10/11: Selected Carbonate Depositional Settings & Facies and Walther's Law

carbonate platforms and sabkha, lithofacies

what are the types of carbonate platforms?

ramp, non-rimmed shelf, rimmed shelf, epieric, isolated

what is the definition of a carbonate platform?

a place where carbonate can develop

what is an epieric platform?

one that is the length of an entire continent (not common presently)

what is an isolated platform?

a topographic high in the sea

what are some things that can be present on a carbonate platform?

tidal flat, shelf lagoon, rim, shelf margin reef, skeletal sand, ooid bank (shoal), patch reefs

where do oolite, pellet mud, and mud form? example? why?

in protected areas, like behind the island, current has a tough time getting there, like a swimming pool

what is a sabkha environment?

a coastal, supratidal mudflat or sandflat where evaporite saline minerals accumulate due to the arid climate

why are sabkhas so saline?

its warm and dry, lots of evaporation but also because its a narrow body of water, currents have a tough time coming through

describe the sections of sabkha (low to high)

lower intetidal is lagoonal muddy and peloidal sands, middle intertidal is microbial mats and gypsum, upper intertidal is microbial mats and gypsum, bedded unit is nodular anhydrite replacement from gypsum, top is laminated and neterolithic anhydrite in eolian sand

what is a lithofacies?

the texture, mineralogy, grain size, and the depositional environment that produced a rock

explain high energy as a process?

sorts well and reworks sediment

what is lateral accretion? explain?

the sideways movement of meander bars, larger grains are close the higher velocity side, fining upslope

what type of facies succession will you see if you cut a cross section beside an existing river?

fining upwards

what is important about walther’s law?

only facies and facies areas that can be observed beside each other in the present can be superimposed without the need for a major break

what is walther’s law?

facies occurring in a conformable succession above one another were formed in laterally adjacent environments