PALEOGENE PALEOSOL OCCURRENCES IN THE SANTA MONICA MOUNTAINS, SANTA ANA MOUNTAINS AND IN THE SAN JOA

1
PALEOGENE PALEOSOL OCCURRENCES IN THE SANTA
MONICA MOUNTAINS, SANTA ANA MOUNTAINS AND IN THE
SAN JOAQUIN HILLS, SOUTHERN CALIFORNIA

• RAMIREZ, Pedro C.1, WHITE, Tim2, LEYVA, Sonjia
  M.1, and COLBURN, Ivan P.1,
• (1) Department of Geological Sciences, California
  State University, Los Angeles, 5151 State
  University Drive, Los Angeles, CA 90032
• (2) Earth and Environmental Systems Institute,
  The Pennsylvania State Univ, 2217 EES Building,
  University Park, PA 16802

2
(No Transcript)
3
Santa Monica Mountains (Solstice Canyon)

• Stratigraphy
• Paleosol interbedded with arkoses and mudstones
  of the Las Virgenes Sandstone
• Non-marine Simi Conglomerate
• Cretaceous Tuna Canyon Formation

Stratigraphy of a Section of the Las Virgenes
Sandstone and a part of the Simi
Conglomerate. Paleosol is in red Sandstones are
in yellow Mudstones orange Simi Conglomerate in
green Coal in green
Stratigraphic column of paleosol illustrating the
four distinct zones. Weathered sandstone in
pink Mottled zone in purple Pisolite zone in
orange Silicified pisolite interval in yellow.
4
Santa Monica Mountains (Solstice Canyon)

• Paleosol
• Nine meters thick
• Comprised of
• Silicified iron pisolite interval
• Zone of iron pisolites
• Mottled purple and white horizon
• Basal highly altered sandstone

5
Santa Monica Mountains (Solstice Canyon)
6
Santa Monica Mountains (Solstice Canyon)
7
Santa Monica Mountains (Solstice Canyon)

• Las Virgenes Sandstone
• Sedimentary structures and textures present
  suggest a high energy fluvial depositional
  environment
• Carbonaceous layers occurring at its base suggest
  vegetated emergent areas such as bars and levees.

Stratigraphy of a Section of the Las Virgenes
Sandstone and a part of the Simi
Conglomerate. Paleosol is in red Sandstones are
in yellow Mudstones orange Simi Conglomerate in
green Coal in green
Stratigraphic column of paleosol illustrating the
four distinct zones. Weathered sandstone in
pink Mottled zone in purple Pisolite zone in
orange Silicified pisolite interval in yellow.
8
Santa Ana Mountains (Riverside Quarry Rancho
Mission Viejo)

• Riverside Quarry
• Stratigraphy
• Paleosol
• Jurassic (?) Bedford Canyon Formation

9
Santa Ana Mountains (Riverside Quarry Rancho
Mission Viejo)

• Riverside Quarry
• Paleosol
• Cap of intensely weathered, biotite-rich arkoses
• Red and gray claystones (locally carbonaceous)
• Basal red and white kaolinite mottled zone with
  red-brown pisolites

10
Santa Ana Mountains (Riverside Quarry Rancho
Mission Viejo)

• Riverside Quarry
• Bedford Canyon Formation
• Steeply dipping and isoclinally folded and
  sheared argillites, sandstones, and cherts
• Paleosol rests on an erosional surface cut into
  top of formation

11
Santa Ana Mountains (Riverside Quarry Rancho
Mission Viejo)
Riverside Quarry A distant shot of the quarry
where the paleosol is exposed along the quarry
walls.
12
Santa Ana Mountains (Riverside Quarry Rancho
Mission Viejo)
Riverside Quarry A close-up of the red and white
mottled pisolitic zone.
13
Santa Ana Mountains (Riverside Quarry Rancho
Mission Viejo)

• Rancho Mission Viejo area
• Stratigraphy
• Paleosol
• Holtz Shale member, Late Cretaceous Ladd Formation

14
Santa Ana Mountains (Riverside Quarry Rancho
Mission Viejo)
Rancho Mission Viejo area A part of the
paleosol exposed on the quarry wall. The
pisolitic interval rests below the black coal
layer. A red and grey claystones overly the
coal. White arkoses cap the sequence.
15
Santa Ana Mountains (Riverside Quarry Rancho
Mission Viejo)
Rancho Mission Viejo area A distant shot of
another quarry wall showing white arkoses coal
interval is missing in this location. Pisolites
occur at the base of the wall.
16
San Joaquin Hills (Shady Canyon)

• Stratigraphy
• Non marine texturally immature arkoses and lithic
  arenites (Silverado Formation)
• Paleosol
• Marine sandstones and mudstones (Silverado
  Formation)

17
San Joaquin Hills (Shady Canyon)

• Paleosol 1
• Horizon D - a three meter thick pallid zone
• Horizon C - two meters of white sandy claystone
  composed entirely of quartz and kaolinite
• Horizon B - A two meter-thick mottled red and
  white laterite
• Horizon A - A 1.75 meter thick laterite sequence
  (pallid zone, grading up into a red and white
  mottled zone and capped by an hematite-rich zone)

18
San Joaquin Hills (Shady Canyon)

• Paleosol 1
• Quartz Arenite - An anomalous quartz-rich (90
  quartz) sandstone overlies the paleosols with a
  sharp contact.
• Grades laterally to the south into a saprolite

19
San Joaquin Hills (Shady Canyon)
20
San Joaquin Hills (Shady Canyon)
Station 14 is located on the south side of Shady
Canyon. Here the akosic sandstones have not been
subjected to the same degree of alteration as
those to the north and relict features can still
be distinguished.
21
San Joaquin Hills (Shady Canyon)
Saprolite, Station 14
22
Soil Classification Systems

• Soils are classified based upon physical and
  chemical characteristics.
• Two main soils classification systems used The
  Soil Survey Staff (1993, 1999) and FAO - UNESCO
  (1988).

23
Soil Classification Systems

• Duchaufour (1982) recognized that these
  classification systems do not take into account
  the conditions necessary for soil formation,
  especially in regards to tropical / residual
  soils
• Retallack (1997) compiled a system specifically
  for paleosols

24
Soil Classification Systems

• Duchaufour (1982) has determined that there are
  three phases of the weathering cycle for tropical
  environments
• fersiallitisation, where 21 clays (micas,
  chlorite) are dominant
• ferrugination, characterized by kaolinite and 21
  clays (smectite, illite)
• ferrallitisation, dominated by kaolinite and
  gibbsite.

25
Soil Classification Systems
26
Typical Lateritic Soil Formation

• Retallack (1997)
• a red soil "cap"
• the laterite,
• a red, hematite-rich clay
• a "pallid zone" or a white clay zone that may or
  may not contain mottles
• a "white china clay"
• the saprolite
• the parent rock

27
Typical Lateritic Soil Formation

• hot, humid areas
• rainfall greater than 59 inches
• mean temperature greater than 77 F.
• All minerals except quartz are weathered out via
  hydrolysis.
• Kaolinite forms as the primary clay mineral,
  especially in quartz- rich parent rocks and where
  drainage is poor.
• Hematite forms where the soil is subject to
  seasonal dry periods.

28
Are the Southern CA Paleosols Laterites?

• Typical Laterite
• Primarily Composed of
• Hematite
• Kaolinite
• All other minerals but quartz leached out
• "Typical" Laterite Profile
• Fe Crust (ferricrete)
• Mottled Zone
• Pallid Zone
• Saprolite
• Parent Rock

• Solstice Canyon
• Primarily Composed of
• Hematite
• Kaolinite
• Quartz is the only other mineral present
• Paleosol Profile
• Iron Pisolites
• Mottled Zone
• - - - - -
• Highly Altered Sandstone

29
Are the Southern CA Paleosols Laterites?

• Typical Laterite
• Primarily Composed of
• Hematite
• Kaolinite
• All other minerals but quartz leached out
• "Typical" Laterite Profile
• Fe Crust (ferricrete)
• Mottled Zone
• Pallid Zone
• Saprolite
• Parent Rock

• Riverside Quarry
• Primarily Composed of
• Hematite
• Kaolinite
• Quartz is the only other mineral present
• Paleosol Profile
• Red Grey Claystone
• Mottled Zone w/ pisolites
• - - - - -
• - - - - -

30
Are the Southern CA Paleosols Laterites?

• Typical Laterite
• Primarily Composed of
• Hematite
• Kaolinite
• All other minerals but quartz leached out
• "Typical" Laterite Profile
• Fe Crust (ferricrete)
• Mottled Zone
• Pallid Zone
• Saprolite
• Parent Rock

• Rancho Mission Viejo
• Primarily Composed of
• Hematite
• Kaolinite
• Quartz
• Coal
• Paleosol Profile
• Red Green Claystone
• Sandy to Pure Coal Zone
• Pallid Zone w/ pisolites
• - - - - -

31
Are the Southern CA Paleosols Laterites?

• Typical Laterite
• Primarily Composed of
• Hematite
• Kaolinite
• All other minerals but quartz leached out
• "Typical" Laterite Profile
• Fe Crust (ferricrete)
• Mottled Zone
• Pallid Zone
• Saprolite
• Parent Rock

• San Joaquin Hills
• Primarily Composed of
• Hematite
• Kaolinite
• Quartz is the only other mineral present
• Paleosol Profile
• Fe Crust (ferricrete)
• Mottled Zone
• Pallid Zone
• ??
• (Base of sequence not exposed)

32
Chemical Data
1. Nesbitt, H.W., and Young, G.M., 1982, Early
Proterozoic climates and plate motions inferred
from major element chemistry of lutites Nature,
v. 299, p. 715-717. 2. Retallack, G., 2001,
Soils of the past An introduction to
paleopedology, Blackwell Science, 2nd edition,
404 p.
33
Solstice Canyon

• CIA and Total Fe/Al profiles, Solstice Canyon
• CIA values gt80 are characteristic of deeply
  weathered soil profiles.

34
Solstice Canyon

• Data are suggestive of an oxisol soil profile
• the ancient unsaturated zone (horizon 5)
• a zone of carbonate precipitation (pisolites)
  within the ancient zone of fluctuating water
  table (horizons 3 and 4)
• and a deeply weathered zone beneath the ancient
  water table (horizons 1 and 2)

35
Conclusions

• Paleosols from all four locations fit the
  definition of a residual soil
• Solstice Canyon and San Joaquin Hills paleosols
  a laterite
• Laterites and kaolinites typically form in
  tropical and subtropical climates

36
Conclusions

• Evidence
• Petrologic Data
• Paleontological Data (Sundberg and Warter, 1984)
• Geochemical Data
• CIA and hydrolysis values are more in line with
  soils generated through extensive weathering.

37
Conclusions

• Problems
• Age constraints for formations (Las Virgenes
  Sandstone and Silverado Formations) are
  containing the paleosols not strong
• based mostly on section correlations.

38
Conclusions

• Future work
• These Southern California paleosols are similar
  to those of the Eocene Ione Formation
• Are these paleosols related?
• Stratigraphic work
• Petrologic analysis
• Palynological analysis

39
The end

• . . . For now!