Further Development of a Precambrian Plate Model by Bruce Eglington, U. of Saskatchewan: 2013/Third...
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Transcript of Further Development of a Precambrian Plate Model by Bruce Eglington, U. of Saskatchewan: 2013/Third...
Further development of a Precambrian plate model and its application in identifying sediment provenance
Bruce Eglington University of Saskatchewan
Overview
► Data available to aid model development ► Current status of model
Improvements to plate boundary delineation Meso- and Neo-Proterozoic and early
Palaeoproterozoic/Neoarchaean Better visualising different types of mineralisation Demo model
► Definition of Precambrian plates and relevance to Phanerozoic geology
► Additional constraints provided by detrital zircon provenance assessments
Overview
► Data available to aid model development ► Current status of model
Improvements to plate boundary delineation Meso- and Neo-Proterozoic and early
Palaeoproterozoic/Neoarchaean Better visualising different types of mineralisation Demo model
► Definition of Precambrian plates and relevance to Phanerozoic geology
► Additional constraints provided by detrital zircon provenance assessments
Geochronology
~ 106,000 records in the DateView geochronology database
Dyke swarms
~ 6,500 records in the StratDB LIP database, many with geospatial information in ArcMap compilation
Deposits
~ 15,000 deposit/mineralisation records in the StratDB database, most with latitude and longitude information. ~4,500 have Pb isotope data
Nd
T DM
Overview
► Data available to aid model development ► Current status of model
Improvements to plate boundary delineation Meso- and Neo-Proterozoic and early
Palaeoproterozoic/Neoarchaean Better visualising different types of mineralisation Demo model
► Definition of Precambrian plates and relevance to Phanerozoic geology
► Additional constraints provided by detrital zircon provenance assessments
Geophysical constraints
U-Pb Formation Ages
Nd TDM
Geographic extent of dated lithostratigraphic units
Interpreted maximum age of blocks
Overview
► Data available to aid model development ► Current status of model
Improvements to plate boundary delineation Plate motion constraints Meso- and Neo-Proterozoic and early
Palaeoproterozoic/Neoarchaean Better visualising different types of mineralisation Demo model
► Definition of Precambrian plates and relevance to Phanerozoic geology
► Additional constraints provided by detrital zircon provenance assessments
► Palaeomag constraints are primary – modelled using GPlates Paleogis plugin for ArcMap Customised software written by BE
Constraints for Palaeogeographic Reconstructions
► Palaeolongitude Estimated based on the orthoversion concept presented by
Mitchell and Evans (2012)
Most likely centroid of supercontinent
Constraints for Palaeogeographic Reconstructions
Palaeogeographic Reconstructions
► Extensive set of plates based on Geology Aeromagnetic and Gravity Anomalies
► Palaeomag constraints are primary – modelled using GPlates Paleogis plugin for ArcMap Customised software written by BE
► Consider structural vergence directions
Overview
► Data available to aid model development ► Current status of model
Improvements to plate boundary delineation Plate motion constraints Meso- and Neo-Proterozoic and early
Palaeoproterozoic/Neoarchaean Better visualising different types of mineralisation Demo model
► Definition of Precambrian plates and relevance to Phanerozoic geology
► Additional constraints provided by detrital zircon provenance assessments
Available Palaeogeographic Models
► Phanerozoic Paleomap (Chris Scotese) Earthbyte (GPlates) Various commercial models
► Meso- to Neo-Proterozoic IGCP 440 (Li et al., 2008) Various other ‘snap-shots’
► Palaeoproterozoic to Archaean Various, mostly schematic, ‘snap-
shots’ Eglington et al. (2013) Pisarevsky et al. (2013) Pehrsson et al. (2013)
Paleomap
IGCP 440
Rogers and Santosh, 2002 Zhao et al, 2002
Evans and Mitchell, 2011
Some available Palaeogeographic Reconstructions for Nuna (Columbia)
► Started with Palaeoproterozoic Nuna
► Working forward in time through Mesoproterozoic to Neoproterozoic Rodinia
► Also extending back towards Neoarchaean
Overview
► Data available to aid model development ► Current status of model
Improvements to plate boundary delineation Plate motion constraints Meso- and Neo-Proterozoic and early
Palaeoproterozoic/Neoarchaean Better visualising different types of mineralisation Demo model
► Definition of Precambrian plates and relevance to Phanerozoic geology
► Additional constraints provided by detrital zircon provenance assessments
Overview
► Data available to aid model development ► Current status of model
Improvements to plate boundary delineation Plate motion constraints Meso- and Neo-Proterozoic and early
Palaeoproterozoic/Neoarchaean Better visualising different types of mineralisation Demo model
► Definition of Precambrian plates and relevance to Phanerozoic geology
► Additional constraints provided by detrital zircon provenance assessments
Overview
► Data available to aid model development ► Current status of model
Improvements to plate boundary delineation Plate motion constraints Meso- and Neo-Proterozoic and early
Palaeoproterozoic/Neoarchaean Better visualising different types of mineralisation Demo model
► Definition of Precambrian plates and relevance to Phanerozoic geology
► Additional constraints provided by detrital zircon provenance assessments
Reconstruction at 1500 Ma Ages from 1500 – 1580 Ma
W. Australia
N. Australia
Gawler
Mawson
Siberia
Baltica
Amazonia
W. Africa
Superior
Slave
W. Gneiss Complex
VMS U Ni-Cu-PGE
Plutonic / volcanic crystallization
Cooling Metamorphic
Basement control of younger
sedimentation
From Paul Ramaekers (2011)
From Paul Ramaekers (2011)
Basement control of younger
sedimentation
From Paul Ramaekers (2011)
Basement control of younger
sedimentation
Basement control of younger
sedimentation
From Tankard et al (2009)
Basement control of younger
sedimentation
From Tankard et al (2009)
Basement control of younger
sedimentation
From Tankard et al (2009)
Basement control of younger
sedimentation
From Tankard et al (2009)
Overview
► Data available to aid model development ► Current status of model
Improvements to plate boundary delineation Plate motion constraints Meso- and Neo-Proterozoic and early
Palaeoproterozoic/Neoarchaean Better visualising different types of mineralisation Demo model
► Definition of Precambrian plates and relevance to Phanerozoic geology
► Additional constraints provided by detrital zircon provenance assessments
Pro
ba
bil
ity
Grain Age (Ma)
Un
it A
ge
(M
a)
Kaapvaal
3600
1200
1200 3800
1940 Ma
Neylan Fm
Lower Selika Formation
Pilbara
Zimbabwe
Kaapvaal
From Tankard et al (2009)
Detrital provenance
Detrital zircon age spectra for Cape and Karoo sediments
Detrital zircon age spectra for Cape and Karoo sediments
Detrital zircon age spectra for Cape and Karoo sediments
U-Pb Formation Ages
U-Pb Formation Ages
Cape-Karoo potential provenance sources 850 – 960 Ma
Detrital provenance
Acknowledgements ► IGCP 509 project ► University of Saskatchewan and NSERC
Databases housed at U of S
► Geological Survey of Canada Ore deposit information (especially via Lesley Chorlton) + various coworkers
► Various mining companies for student support and money to purchase hardware and software
Newmont Areva De Beers
► Paleogis plugin for ArcMap The Rothwell Group Chris Scotese
► GPlates software Dietmar Mueller and John Cannon in Sydney, Australia
► Various software companies for providing academic versions Embarcadero Steema AtoZed HK Systems