102

"Prekambrij"PROTEROZOIK

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Proterozoik

• proterozoik– 2,5 mrd. do ~ 542

mil. god.

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Proterozoik

• donji (paleoproterozoik): 2,5 - 1,6 mrd. god.

• srednji (mezoproterozoik): 1,6 - 1,0 mrd. god.

• gornji (neoproterozoik): 1,0 - 542 mil. god.

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103

Proterozojska orogeneza

• formiranje velikih kratona

• orogeneza• orogen: svako

stijensko tijelo deformirano orogenezom

Wopmay orogen

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Proterozojska orogeneza

• debeli talozi kvarcnih pješčenjaka

• karbonatna platforma• prijelazne muljevite

stijene• taloženje fliša• turbiditi, a zatim

pukotine isušivanja i stromatoliti

• taloženje molase

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Proterozojska orogeneza

• karbonatnaplatforma– ciklično

taloženje indiciralo progradaciju plimskih ravnica preko lagune

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104

Proterozojski događaji

• široke glacijacije

• stromatoliti

• rani eukarioti

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Razvoj eukariota

• razvoj prokariotnih stanica: – mitohondrijski– kloroplast

• iz prokariota nastali protisti

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Alge

• višestaničniprotisti

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105

Alge

• prokariotneforme

• akritarki

• povećanje sadržaja kisika

a) fosilne prokariotne stanice Gunflint formacije

b) akritark Dicyotidiumc) akritark drugačije forme

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Proterozojski život

• fosilni trgovi– pojavili se prije

570 mil. god.

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Proterozojski život

• dokazi djelovanja organizama

• tendencija povećanja složenosti i varijacija

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106

Proterozojski život

• fosili bez skeleta– slični žarnjacima

• Ediacara fauna

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Proterozojski život

• mogući fosili člankonožaca

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Proterozojski život

• skeletalni fosili

• spikule spužvi

Cloudina

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107

Proterozojski kontinenti

• kontinentalna akrecija

– mikroploče prirasle kontinentu zbog subdukcije

– orogenska stabilizacija

– remobilizacija

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Proterozojski kontinentiOrogenska stabilizacijaa) akumulacija sedimenata,

subdukcijab) felsička kora kontinentac) subdukcija oceanske

kore pod kontinentalnu, stabilizacija sedimenata kontinentalnog ruba (metamorfizam), dodavanje magmatskih stijena kontinentalnom rubu

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Proterozojski kontinenti

• Baltički štit– transgresija na Jatulijsko kopno i

taloženje Jatulijskih naslaga– Švedska - metamorfozirani magmatiti i

sedimentne stijene (Leptit-formacija)– svekokarelidsko izdizanje 1,9-1,8 mrd.

god.

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108

Proterozojski kontinenti

• dezintegracija, diferencirano kretanje blokova, intruzije dijabaza, granita i vulkanizam - taloženje jotničkih naslaga

• konac proterozoika: izdizanje • čini cjelinu s Ukrajinskim štitom i Ruskom

pločom - Fenosarmacija

• Hebridi - Škotska• toridonski pješčenjak

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Proterozojski kontinenti

• Srpsko-makedonska masa i Rodopi:– donji dio: metamorfiti amfibolitnog

facijesa• gnajs, tinjčasti škriljavci, kvarciti, mramor

– gornji dio: metamorfiti facijesa zelenih škriljavaca

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Proterozojski kontinenti

Finska. Kompletni ofioliti 1,96 mrd. god. Dokaz konvergentnog ruba.

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Proterozojski kontinenti• Kanadski štit

• Laurencija se ubrzano širi

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Proterozojski kontinenti

• 1,95 - 1,85 mrd. god.– izgradnja

Laurencije od 5 mikrokontinenata

• 1,9 - 1,8 mrd. god.– odvajanje Superior

provincije • 1,8 - 1,6 mrd. god.

– prirast kontinenta prema JZ 800 km

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Proterozojski kontinenti

• abortirani rift 1,2 - 1,0 mrd. god.

• Grenville orogeneza 1,1mrd. god.– završni stadij

proterozojske kontinentalne akrecije Laurencije

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110

Proterozojski kontinenti

Srednjekontinentalni rift.

Konglomerati aluvijalne lepeze.

Vulkaniti.

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Proterozojski kontinenti

• Keweenawan bazalti– ruda bakra

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Proterozojski kontinenti

Srednje i gornjeproterozojska sedimentacija na zapadnoj obali Sj. Amerike.

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Proterozojski kontinenti

• Afrika– unutar kratona rovovi i bazeni– orogeneza 1,2-0,9 mrd. god.

• boranje naslaga Witwatersrand i Transvaal– panafrička (katanska) orogeneza 800-

550 mil. – stara kratonizacija + mlađe

intrakratonske orogeneze = formiranje prostrane "afričke" ploče

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Proterozojski kontinenti• u Sibiru - Angara• veliki kontinent: Indija, Arabija, veći dio Afrike i J.

Amerike, Australija, Antarktika - kasnije Gondvana

• prekambrijske orogeneze:• kenorijska (neoarhaik) - Kanadski štit• eburnijska (sr. paleoproteroziok) - Afrika• Wopmay (sr. paleoproterozoik) - Kanadski štit• hadsonijska (kasni paleoproterozoik) - Kanadski štit• Grenville (mezoproterozoik) - Kanadski štit• bajkalska (neoproterozoik) - Angara (Sibirija)• panafrička (neoproterozoik) - Afrika

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Proterozojski kontinenti

• Rodinija– superkontinent

izgrađen od kontinenata

– dezintegracija Rodinije prije 0,8 - 0,7 mrd. god.

a) Rodinija prije 1 mrd.. b) Drugi superkontinent?

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Proterozojski kontinenti

• Supergrupa pojasa - Kanada– 1,5 - 0,9 mrd. god.

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Formacije vrpčastog željeza

• završetak razvoja prije 1,9 mrd. god.– rožnjak

kontaminiran željezom - crvena ili smeđa boja

– proslojavanje s plavičastim slojevima bogatim željezom (magnetit)

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Crveni slojevi

• nisu nađeni u stijenama starijima od 2 mrd.

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Zemlja kao gruda snijega

• oledbe u gornjem proterozoiku – neoproterozojski

glacijalni sedimenti

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Zemlja kao gruda snijega

• Sturtian oledba - prije 700 mil. god.• Marinoan oledba - prije 600 mil. god.

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Zemlja kao gruda snijega

Tilit, dropstoni i karbonatne stijene.

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Zemlja kao gruda snijega

• dokaz za Marinoan ledeno doba u Maroku

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Proterozoik

• Mineralne sirovine• željezo: SAD, Kanada• nikal: Kanada• platina, krom: J. Afrika• nafta i plin: Sibir i Kina• pegmatitne žice: razni minerali

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Stromatolitiobilniji

Jednostavniakritarki

Višestaničnealge

Rodinijaprije 1 mrd.

Kad je prije 2 mrd.god. atmosfera doseg la umjerenu količinu kisika, formacije vrpčastog željeza završile razvoj.

Rast kontinenata

Maksimalni razvoj stromatolita

Prokario ti dominantni

Novi superkontinent(550 mil.) nakonloma Rodinije?Složen iji

akritarki

Eksplozivna radijacija životinja

Pri koncu protero-zoika rif tanje for-miralo glavne kon-tinente u paleozoiku

Brze k limatskepromjene -Zemljaprekrivena ledom.

Najstariji fo-sili životinja.

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