Cov pob zeb uas tsim rau ntawm pob zeb gneiss yog vim muaj ntau lub pob zeb uas yog ib feem ntawm nws cov khoom tsim. Kev siv lo lus gneiss hnub rov qab mus rau nruab nrab-1700s Nws pob zeb uas tshwm sim los ntawm cov pob zeb sedimentary hu ua paragneiss thiab cov pob zeb uas tsis muaj zog hu ua orthogneiss.
Gneissic banding yog dab tsi?
Gneiss yog ib lub pob zeb metamorphic tus yam ntxwv by banding tshwm sim los ntawm kev sib cais ntawm ntau hom pob zeb, feem ntau lub teeb thiab tsaus silicates. Tsis yog ib qho kev qhia tshwj xeeb ntawm cov pob zeb hauv av, lub sij hawm yog qhov qhia txog kev ntxhib los mos. Cov "gneissic texture" yog hais txog kev sib cais ntawm lub teeb thiab tsaus ntxhia.
Banding hauv gneiss daim ntawv li cas?
- Cov banding hauv gneiss tuaj yeem tsim los ntawm thawj txheej txheej hauv cov protolith, lossis nws cov shear ntawm qhov kub siab- metasomatism: hloov hauv tshuaj muaj pes tsawg leeg los ntawm hydrothermal kua; cov kua dej no tshem tawm lossis nqa cov khoom. Foliated pob zeb muaj cov txheej txheem sib npaug ntawm cov pob zeb tiaj tus thiab elongated minerals.
Gneiss keeb kwm yog dab tsi?
Gneiss yog qib siab metamorphic pob zeb, txhais tau hais tias nws tau raug kub thiab siab dua li schist. Nws yog tsim los ntawm metamorphosis ntawm granite, los yog sedimentary pob zeb. … Gneisses los ntawm western Greenland suav nrog cov pob zeb qub tshaj plaws uas paub (ntau dua 3.5 billion xyoo).
Dab tsi ua rau pob zeb hauv pob zeb?
Flow banding yog tshwm sim los ntawm kev sib txhuam ntawm cov nplaum magma uas nyob rau hauv kev sib cuag nrog cov pob zeb sib cuam tshuam, feem ntau cov pob zeb ntawm phab ntsa mus rau qhov chaw nkag los yog, yog tias cov magma tawg., qhov chaw ntawm lub ntiaj teb hla lub lava ntws.
