65Ma of climate change: biogeography of the Cenozoic

era

Mean annual temperatures in NW Europe and NW North America (reconstructed from pollen data) shown in red

Cenozoic climate change: the record from sub-Antarctic waters

thermal maximum

Pal(a)eocene biogeography

http://www.scotese.com/paleocen.htm

Start:

Northern hemisphere

biogeography in the early Cenozoic

(Paleocene/Early Eocene thermal

maximum @ 55My BP)

Sources: Bowen, G.M. et al. 2002. Mammalian Dispersal at the Paleocene/Eocene Boundary. Science 295: 2062 -

2065.Sluijs, A. et al., 2006. Subtropical Arctic Ocean temperatures during the Palaeocene/Eocene thermal

maximum. Nature, 441: 610-613.

Arctic Ocean fresh (floating mats of Azolla algae); CO2 ~2000 ppm (cf. 380 ppm @ PD) Arctic MAT increased from ~18°C (Paleocene) to ~23°C (cf. -20°C @

PD) Early mammals (ancestors of all major groups) likely originated in

Asia in late Paleocene and apparently migrated across the northern continents at or about the time of the thermal maximum.

Early Tertiary coal deposits, Axel Heiberg Island

(stumps are dawn redwood: Metasequoia)

Plant macrofossils from early Tertiary coalbeds, Axel Heiberg

Island

Oligocene palaeogeography

http://www.scotese.com/oligocen.htm

QuickTime™ and aTIFF (LZW) decompressor

are needed to see this picture.

Eugene

John Day N.M.

Major Eocene-Oligocene fossil flora

sites in the PNW

Eo-Oligocene biogeography of the Pacific NW

• John Day Fossil Beds National Monument, Oregon

• Current vegetation: sagebrush “high desert”; mean ann. ppt ~200 mm.

John Day chrono-stratigraphy

Deciduous riparian

forest (alder- elm-hickory-

walnut), east-central

Oregon(Whitecap Knoll beds;

late Eocene)

Eocene-Oligocene fossil

beds near Eugene, OregonWarm temperate forest (alder-oak-sycamore-

sweet clover [Meliosma], dawn

redwood [Metasequoia]

Source: Retallack, G.J. et al., 2004. Eocene-Oligocene extinction and paleoclimatic change near Eugene, Oregon. Geological Society of America Bulletin, 116, 817-839.

Source: Retallack, G.J. et al., 2004.

Mid-Cenozoic paleoclimate;

west-central Oregon

Eugene @ PD: MAT ~11°C; P ~1300 mm

Cenozoic climatic decline and

the onset of glaciation

What prompted Cenozoic climate decline and the onset of

glaciation?Main factors:1. Continental drift

Isolation of Antarctica and initiation of sub-Antarctic oceanic circulation; ice-sheet formationIsolation of Arctic Ocean; sea-ice formation

2. OrogenesisIsolation of continental interiors, particularly of Central Asia, as a result of uplift of the Himalayas and Tibetan Plateau. High altitude areas = more snow cover = high albedo = regional cooling.

The Quaternary: endpoint of

Tertiary cooling

Plio

cen

e

1.67 Ma

Ple

isto

cen

e

Colder - Warmer Ter

tiary

Q

uate

rnar

y

Holocene10 ka

When did the first cold

phase occur?

IRDIRD = iceberg-rafted detritus Colder - Warmer

Local extinctions after the first cold

phase

~ 2.4 Ma = beginning of Quaternary?

Vegetation of Late Pliocene Holland

cold

Ice and Change:Quaternary Biogeography

Nature of the evidence Chronology Fluctuating climates Glacial phases Interglacial phases

Iceworld: Wisconsinan glaciation

storm paths

Glacial - interglacial seesaw:

e.g. 9 glacial phases in last

0.7 Ma?

Polar

Polar

Cold continental

Oceanic

Palaeotemperatures

(50 - 20 ka BP) in Britain derived

from beetle assemblages

Assem

blage

l

lll

ll

l

Species ranges

Pollen analysis:

identification based on shape

and ornamentation

of grain

Pollen “rain”

Lakes

Bogs

Pollen analysis results:% pollen

and pollen influx

The last interglacial

- glacial cycle

Glacial / periglacial areas

~ 100 ka

slow cooling

quick w

arm

ing

quick w

arm

ing

European vegetation

distribution: 13 ka BP

(= late glacial)

Full-glacial vegetation of eastern North America

Laurentide Ice Sheet

Bio-indicators of lowered sea level in late Quaternary mammoth teeth freshwater peat oolites(= lake deposits)all continental shelves exposed in glacial phases

Exposed continental

shelves =

land bridges

Trans-Beringia mammal migrations during the

QuaternaryBeaverLynxSnow & mountain sheepMooseElkBearsWolverineWolfArctic foxArctic hareBisonMountain goatCoyoteKit fox

CamelsHorse

(and humans)

Beringia: Arctic fish refuge?

refuge? refuge?

Multiple trans-Beringian migrations: the Bison case

Bison priscus

Bison antiquus Bison bison

Quaternary fluctuations in precipitation in the western

US

http://wwwpaztcn.wr.usgs.gov/rsch_highlight/articles/200409.html

“Provo” relict

shoreline, Lake

Bonneville

Lake levelsin US

Southwest; full - late glacial

phase = “pluvial”

Elevation -

vegetation

relations, Grand

Canyon area:

full-glacial was cooler and wetter

Douglas-fir: a refuge

relict in the Mexican Sierras?

Glacial Interglacial

pine - fir forest

Glacial -interglacial migrations

(e.g.

Holocene) Glacial refuge

Interglacial range

Refuges and migrations: individualistic patterns

Refuges and migrations: aquatic biota

Postglacial

migration paths: aquatic biota Glacial refuges

Ranges and

refuges: the

tropical biotas

Inferred glacial refuges in

tropical areas:an extreme

view

Climatic deterioration

during interglacial

phases

?

Climatic optima in early interglacial time: the driving forces

Evidence for the Holocene hypsithermal

The early part of the Holocene is generally considered to have been a “climatic optimum” with higher temperatures (and lower rainfall?) than at present. Can you find evidence of this in the pollen records from the Pacific Northwest?

Elsewhere, the ‘hypsithermal’ may have been wetter: (e.g. the central Sahara)

Eroded lake beds,Taouendi

Rock art,Tassili Massif

Pollen evidence

(after Ritchie)