Scientific Drilling across Africa: Lakes Bosumtwi 04 and Malawi 05

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Scientific Drilling across AfricaLakes Bosumtwi
(04) and Malawi (05)
Christopher A. ScholzSyracuse University
Malawi PIs C. Scholz, T.C. Johnson, J. King,
A.S. Cohen, M.R. Talbot, L. Kalindekafe
Bosumtwi PIs J. Peck, C. Scholz, J.
Overpeck, J. King, P.Y.O Amoako, C. Koeberl, B.
Milkereit
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Climate change focus
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Outline

• Bosumtwi Operations
• Bosumtwi Science
• Malawi Operations
• Malawi Science
• What worked, what failed
• Recommendations to DOSECC from Africa Project
  PIs

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Lake Bosumtwi Ghana Northern Hemisphere Tropics
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Basin Framework

• Lake Bosumtwi, North Equatorial West Africa
• 1.1 ma, 10.5 km diameter meteorite impact crater
• 70 m-deep lake
• Closed basin and tropical rain gauge
• 310 m thick section of lacustrine sediments,
  overlying impact breccia and central uplift

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Airgun Seismic Profile (Depth Section)
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(No Transcript)
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(No Transcript)
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Airgun Seismic Profile with 04 Drill Holes
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Field Program/Scientific Results

• 6 Core sites, 13 holes
• 1700 m of continuous core
• Million-year, mainly continuous record
• Downhole geophysics
• Extreme changes in lake level
• Alternating varved (annually laminated) and
  non-laminated sediment sections

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Operational Summary

• Bosumtwi a shallow marine-type drilling
  program, albeit with challenging logistics
• DOSECC drilling vendor GLAD800
• PIs responsible for logistics, permitting, etc.
• Syracuse University provided support vessel
• Project success due to the efforts of 4 key
  individuals D. Altman, C. Delahunty, J.
  Greenberg and Operational PI J. Peck

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250 m
100 m
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Positive Outcomes

• Excellent core quality
• Excellent tool performance
• Redundant sampling of full sedimentary section
• Excellent ancillary geophysical and sample data
  sets

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Negative Outcomes

• Insufficient numbers of trained drilling staff
• Death of Kevin Loveland
• Only 65 of proposed core sections recovered
• Professional marine training?
• Inadequate equipment conditioning

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Lake Malawi East African Rift
Southern HemisphereTropicsintegrates
regionalclimate signal
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• Lake Malawi, Southern East Africa
• Extensional/oblique-slip basin, asymmetric
  subsidence
• 560 km long, 700 m deep
• Age 8 ma
• Rich facies distribution, diverse and ancient
  fauna

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Field Program/Scientific Results

• 2 Core sites, 7 holes
• 620 m of core, 383 m subbottom at Site 1B
• 1.5-2 million-year continuous record of tropical
  climate change
• Alternating varved (annually laminated) and
  non-laminated sediment sections

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Forcing of tropical climate change Precession
or high latitude forcing?
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Holocene varves
Stage 5E (?) varves

• 1500 m

• Livingstone Mountains

10 cm
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Operational Summary

• Malawi blue-water marine drilling program
• Very challenging logistics
• URI General Contractor
• Seacore Ltd. Drilling Contractor
• DOSECC responsible for drilling tools and dynamic
  positioning system
• PIs responsible for logistics, permitting, etc.
• ADPS Ltd. Provided marine manning

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Viphya Barge - 160 LOA, 800 tons
Seacore C-100
Accommodation Vans
DOSECC DP System
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Accommodation Vans
DOSECC DP System
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Accommodation Vans
DOSECC DP System
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Positive Outcomes

• Excellent core quality
• Excellent tool performance
• Superb real-time engineering
• Successful mating of DOSECC tools to deep-water,
  API drill string
• Outstanding DOSECC tool- and engineering-support

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Negative Outcomes

• Failure of key components of the DOSECC Dynamic
  Positioning system
• Excessive cost overruns associated with
  commissioning of the DP system
• Communications with PI group during logistical
  planning

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Recommendations

• Staffing of drill crews thru partnering with
  commercial operators
• Put more resources to engineering, tool oversight
  (e.g. figure out how to sample sand!)
• DOSECC general contracting most appropriate for
  domestic, onshore operations
• Farm out major marine ops (UNOLS, marine drilling
  firms?)
• Trust the PI team during logistical planning
• Dont oversell the program