Using  the  Book  Cliffs,  Utah  as  a  Case  Study  to  Teach  Concepts  of  Sedimentology  and  Stra<graphy  

William  W.  Li@le  

Purpose  

The  purpose  of  using  a  semester-­‐long  case  study  to  teach  principles  and  concepts  of  sedimentary  geology  is  to  present  material  in  a  manner  that  shows  rela<onships,  rather  than  disjointed  pieces  of  informa<on,  fostering  an  environment  of  understanding,  rather  than  just  memoriza<on.    If  concepts  are  understood,  there  is  li@le  to  memorize;  it  just  makes  sense  and  becomes  obvious.  

Objec<ves  

1)  Understand  rela<onships  between  physical  features  (e.g.  sedimentary  textures  and  structures)  and  the  processes  (e.g.  medium,  energy)  that  form  them.  

2)  Understand  the  concepts  of  facies  and  facies  associa<ons  and  how  they  correspond  to  deposi<onal  environments,  systems,  and  systems  tracts.  

3)  Understand  rela<onships  between  space  produc<on  and  filling.  

4)  Understand  the  concept  of  base  level  and  how  it  influences  deposi<onal  successions.  

Methods  

Use  tradi<onal,  well-­‐established  types  of  exercises  (and  some  new),  but  <e  each  to  a  specific  region  and  stra<graphic  interval,  in  this  case,  the  Book  Cliffs,  UT:    1)  Rock  classifica<on  &  iden<fica<on  of  sedimentary  structures  (Use  hand  samples  together  

with  outcrop  photographs)    2)  Measured  sec<ons  (Constructed  from  outcrop  data)  

3)  Regional  cross  sec<ons  (from  outcrop  data)  

4)  Litho-­‐,  chrono-­‐,  allo-­‐,  and  sequence  stra<graphic  surfaces  and  components.  

Why  the  Book  Cliffs?  Con<nuous,  well-­‐exposed,  dip-­‐  and  strike-­‐oriented  outcrops  

Abundant  Resources  

It’s  the  global  standard  

Introductory  Ques<ons  

•  What  do  you  see?  (interbedded  sandstone  and  mudstone)  •  What  formed  the  bedding?  (changes  in  energy  condi<ons)  •  Why  are  energy  condi<ons  different?  (water  depth)  •  Are  there  any  ver<cal  trends  in  the  bedding?  (sand/mud  ra<o)  •  What  is  responsible  for  the  ver<cal  trend?  (base  level  change)  •  What  causes  base-­‐level  change  (eustasy  and  tectonics)  •  Does  this  succession  reflect  base  level  rise  or  fall?  (mostly  rise)  •  Does  this  succession  reflect  shoreline  transgression  or  regression?  

(regression)  •  What  else  might  impact  the  pa@ern?  (sedimenta<on  rate)  

Sedimentary  Rocks  and  Structures  

Rather  than  random  samples  with  no  context,  chosen  simply  because  they  are  “good,”  those  I  use  come  from  the  three  areas  we  work  during  field  camp,  one  of  which  is  the  Book  Cliffs.    Each  sample  is  accompanied  by  a  photograph  to  show  field  rela<onships.    Benefits:    

•  It  is  not  just  a  rock.    It  came  from  somewhere  and  is  related  to  other  rocks.  •  The  sample  is  part  of  a  larger  body.  •  The  rocks  form  ver<cal  pa@erns.  

Disclaimer:  Some  <mes,  I  “cheat”  a  li@le.    This  photo  is  from  a  world-­‐class  site  visited  by  hundreds  of  geologists  each  year.    I  would  not  collect  from  here.    However,  because  I  want  to  use  this  site  as  part  of  my  case  study,  I  subs<tute  a  sample  I  collected  from  a  similar  outcrop.  

I  reuse  the  same  photos  repeatedly  through  the  course  to  foster  familiarity.  

Facies  &  Facies  Associa<ons  

Enge,  H.D.  et  al.  (2010)  

River-­‐dominated  Delta  Wave-­‐dominated  Delta  

The  study  of  sedimentology  and  stra<graphy  is  a  study  of  pa@erns.    Understanding  pa@erns  can  lead  to  the  recogni<on  of  specific  deposi<onal  environments  and  systems.    For  example,  from  a  distance,  these  two  deposits  look  very  much  alike;  however,  closer  inspec<on  reveals  significant  differences.  

The significance of surfaces that represent breaks between episodic depositional events can be shown at virtually any scale from bed and bedset to members and formations..

Bedding  Planes  &  Other  Surfaces  

Facies  Models  

Examples  of  virtually  every  significant  clas<c  deposi<onal  system  are  found  in  the  Book  Cliffs,  again,  placing  them  into  context  by  showing  field  rela<ons.    Instead  of  just  sta<ng  that  braided  streams  transi<on  down  stream  into  meandering  then  deltas,  it  can  be  shown  to  be  happening.  

Braided  fluvial   Meandering  fluvial   Anastomosed  fluvial  

Prograding  shoreface   Barrier  island   Distributary  channel  

Delta  front   Deep-­‐water  fan   Deep-­‐water  shelf  

Lithostra<graphy  

Howard  (1966)  

Concepts  of  lithostra<graphy,  including  defini<on  based  on  physical  characteris<cs  and  stra<graphic  posi<on  are  easily  seen  in  the  Book  Cliffs.    Addi<onally,  nearly  all  of  the  units  have  locally-­‐derived  names,  demonstra<ng  the  significance  of  unit  names  and  importance  of  type  areas  and  sec<ons.  

Regional  Correla<on  Price  River  Forma<on  

Spanish  Fork  Canyon   Price  Canyon   Thompson  Canyon  

Stra<graphic  units  have  been  correlated  using  lithostra<graphy,  allostra<graphy,  biostra<graphy,  chronostra<graphy,  and  sequence  stra<graphy.    Each  can  be  found  in  published  reports.  

Lateral  Facies  Changes  (systems  tracts)  Price  River  Forma<on  

Spanish  Fork  Canyon   Price  Canyon   Thompson  Canyon  

Because  of  the  con<nuity  of  outcrops,  stra<graphic  units  can  be  traced  laterally  to  observe  coeval  sedimentary  deposits  from  different  environments  and  systems.  

Panther  Tongue,  Star  Point  Sandstone  

Gen<le  Wash   Spring  Canyon  

Concepts  of  Base  Level,  Accommoda<on,  Sedimenta<on  Rates,  and  Cyclicity  in  

Deposi<onal  Pa@erns  Coastal  Example  

Marine  Example  

Couplets  represent  alterna<ng  episodes  of  higher  sea  level  (limestones)  and  lower  sea  level.  

Fluvial  Example  

Fluvial  style  and  rela<ve  abundances  of  channel  vs.  overbank  deposits  reflect  rates  of  space  produc<on  vs.  filling  and  are  <ed  to  fluctua<on  in  base  level.  

Shoreface  Deposits  

Fluvial  Deposits  

Shoreface  Deposits   Offshore  to  shoreface  shallowing-­‐upward  succession   Shoreface  

Fluvial  

Fluvial  Deposits  

Offshore  Shoreface  

Shallowing-­‐upward  succession  

Shallowing-­‐upward  succession  

Sequence  Stra<graphy  

FSST  

LST  

TST   HST  

Sequence  Boundary  (SB)  

Transgressive  Surface  (TS)  

Maximum  Flooding  Surface  (MFS)  

The  SB  and  TS  merge  at  the  point  of  maximum  base  level  rise.  

The  TS  and  MFS  merge  from  the  proximal  end  of  the  TST  to  the  proximal  end  of  the  LST.  

The  TS  and  MFS  merge  at  the  distal  end  of  the  TST.  

All  three  surfaces  merge  at  the  toe  of  the  FSST.  

SB  

HST  (late)  

HST  

HST  (early)  TST  

LST  MFS   TS  

Shoreface  Fluvial  

Fluvial  Deposits  

Offshore  Shoreface  

Shallowing-­‐upward  succession  

Shallowing-­‐upward  succession  

More distal facies

More proximal facies

Flooding  Surfaces  

More distal facies

More proximal facies

Sequence  Boundaries   Parasequences  

Sha

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upw

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Sha

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up

war

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Flooding Surface

Flooding Surface

Flooding Surface

Parasequence  Stacking  Pa@erns  

Book  Cliffs  Exercise  1-­‐1:  A)  On  the  right  side  of  the  photo  (N),  mark  lithostra<graphic  contacts  and  label  units.  B)  On  the  lei  side  of  the  photo  (S),  mark  sequence  stra<graphic  surfaces  and  label  systems  

tracts.  C)  To  the  right  of  each  sequence  stra<graphic  element  label,  indicate  its  significance  to  base  

level  change  and  parasequence  stacking  pa@ern  (i.e.  fall,  rapid  rise,  slowing  rise,  retrograda<on,  aggrada<on,  prograda<on).  

Exercises  -­‐  Photo  Analyses  

Kmb  

Ksp  

Kss  

Kbs  

Kba  Kbk  

SB  Fsst/lst  

TS  

tst  MFS  

hst  

fall  

slow  rise/aggrada>on  rapid  rise  

rapid  rise/retrograda>on  

Slowing  rise/aggrada>on  

Slowing  rise/prograda>on  

h@p://d32ogoqmya1dw8.cloudfront.net/files/NAGTWorkshops/sedimentary/ac<vi<es/Exercise_1_instruc<ons.pdf  

Exercises  -­‐  Measured  Sec<ons  

There  are  a  number  of  exercises  online  for  the  Book  Cliffs,  which  I  have  used  in  the  past;  however,  with  a  strong  collec<on  of  photos  and  samples,  as  shown  in  previous  slides,  these  can  be  replaced  with  personal  materials  that  allow  students  to  construct  sec<ons  based  on  their  own  observa<ons.  

Exercises  –  Regional  Correla<on  

These  exercises  from  the  SEPM  Strata  website  will  be  complimented  with  photos  I  have  taken  of  the  actual  measured  sec<on  locali<es.  

The  Guidebook  

This  is  a  semester-­‐long,  loosely-­‐defined  project,  in  which  students  create  a  “guidebook”  to  teach  sedimentary  geology  principles  and  concepts  as  though  they  were  leading  a  field  trip.    I  provide  a  bank  of  several  hundred  photos  that  they  peruse  and  choose  from  to  show  what  they  want  to  convey.    They  may  also  use  outside  sources,  such  as  Google  Earth  and  published  literature.  

Virtual  Field  Trip  (in  development)  

I  am  currently  working  on  a  virtual  “field  trip”  that  I  will  use  to  both  introduce  and  to  summarize  the  case  study.  

Exercises  -­‐  Other?  

This  one’s  for  Tom  and  others  who  might  have  access  to  a  stream  table  with  a  subsiding  basin,  in  which  pa@erns  very  similar  to  those  of  the  Book  Cliffs  can  be  generated.    I  will  be  a@emp<ng  this  in  the  fall  with  the  new  BYU-­‐Idaho  table.  

Concluding  Ques<ons  

•  What  do  you  see?  (interbedded  sandstone  and  mudstone)  •  What  formed  the  bedding?  (changes  in  energy  condi<ons)  •  Why  are  energy  condi<ons  different?  (water  depth)  •  Are  there  any  ver<cal  trends  in  the  bedding?  (sand/mud  ra<o)  •  What  is  responsible  for  the  ver<cal  trend?  (base  level  change)  •  What  causes  base-­‐level  change  (eustasy  and  tectonics)  •  Does  this  succession  reflect  base  level  rise  or  fall?  (mostly  rise)  •  Does  this  succession  reflect  shoreline  transgression  or  regression?  

(regression)  •  What  else  might  impact  the  pa@ern?  (sedimenta<on  rate)