by t. neil irvine, jens christian andersen and c. kent brooks
DESCRIPTION
Included blocks (and blocks within blocks) in the Skaergaard intrusion: Geologic relations and the origins of rhythmic modally graded layers. By T. Neil Irvine, Jens Christian Andersen and C. Kent Brooks. Autolith blocks and rhythmic modally graded layers in the Skaergaard intrusion. - PowerPoint PPT PresentationTRANSCRIPT
Included blocks (and blocks within blocks) in the Skaergaard intrusion: Geologic relations and the origins of
rhythmic modally graded layers
By T. Neil Irvine, Jens Christian Andersen and C. Kent Brooks
Autolith blocks and rhythmic modally graded layers in the
Skaergaard intrusion
Presented by: Angelique Laurie
The Skaergaard intrusion: Introduction and emplacement
Fig 1: Skaergaard emplacement (Geological Society of America, November, pg 1401)
Skaergaard : Series’
• Layered Series
• Marginal Series
• Upper Border Series
The Skaergaard intrusion: Series’
Fig 2: Skaergaard shape and series’ (Origin of Igneous Layering edited by Ian Parsons, pg 205)
Fig 3: Skaergaard Series’ (www.union.edu/PUBLIC/GEODEPT/hollocher/skaergaard/
Skaergaard layering
1) Modally graded layers
2) Uniform/isomodal layers
3) Macro-rhythmic layers
4) Micro-rhythmic layers
Fig 4: Modally graded and uniform layers
(www.union.edu/PUBLIC/GEODEPT/hollocher/skaergaard/ )
Fig 5: Macro-rythmic layers (www.union.edu/PUBLIC/GEODEPT/hollocher/skaergaard/ ) Fig 6: Micro-rhythmic layers
(www.union.edu/PUBLIC/GEODEPT/hollocher/skaergaard/ )
Blocks and Block Structures1) Streamlining 2) Block impact structures
3) Fragmental layers
4) Trough layering structures
Fig 9: Fragmental layers (www.union.edu/PUBLIC/GEODEPT/hollocher/skaergaard/ )
Fig 7: Steamlining (Geological Society of America Bulletin, November, pg 1420)
Fig 10: Fragmental layers (Geological Society of America Bulletin, November, pg 1420)
Fig 8: Block impact structures (Origins of igneous layering, Ian Parsons, pg 218)
Deposition of modally sorted layers
1) Boundary flow seperation and reattachment
Fig 11: S-R cell (Geological Society of America Bulletin, November, pg 1438)
Deposition of modally sorted layers
2) Density surge currents
Fig 12:Density surge currents (Geological Society of America Bulletin, November, pg 1438)
Conclusion
Fig 13: Processes occuring in the western hal fof the Skaergaard magma chamber (Geological Society of America Bulletin, November 1998 pg 1442)
Comparison with Bushveld Igneous complex
Bushveld SkaergaardLocation South Africa Greenland
Age Precambrian Eocene
Size 66 000 km2 100 km2
Shape Flat funnel Oval
Magma injection Repeated Single
System and magma movement
Open feeder, non convecting
Closed feeder, convecting
Layering horizontal,rhythmic modally graded
concentric,rhythmic modally
graded
Blocks uncommon common
Value economic- platinum (chrome) scientific - “type locality”
Thank –you!