hanyar matakai na zahiri da ke faruwa ta halitta (misali kankara, iska, ruwa, rushewar ƙasa). Ta hanyar wannan nau'in tonowa, wani abu da aka binne a baya a cikin turɓaya, misali, an gano shi kuma ana iya fallasa shi.

## Binciken gawa ta hanyar tsarin tectonic
Exhumation ta hanyar matakai na tectonic yana nufin duk wani tsarin ilimin ƙasa wanda ke kawo duwatsu daga matakan ɓawon burodi masu zurfi zuwa matakan ɓawon rufi masu zurfi. Duk da yake rushewa ko denudation yana da mahimmanci wajen fallasa waɗannan duwatsu masu zurfi a farfajiyar Duniya, abin da ke haifar da duwatsu zuwa ƙananan ɓawon burodi har yanzu ana ɗaukar su hanyoyin fitarwa. Binciken geological yana faruwa a kan ma'auni daban-daban, daga ƙananan ma'aunin da ke faruwa a cikin ɓawon burodi mai zurfi (kasa da zurfin kilomita 10)  wanda ke haifar da fitarwa a cikin tsari na centimeters zuwa ma'aunonin mita, zuwa manyan siffofi da suka samo asali a matakan ɓawon burbushin da suka fi zurfi wanda, fitarwa yana cikin tsari na daruruwan mita zuwa kilomita. 

Hanyoyin ilimin ƙasa waɗanda ke fitar da zurfin ɓarkewar ɓarkewa na iya faruwa a cikin saitunan tectonic daban-daban amma a ƙarshe ana fitar da su ta hanyar haɗuwa da faranti na tectonic ta hanyar subduction. Dangane da nau'in iyakar haɗuwa, fitarwa yana faruwa ta hanyar turawa a cikin ƙuƙwalwar ƙuƙwalwa, ta hanyar obduction da / ko a matsayin tsari a lokacin sake zagayowar orogenic (watau ginin dutse da sake zagayowarsa).

### Ƙarfafawa
A lokacin subduction na farantin teku a ƙarƙashin ɓawon burodi na nahiyar, wasu raguwa na ɓawon burodin teku za a iya kama su sama da ɓawon burin nahiyar ta hanyar obduction. Ana kiran duwatsun da aka samo a kan ɓawon burodi na nahiyar Ophiolite .  Duk da yake ainihin hanyar da ke bayan kafa ophiolites har yanzu tana cikin muhawara,  waɗancan duwatsu har yanzu suna nuna misali na duwatsu da ake fitarwa da kuma fallasa su a farfajiya ta hanyar tsarin tectonic na obduction sannan kuma fallasa. 

### Binciken zurfin ɓawon burodi a lokacin sake zagayowar orogenic.
Fitar da duwatsu masu zurfi a lokacin sake zagayowar orogenic yana faruwa galibi a lokacin haɗari na nahiyar ko kuma a lokacin tsawo bayan haɗari  kuma saboda haka, an haɗa shi cikin hanyoyin guda uku waɗanda ake amfani da su don bayyana binnewa da fitar da sake zagayolar wato, syn-convergent orogenic wedges,   tashar tashar gudana (wanda aka fi sani da ductile extrusion)  da kuma bayan haɗuwa. 

#### Syn-convergent orogenic wedge
A lokacin subduction zuwa matakai na haɗari na sake zagayowar orogenic, wani tectonic wedge siffofi a kan prowedge (gefen subducting farantin) kuma yawanci retrowedge (yanayin nahiyar) na orogen. A lokacin ci gaba da haɗuwa, ƙuƙwalwar tana riƙe da siffarta ta hanyar kula da kusurwarta mai mahimmanci na taper  ta hanyar hulɗar kauri ta hanyar ƙaruwa ta hanyar ƙuƙwalwa ko yaduwar ƙasa (ƙuƙwalwa ta gaba) da ƙanƙanta ta hanyar kuskuren al'ada da rushewa a saman ɓangaren ƙuƙarar. Rushewar wedge yana da tasiri sosai ga ƙarfin da ke cikin wedge, wanda ke inganta fitarwa ta hanyar tura duwatsu na tsakiya zuwa bangon rataye na wedge. Halayen wannan yanayin na exhumation sun haɗa da, shaidar da ke da ƙarfi ba tare da juyawa ba, metamorphism mai zurfi, shekarun sanyaya suna ci gaba da ƙuruciya zuwa matakan tsari masu zurfi kuma cewa exhumation a matakan tsari mafi girma yana da alaƙa da binne matakan tsari. Tectonics na wannan nau'in yana haifar da ninkawa da belin turawa ko kuma idan an gina su a tsawon lokaci, na iya samar da ma'adanai masu zafi, kamar Himalayas. 

#### Gudun tashar
Gudun tashar yawanci yana faruwa a cikin orogens mai zafi lokacin da orogen ya isa ya inganta narkewa a cikin ɓangaren tsakiya-ƙasa na orogen zuwa wani batu inda duwatsu suka kai ƙarancin viscosity wanda ke ba su damar gudana. Daga baya waɗannan duwatsu na iya rarraba daga tushe kuma su fara gudana zuwa matakan ƙuƙwalwa mafi girma tare da gradients na matsin lamba wanda zai iya haifar da narkewar ruwa ko bambance-bambance a cikin yanayin ƙasa da bambance-mbance na gefe. Dukansu biyu suna shafar lalacewa. Halaye na wannan yanayin fitarwa sun haɗa da shearing na al'ada a lokaci guda da kuma juyawa shearing tare da rufin da tushe na tashar bi da bi, high-temperature retrograde metamorphic assemblages, cooing shekaru ya kamata su zama matasa zuwa gaban tashar da P-T-t hanyoyin da ke ba da shawarar tsawo binnewa da synchronous exhumation a ko'ina cikin tashar.

#### Rushewar nauyi bayan jujjuyawar
Rushewar nauyi na bayan haɗuwa (tsawo) yana faruwa da zarar dakarun haɗuwa ba za su iya tallafawa ƙarfin nauyi na orogen da aka gina a lokacin haɗari ba. [ana buƙatar hujja] A lokacin rushewa, ana fitar da duwatsu masu girma daga ainihin orogen ta hanyar gudana sama zuwa yankunan da aka ƙuntata yanzu suna samar da ƙwayoyin ƙwayoyin cuta masu kama da ƙwayoyi. A madadin haka, ko kuma tare da fadada tsakiyar orogen, yaduwar dutse zuwa gefen na iya haifar da fitarwa tare da jerin ƙuƙwalwa ko ƙuƙwalwar ƙuƙwasawa da kuskuren al'ada  kuma a ƙarshe samar da nau'in ƙuƙura da ƙuƙusa tare da gefen orogen da ya rushe. Halaye na rushewar nauyi sun haɗa da gefen waje, yankuna masu ma'ana na al'ada tare da gefen mahimman abubuwa da hanyoyin P-T-t kawai.

## Manazarta