65ma of climate change: biogeography of the cenozoic era
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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. Start:. - PowerPoint PPT PresentationTRANSCRIPT
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)