Shackleton fracture zone; no barrier to early circumpolar ocean circulation
Shackleton fracture zone; no barrier to early circumpolar ocean circulation
Geology (Boulder) (September 2004) 32 (9): 797-800
- Antarctic Circumpolar Current
- basalts
- basins
- Cenozoic
- climate change
- crust
- currents
- Drake Passage
- dredged samples
- Eocene
- fracture zones
- gateways
- geochemistry
- geophysical methods
- geophysical profiles
- geophysical surveys
- igneous rocks
- lower Oligocene
- mid-ocean ridges
- ocean circulation
- ocean currents
- ocean floors
- Oligocene
- paleo-oceanography
- paleocirculation
- paleoclimatology
- Paleogene
- plate convergence
- plate tectonics
- polar regions
- pull-apart basins
- reflection methods
- Scotia Ridge
- seismic methods
- seismic profiles
- Southern Ocean
- surveys
- Tertiary
- trace elements
- upper Eocene
- volcanic rocks
- Shackleton fracture zone
The opening of Southern Ocean gateways was critical to the formation of the Antarctic Circumpolar Current and may have led to Cenozoic global cooling and Antarctic glaciation. Drake Passage was probably the final barrier to deep circumpolar ocean currents, but the timing of opening is unclear, because the Shackleton Fracture Zone could have blocked the gateway until the early Miocene. Geophysical and geochemical evidence presented here suggests that the Shackleton Fracture Zone is an oceanic transverse ridge, formed by uplift related to compression across the fracture zone since ca. 8 Ma. Hence, there was formerly (i.e., in the Miocene) no barrier to deep circulation through Drake Passage, and a deep-water connection between the Pacific and Atlantic Oceans was probably established soon after spreading began in Drake Passage during the early Oligocene.
