ENVIRSC 2E03 Lecture Notes - Lecture 3: Micrite, Dunham Classification, Ooid
16 Oct 2018
School
Department
Course
Professor
Document Summary
Araonite caco3 (orthorhombic): unstable at surface, make up coral reefs\ Dolomite camg(co3)2 : magnesium causes rocks to be a darker brown when comparing. Carbonate sediments are created through biological growth and not made like their clastic counterparts through weather of parent rock material. Chemical sedimentary rocks composed of more than 50% carbonate minerals: Tufa : porous carbonate deposited around hot springs. Travertine : banded calcitic rock formed in caves. Limestones are mostly composed of skeletal fragments of caco3 secreting organisms. There are also chemical precipitates, but they are less important. Most carbonate production occurs in shallow, warm waters. Modern growth window for coral reefs is very narrow- they need warm, clear, agitated water with plenty of sunlight. This would have likely been the same in the geological past. Reefs grow in consistent temperature water and surroundings. Most reefs are found inbetween the tropic or cancer and tropic of capricorn.
