Young Drowned Carbonate Platforms in the Florida Straits

1
Young Drowned Carbonate Platforms in the Florida
Straits

• Kelly Bergman, Gregor Eberli
• and Jose Luis Masaferro

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Florida-Bahamas Region

• Historically stable area
• Early work attributed disintegration of Middle
  Cretaceous carbonate banks to global carbonate
  crisis (Schlager and Ginsburg, 1981)
• Since then a passive margin

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Tectonic Control on Drowning Events

• Early Cretaceous platforms segmented due to
  faulting during Bahama-Cuban collision (Eberli
  and Ginsburg, 1989 Masaferro, 1997)
• Late compression is responsible for drowning of
  Cay Sal Bank that extended from Cuba to Florida
  (Masaferro, 1997 Masaferro et al., 1999)

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Key Points

• Reevaluate the episodic drowning of carbonate
  platforms in the Straits of Florida using a new
  Paleogene-Neogene age model
• Drowning of Cay Sal Bank occurred stepwise
  throughout the Paleogene and into the Miocene
• Segmentation due to Bahama-Cuban tectonics
  continued into the Neogene

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Tectonic Setting
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Masaferro and Eberli (1999)
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(No Transcript)
8
Late Cret.-Paleocene
Paleocene- Early Eocene
Early to Middle Eocene
Middle Eocene to Plio-Pleistocene
Masaferro (1997)
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Masaferro (1997)
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Multi-channel seismic dataset
Great Isaac
Florida
GBB
ODP Leg 166
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Ages from ODP Leg 166 Transect
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• Southeastern platform margin
• Two backstepped margins
• Fault-bounded

S
Ma
9.4
10.7
23.7
Late Oligocene
5 km
13

• Southeastern platform margin
• Two backstepped margins
• Fault-bounded

S
5.4
8.7
15.9
23.7
5 km
14
NE
Ma
3.6
5.4
8.7

• Drowning between 5.4-8.7 Ma

5 km
15

• Northern platform margin
• Drowning in Late Oligocene

S
Ma
3.6
9.4
12.2
10.7
15.9
15.1
Late Oligocene
Late Cretaceous
5 km
16
S
Ma
5.4
9.4
23.2
Late Cretaceous
Late Oligocene
5 km

• Northern platform margin
• Inverse along faults
• Onlap surfaces related to fault movement

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• Eastern platform margin

W
Ma
8.7
10.7
12.2
15.1
18.3
23.2
Late Oligocene
5 km
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Minimum ages of drowned platforms
Late Oligocene
Late Miocene
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History of platform margins
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Conclusions

• Drowning events of shallow carbonate platforms
  controlled by regional tectonics
• Segmentation of shallow water platforms related
  to Bahama-Cuban tectonics continued throughout
  the Paleogene, Neogene, and maybe until the Early
  Pliocene
• Cay Sal Bank underwent two distinct backstepping
  and drowning episodes

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Conclusions

• First episode overlain by Upper Oligocene
• Second episode overlain by Upper Miocene to
  Lower Pliocene
• Reverse and normal faults affect the platform
  margins and basinal sediments into the Neogene

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Acknowledgements

• Ralf Weger
• Kelley Steffen
• Comparative Sedimentology Laboratory
• Ocean Drilling Program
• Spectrum Energy Information Technology