Page 40 - Carbonate Facies in Geologic History

Discussion of Idealized Pattern 27

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. ...... ~ ~ ..... # v J . • ~~-z-~ :::s:::: z
--k U"lty IfIC,.. .... ~
)7.4$ ". : >t.S ...
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S 6 7 9
Orgarnc (~CoJoql(,) "~r/ Sand on edg' <f plarform O!!,n plarform (normal Rr5trr("ud plalfornu Pial/or," rHllwrllrs
a) Bound$lonc m 0) Shoal hme sand manne. hmned (Iluna, iii) Blocluuc waClCSIOnc. a) Nodular anhydn.e
b} eru ton accumulal1 n bl I land "'"h dune nds a) L,me and bodoe I.goon nd b y nd dolomlle on
or orBun!\: dcbr~ and b} Wackestone-mud tone b) LI.h.,.b,oeJasllC sands ,all n ...
lime mud . blndstonc area bioherms In udal cha.nnels b) Lammated evaponlc
cl Bam lone c) Areas dcl II c) Lime mud-tide flats 10 ponds
d) Fme dll5l1c Units
M I\-C limestone- Caicarenlllc·oolluc lime V toable rbonales and Generally dolomtlc and Irrcsularly hlmmaled
dolomllr sand rdolomlle d. II dolomllic hmeslone dolomut and anh),drlte.
may grade 10 red bed
Llghl Llghl Dark lohgbl Llghl Red. )ello"'. brown
Soundstones lind packcls Gr~mslones OAtil Orled. Great ",ariel), of textures. Cloned. pclleled mudSlone
of !ram tone. pa. kS:lone rounded g.raJn tone to mudstone and gralMtone; laminated
mudslone. coanc htho-
d lie waclcstone In
channels
Mass"I\c orgamc Slruc:ture \<ted,um 10 large seale BurrOWing Iraces \lay Bmiscye.51romalolllcs.. Anhydrlle .fler g~",um.
or open rrameworl \\nh or beddIng; promlOent mm lamm lion. graded nodular. roselle'S.,
roofed cavities. festoons common beddmg. dolomne crusts chlc~enwlre. and bl.des;
Lamlnallon contrary on n I r -bedded Irregular lamlnallon.
IOlr'.JnIY ~nd m channels eorbonale eohehe
None Only some qu.m sand QUiles Ilnd carbonates OiilSI1CS iilnd carbonates W,ndblown. land derl\Od
iildmu:cd In well segregOled bed In well segregated beds lIdmlJuures; da tla. may
be Imporlanl units
'bJor rrame building Worn and Ilbralded cO- Open m3nne f3una Very limited (auna.. mainly Almost no indigenous
colome 'Wuh ramose qumas of forms h\llng at 13 kmg (e g. echmoderms. gastropods, algae. ctrtam fauna. eJ:tePI (or
rorm In pod:eLS. In Ilu or on slopc~ few cephal pod brachiOpod ); fOf3.mlnlrUII. (e. g. mllio- stromalohlle algac
communltle§ dwdhng. 10 md! cnous orgam m mollusca. sponges. roram hds) and "","cod
«MaiO nKhes .Igae abund nl; J>3lch
reef presenl
Fig. 11-4 (continued)
Discussion of Idealized Pattern

The pattern of Fig. 11-4 results from a combination of effects of slope, geologic
age, water energy, and climate, and as these vary, so will the patterns they control.
Also, any ingress of terrigenous clastics will affect it. It is therefore obvious that no
one example should include all nine facies belts. Clearly, for example, whether
belt 1 or 2 occurs is dependent on whether the constructed carbonate bank or
ramp rises from a deeper water euxinic basin or whether it rises above a shelf sea
with open circulation. Similarly, occurrences of belts 3 and 4 are determined by
the steepness of the slope, the depth of water into which it plunges, and the
amount of wave energy at its upper margin. The organic reef (belt 5) may alternate
along facies strike with lime sand (belt 6), or both may be present, dependent on
the combinations of geologic age and water energy. If a deep enough lagoon exists
behind the barrier belts in a constantly temperate or tropical climate, it may have