id	keyword
gc-18	stromatolites
gc-18	fi g.
gc-18	crust
gc-18	grotzinger
gc-18	sparry
gc-18	microbial
gc-18	carbonate
gc-18	hybrid
gc-18	precambrian
gc-18	layers
gc-18	sumner
gc-18	james
gc-18	proterozoic
gc-18	riding
gc-18	sparry crust
gc-18	laminae
gc-18	abiogenic
gc-18	fabrics
gc-18	calcite
gc-18	knoll
gc-18	deposits
gc-18	formation
gc-18	mats
gc-18	et al
gc-18	grains
gc-18	examples
gc-18	precipitation
gc-18	crust stromatolites
gc-18	sediment
gc-18	dark
gc-18	geologia
gc-18	cement
gc-18	oor
gc-18	components
gc-18	marine
gc-18	late
gc-18	day
gc-18	seafl
gc-18	canada
gc-18	group