GEOLOGY 343L STRATIGRAPHY (Spring 2010)

what is stratigraphy

why is it important?

stratigraphic study of a foreland basin:

Uplift and erosion of hinterland =

deposition of foreland strata and

causes deformation to migrateinto the foreland.

why study foreland basins?

1) Deformation along the range margin2) insight into climate and tectonics3) structurally diverse

1) deformation along range margin-style, rates

2) stratigraphic changes -climate, tectonics3) history of orogen - erosional and deformational

Are the facies changes tectonic or climatic?When did the Tian Shan begin to grow?How is foreland deformation distributed within the basin?How have strain rates varied over time?

1) weathering & erosion

3) sedimentary environments

transport

5) burial & diagenesis

2) deposition

4) sedimentary structures (details of

rocks) 6) sedimentary rock classification

types of stratigraphy: soil

http://soils.usda.gov/education/resources/K_12/lessons/profile/profile.jpg

TarimBasin

?

?

litho & chronostratigraphychrono-stratigraphic

litho-stratigraphic

LITHOSTRATIGRAPHY

types of stratigraphy: volcanic

Woolford 2009 MS thesis

types of stratigraphy: glacial

Figure 4. δ18Oc (Vienna Peedee b e l e m n i t e , V P D B ) v e r s u s s t r a t i g r a p h i c l e v e l f o r ( A ) Thakkhola Formation and (B) Tetang Formation

Garzione C N et al. Geology 2000;28:339-342

©2000 by Geological Society of America

types of stratigraphy: chemical

Figure 4. δ18Oc (Vienna Peedee belemnite, VPDB) versus stratigraphic level for (A) Thakkhola Formation and (B) Tetang Formation. For individual mollusks that were microsampled for seasonal variations, highest and lowest δ18O values are shown.

techniques

sh ss c

stratig

raph

ic  le

vel  (m)

“paleosol”

laterally  correlatesw/  paleoyardang

“paleosol”

“aeolian+paleosol”

“aeolian”5

0

15

10

1  m

15  m

20  cm  aeolian  bedsgrade  laterally  into  paleosols

paleosol

0.5  m  trough  cross-beddedsiltstone  filling  shallow  depression

in  lacustrine  shaleA

C

BPartial  Lacustrine  

Section

observation

measurement

analysis & research

stratigraphic charts and columns

sh ss c

“paleosol”

laterally  correlatesw/  paleoyardang

“paleosol”

“aeolian+paleosol”

“aeolian”5

0

15

10

chart column

1) weathering & erosion

3) sedimentary environments

transport

5) burial & diagenesis

2) deposition

4) sedimentary structures (details of

rocks) 6) sedimentary rock classification

transport paths (ch 2)

transport paths (ch 2)

EROSION OF PARTICLES

TRANSITION ZONE

SEDIMENTATION OF

Cohesive cl

ay and silt

Noncohesive clay and silt

Sand

Cobbles andboulders

Grain size (mm)

Velo

city

(cm

/s)

PARTICLES ONTO BED

FROM BED

PebblesGranules Silt Clay

fig 2.7

types of sedimentary rocks

1) clastic (sandstone or shale)2) chemical precipitate (limestone

or gypsum)3) organic (coal or oil)

clastic rocks & their textures

clastic rocksconglomerate, breccia, sandstone, and shale

siliciclastic characteristics

graded beds

Volcanic breccia sed. breccia

clastic rocks: mineralogy

2) chemical

limestone

Limestone

evaporites

3) organic

Si02 precipitated