GEOL 553 LECTURE - PowerPoint Presentation

Slide1

GEOL 553 LECTURE 16

Types

of Evidence

Glacial Sediments

Periglacial Sediments

Paleosols

Aeolian Deposits

Lake Level Records

Cave Sediments and Carbonate Deposits

Lake Sediments

Deep Sea Sediments

Ice Core

Stratigraphy

Biological Evidence

Microfossils

Pollen

Diatom

Macrofossils

Plants

Insects

Mollusca &

Ostracoda

& Foraminifera &

Coccolithophores

MammaliaSlide2
Slide3

http://www.gly.uga.edu/railsback/GeologicalDiagrams2.htmlSlide4

http://spot.pcc.edu/~kleonard/images/SoilHorizons.jpg

https://classconnection.s3.amazonaws.com/181/flashcards/1021181/jpg/10-14291CD831611F3BD29.jpgSlide5

http://www.gly.uga.edu/railsback/GeologicalDiagrams2.htmlSlide6

6

Latitudinal variations:

Between 38°N and S = net energy surpluses

Poleward of 38

o

= net energy deficits

Winter hemispheres - Net energy deficits poleward of 15

oSlide7

The idealized wind and surface

-

pressure distribution over a uniformly water-covered rotating earth

.

(Show Video)Slide8

http://www.gly.uga.edu/railsback/GeologicalDiagrams2.htmlSlide9

http://eusoils.jrc.ec.europa.eu/projects/soil_atlas/pages/10.html

The profile on the

right shows

a classic A-B-C sequence of soil horizons, with

color

differences reflecting the relative distributions of organic matter and iron oxide produced by the weathering of minerals in the soil

(photo J. Hollis)

.

http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/survey/class/taxonomy/?

cid=nrcs142p2_053577

http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/edu/?

cid=nrcs142p2_054315

Soil Taxonomic Guide

Soil Description Video TutorialsSlide10
Slide11
Slide12

http://www.nzsoils.org.nz/PageFiles/119/images/Soil%20Consistence%20Tables-Failure%20Class%20Table.png

http://www.nzsoils.org.nz/PageFiles/119/images/Soil%20Consistence%20Tables-Strength%20Class%20Table.pngSlide13

Paleosols

Examples of alluvial-stratigraphic sections from the Central Great Plains with radiocarbon dated late Pleistocene and early Holocene buried soils

.

At

the

Clemance

Section in

the lower Smoky Hill River valley of east-central

Kansas,

three buried soils 2, 3, and 4) characterized by thick,

cumulic

, organic-rich horizons span the YDC.

(

photo by R.D. Mandel

).

A single buried soil at the

Kanorado

site in northwestern Kansas contains stratified

Clovisage

and

Folsom cultural deposits.

(photo

by R.D. Mandel).Slide14

Paleosols

The stratigraphic sequence of the Val

Sorda

profile.

Ages (in

yr BP)

from

Cremaschi

et al. (1987) and

Accorsi

et al. (1990); OSL: Optical

Stimulated Luminescence

.Slide15

Aeolian Sediments

Loess deposits, composed of fine wind-blown dust produced by the grinding action of glaciers, indicate the former presence of ice sheets in locations around the Northern Hemisphere. This exposure of loess is near Palouse, Washington.

(Photograph copyright Donald P.

Schwert

, North Dakota State University)

http://earthobservatory.nasa.gov/Features/Paleoclimatology_Speleothems/Slide16

Aeolian Sediments

Diagram showing the nature of the loess stratigraphic record. In most regions, including much of North America, Europe, and China, loess was deposited during glacial periods and soils were formed during interglacial periods. Soils that become buried by younger loess are called "

paleosols

."

http://gec.cr.usgs.gov/archive/eolian/task2.shtml

Photograph showing an unusually complete, long-term loess-

paleosol

record near Elba, Nebraska; the last interglacial-glacial cycle is represented by the Sangamon

paleosol

(last interglacial) and Peoria loess (last glacial). The modern soil at top began forming at the beginning of the present interglacial period.Slide17

Aeolian Sediments

Using lead (

Pb

) isotopes in K-feldspar as "fingerprints" for determining the sources of last-glacial (Peoria) loess in eastern Colorado.

Pb

isotopes define distinct compositions for

South Platte River silts (possibly of glacial origin)

and siltstones of the

White River Formation (non-glacial origin)

. Loess silts plot in both fields and between the two fields, indicating that both source sediments were important.

(

Aleinikoff

et al., 1999, Geological Society of America

Bulletin)

http://gec.cr.usgs.gov/archive/eolian/task2.shtmlSlide18

Aeolian Sediments

Map

showing the Laurentide ice sheet during the last glacial period and the winds that are modeled to have developed from the high pressure cell over it. Note that these winds differ from the past winds that have been inferred from loess deposits

.

See Muhs &

Bettis

, 2000, Quaternary Research.

http://gec.cr.usgs.gov/archive/eolian/task2.shtmlSlide19

Aeolian Sediments

Loess–palaeosol succession at Baoji, in the southern Loess Plateau, north-central China (for location see

Figure 3.27

) showing thirty-two palaeosol units spanning the last 2 Ma. The

palaeomagnetic

timescale (see Figure 5.34) is shown on

the right

. B/M –

Brunhes

–

Matuyama

boundary c. 0.78 Ma; J – Jaramillo event, 1.07–0.99 Ma; O – Olduvai event; 1.956–1.79 Ma;

M/G –

Matuyama

–Gauss boundary, c. 2.6 Ma (from Ding et al., 1994).Slide20

Lake Levels

The reconstructed

Samra

lake-level curve. a) A photograph of the PZ7 columnar section with the local stratigraphic cycles. b) The lake-level curve between ?140 and 50 ka. Black dots mark heights of absolute dating by U/Th. The

Lisan

lake-level curve is adapted from

Bartov

et al. (2003).

Samra

lake levels are estimated and represent maximum or minimum heights. c) Stratigraphy of the DSB lacustrine deposits. Am. stands for

Amora

. d) Timing of Marine Isotope Stages (following EPICA community members, 2006

).

http://marsci.haifa.ac.il/labs/petrolab/pub/80.htmlSlide21

U/Th Age Control

http://www.geo.arizona.edu/Antevs/ecol438/uthdating.html

Uranium-Thorium

age control is

based on the detection by mass spectrometry of both the parent (

234

U) and daughter (

230

Th) products of decay, through the emission of an alpha particle. 

The

decay of Uranium 234 to Thorium 230 is part of the much longer decay series

beginning

in 

238

U and ending in 

206

Pb. 

For

Uranium-Thorium

age control

,

the initial ratio of 

230

Th/

234

U at the time of sample formation must be known or calculated. With time, Thorium 230 accumulates in the sample through radiometric decay. The sample age is based on the difference between the initial ratio of 

230

Th/

234

U and the one in the sample being dated. The method assumes that the sample does not exchange 

230

Th or 

234

U with the environment (i.e., that it is a closed system.) The method is used for samples that can retain Uranium and Thorium, such as carbonate sediments, bones and teeth. Ages between 1000 and 300,000 years have been reported.Slide22

Lake Levels

http://www.fop.cascadiageo.org/?page_id=192Slide23

Caves

Generalized cross-section of a cave with various types of sedimentary infill and associated biological remains

(

modified from

http://historyofgeology.fieldofscience.com/2010_10_01_archive.html).Slide24

Caves

a) Cross-sectioned surface of a stalagmite from

Akçakale

Cave, northeast Turkey revealing annual growth

layers spanning

the last c. 500 years, the chronology confirmed by U-series

age control.

Cross-sectioned surface of a small stalagmite from

Rukiessa

Cave, southeast

Ethiopia, spanning the last century. Seasonal layers are indicated by

color

variations that reflect impurities within

the drip

waters in the cave. Samples 1–3 mm in thickness were drilled along a continuous transect (light shading) that enabled

seasonal climatic

variations

and land-use changes to be reconstructed

(Baker et al., 2007; Blyth et al., 2007)Slide25

Caves

Composite δ

18

O curve constructed from twenty-one overlapping speleothem records for the past 185 ka from

Soreq

Cave, Israel. The black circles at the top show the positions of samples dated by TIMS U-series (section 5.3.4.2)

(after

Ayalon

et

al., 2002).Slide26

Deep Sea Sediments

Heinrich layers in

deep-ocean sediments

. The two core

segments (right

) were recovered from

the northwestern

Labrador Sea

between Baffin

Island and Greenland (

lat. 61°30’N

; long. 58°26’W

). Sedimentological

analyses (left)

show that

the Heinrich layers

are characterized by significantly higher levels of carbonate and

mass magnetic

susceptibility (MSS), and

in the

cores they are reflected in a

color

change

from grey to brown (‘a’ and ‘

b’ mark

the end of Heinrich events 1

and 2

, respectively). The two

Heinrich layers

shown here are

radiocarbon ages of 14.7–14.2

ka BP (c.

18.0–17.4 k

cal. BP) and 21.5–19.5 ka BP (

c. 25.6–23.3

k cal. BP), and are

coeval with

Heinrich events 1 and 2 in

the eastern

North

Atlantic.

(sedimentological

data from

Andrews &

Tedesco,

1992; photographs by John

Andrews, University of

Colorado, USA

).Slide27

Ice Core Stratigraphy

Annual ice layers exposed in the

Quelcayya

ice cap

, Peru (photograph by Lonnie G. Thompson, Ohio

State University

, USA).Slide28

Ice Core Stratigraphy

Seasonal variations in chemistry, dust content and

stable oxygen

isotope ratios in ice layers in a section of

the

NorthGRIP

core. Slide29

Ice Core Stratigraphy

Continuous δ

18

O profiles through five Greenland ice cores. Some of the warm Greenland Interstadials (GI) of

the

Dansgaard

–

Oeschger

(DO) cycles are defined by reference to the GRIP δ

18

O record and are numbered to the right of each

profile; these

were used to guide correlation between the isotope traces. Some of the cold Greenland Stadials (GS) are also

numbered to

the left of the GRIP record

(after Johnsen et al., 2001).Slide30
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