Ch4_sequences, Sea Level Changes, And Transgression- Regressions

8/9/2019 Ch4_sequences, Sea Level Changes, And Transgression- Regressions

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SEDIMENTARY SEQUENCES, SEA LEVEL CHANGESAND TRANSGRESSION REGRESSIONS

A depositional eni!on"ent is a #eo"o!p$i% &nit is %$a!a%te!i'ed () a

&ni*&e set o+ p$)si%al, (iolo#i%al, %$e"i%al p!o%esses to p!od&%e a

%$a!a%te!isti% deposit

Identi+i%ation o+ depositional eni!on"ent in an%ient sedi"ent !e%o!d

is identi+i%ation o+ palaeo-#eo"o!p$i% &nit

In +a%ies anal)sis ."ostl) lit$o+a%ies/ #!ain si'e and (eddin#

st!&%t&!es a!e e"p$asi'ed T$e +a%ies a!e #!o&ped into +a%ies

asso%iations

0a%ies "odels .s&""a!) o+ depositional eni!on"ents and its

p!od&%t/ a!e e!) &se+&l


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T$e e!ti%al se*&en%es a!e (&ilt +ollo1in# t$e 2alt$e!3s La1 o+

0a%ies, onl) t$ose eni!on"ents t$at a!e late!all) asso%iated

to ea%$ ot$e! #eo#!ap$i%all) "a) (e%o"e asso%iated in a

e!ti%al se*&en%e

In t$e st&d) o+ p!esent da) eni!on"ents dist!i(&tion o+

lit$o+a%ies in $o!i'ontal se*&en%e is dete!"ined and a

$)pot$eti%al e!ti%al se*&en%e is p!oposed


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Walthers law of facies is valid in vertical packageswithout any erosional surfaces. The erosional surfaces

in a stratigraphic succession usually separate

sediments of different depositional domains.


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In s$allo1 "a!ine deposits, t$e e!ti%al se*&en%es a!e

p!od&%ed in !esponse to t$e t!ans#!ession and !e#!ession

T!ans#!ession is a p!o%ess o+ "i#!ation o+ t$e s$o!eline o+

t$e sea in a land1a!d di!e%tion It is &s&all) !elated to !isin#

!elatie sea leel Ho1ee!, d&!in# e4%ess e!osion

t!ans#!ession "a) o%%&! d&!in# +allin# !elatie sea leel

Re#!ession is "i#!ation o+ s$o!eline o+ t$e sea in t$e

sea1a!d di!e%tion It is &s&all) !elated to +allin# !elatie sealeel Ho1ee!, d&!in# e4%ess net deposition !e#!ession "a)

o%%&! d&!in# !isin# !elatie sea leel


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D&!in# !apid +allin# sea leel 1it$ little sedi"ent s&ppl),

ne#li#i(le deposition ta5es pla%e Rapid !isin# sea leel is

e!osional and al"ost no deposition ta5es pla%e

In a sedi"enta!) s&%%ession, one identi+ies lit$o+a%ies

se*&en%es s$allo1in# &p1a!d .6!o#!adin#/, o! deepenin#

&p1a!d .Ret!o#!adin#/

In an%ient sedi"enta!) deposits "ost o+ t$e se*&en%es a!e

p!o#!adin# se*&en%es +o!"ed &nde! slo1l) !isin# sea leel and

$i#$ sedi"ent s&ppl)


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0!a'ie! dis%&sses t$at a st!ati#!ap$i% s&%%ession is "ade &p o+

Depositional Events, 1$i%$ a!e +a%ies se*&en%es %o"posed o+

p!o#!adation, a##!adation and t!ans#!ession

See!al Depositional Events%onstit&te a Depositional Episode,

1$i%$ is te!"inated () a "a7o! t!ans#!ession

8&ildin# (lo%5s o+ se*&en%e st!ati#!ap$) .S)ste" T!a%ts/ a!e

pa!ase*&en%es A pa!ase*&en%e is &s&all) a p!o#!adin#

se*&en%e (o&nded () +loodin# s&!+a%es o+ t!ans#!essions


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Se*&en%e st!ati#!ap$) #ene!all) $elps in &nde!standin#

t$e s&%%ession in te!"s o+ sea leel %$an#es 1$i%$ also

a++e%t t$e sedi"ent s&ppl) and a%%o""odation spa%e

Depositional se*&en%e is "ade &p o+ s)ste" t!a%ts

na"el) Lo1stand S)ste"s T!a%t, T!ans#!essie S)ste"

T!a%t, Hi#$ Stand S)ste"s T!a%t and S$el+ Ma!#inS)ste" T!a%t


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T$e pa!ase*&en%e o! +a%ies se*&en%e is %o"posed o++ollo1in# +a%ies

Li#nite sedi"ents

Ca!(ona%eo&s s$ale

G!e) s$ale

S$ell %a!(onate

It "a5es a s$allo1in# &p1a!d p!o#!adational se*&en%e


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The building blocks of system tract are parasequences or

simple sequences. A parasequence is composed of a

succession of genetically related facies bounded by flooding

surfaces.

Generally several parasequences are stacked vertically to

produce a system tract.


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Ch4_sequences, Sea Level Changes, And Transgression- Regressions

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