Geoscience Reference
In-Depth Information
Tabl e 3 . 3 .
Global environmental changes of the past 130 million years
TECTONICS, CLIMATE, VEGETATION: NORTHERN PERSPECTIVE
1. India-Asia contact: Himalayan uplift (
45 Ma)
25 Ma)
3. Africa meets Europe: Mountain building (15 Ma)
4. Tethys Sea shrinks: Rainfall less and more seasonal
5. Forest gives way to savanna woodland and grassland in Africa and Asia
6. Messinian Salinity Crisis: Africa isolated from Eurasia (5.96-5.33 Ma)
7. Pliocene hominids appear in Africa (5 Ma)
8. Late Pliocene cooling and tropical desiccation (2.6 Ma)
9. First stone tools appear in Ethiopia:
Homo habilis
(2.5 Ma)
TECTONICS, CLIMATE, VEGETATION: SOUTHERN PERSPECTIVE
1. India separates from Australia-Antarctica (
2. East Africa: Uplift and rifting (
128 Ma)
2. Australia first separates from Antarctica (
90 Ma)
3. Tasmania-Antarctic Passage opens (
34 Ma)
30 Ma)
5. Antarctic cooling and thermal isolation
6. Ice cap growth in Antarctica (34 Ma)
7. Cooling of the Southern Ocean
8. Australia moving north into dry subtropical latitudes
9. Forest replaced by woodland in Australia
10. Miocene ice expansion in East Antarctica
11. Late Miocene ice sheet in West Antarctica
12. Woodland gives way to savanna grassland in Australia, South America and
South Africa
13. Drainage disruption, desiccation and faunal extinctions in Australia
TECTONICS, OCEAN CIRCULATION, GLACIATION
1. Laurasia break-up: North Polar cooling (15 Ma)
2. Antarctic cooling and ice build-up (34 Ma)
3. Cold Antarctic bottom water (34 Ma)
4. North Atlantic deep water (12 Ma)
5. Closure of Panama seaway: Arctic ice (3.5 Ma)
6. North American ice cap build-up (2.5 Ma)
7. Quaternary low-amplitude, high-frequency 40 ka glacial cycles (2.5 Ma)
8. Quaternary high-amplitude, low-frequency 100 ka glacial cycles (
4. Drake Passage opens (
0.9 Ma)
9. Glacio-eustatic sea level fluctuations
10. Alternating glacial desert expansion and interglacial desert contraction
began early in the Mesozoic (
Tabl e 3 . 3
;
Figures 3.1
and
3.2
). Disintegration of the
Pangaea supercontinent and of the super-ocean Tethys began in the Jurassic around
180 Ma ago (Kearey and Vine,
1996
; Williams et al.,
1998
, pp. 11-21). The break-up
of Pangaea was associated with higher levels of igneous activity along developing
rift systems and the development of new continental margins. Early rifting led to the
initial opening of the proto-Atlantic Ocean, with the emergence of the other oceans
during the Mesozoic, culminating in the formation of the Southern Ocean early in
the Cenozoic, from about 50 Ma onwards (
Tabl e 3 . 3
). Rifting in East Antarctica at
