Duration 6 years 2009 - 2015inkaba.aeon.org.za/oldsite/publications/workshops/... · 2017-07-25 ·...
Transcript of Duration 6 years 2009 - 2015inkaba.aeon.org.za/oldsite/publications/workshops/... · 2017-07-25 ·...
Duration 6 years
South America – Africa reconstruction
(J.B. Françolin, 2000, AAPG Memoir 73)
Duration 6 years
2009 - 2015
Program coordinatorsProf. H.-P. Bunge (LMU Munich)Prof. J. Behrmann (IFM-Geomar)
Prof. M. Weber (GFZ + Uni Potsdam)Prof. M. Weber (GFZ + Uni Potsdam)
Steering committeeProf. A. Friedrich (LMU Munich), Prof. D. Gajewski (Uni Hamburg),
Prof. Dr. U.A. Glasmacher (Uni Heidelberg), Dr. Chr. Reichert (BGR), Dr. M. Scheck-Wenderoth (GFZ), Dr. W. Jokat (AWI),
Prof. H. Stollhofen (Uni Erlangen), Dr. R. Trumbull (GFZ), Dr. G. Unzelmann-Neben (AWI)
Scientific objectives
1. Mantle dynamics and
magmatic processes
Scientific objectives
2. Lithospheric structure, deformation
and breakup processes
3. Post-rift topographic evolution
and links to climate and tectonics
Scientific objectives
4. Sedimentary processes
and fluid systems
Scientific objectives
Development of South Atlantic rifted margins
Sierra do MarSierra de MantiquerraTaubaté
N-S.-Africa
Development of South Atlantic rifted margins
Sierra do MarSierra de MantiquerraTaubaté
N-Namibia
Aim:
Quantification the long-term dynamic topography evolution
of the South Atlantic passive continental margins
Causes and timing
With special emphasis on the reactivation of
WNW – ESE fracture zones – transfer zones
and
Neoproterozoic NNE-SSW shear zones
How to achieve?
Thermochronological dating techniques:
Apatite + Zircon fission tracks + (U-Th-Sm)/He
1-D Thermal + 3-D thermokinematic modelling
Total annealing of fission tracks at ~110 °C
Assumption: 10 Myr duration of the same temperature ………leads to.
Apatite fission-track technique
Partial annealing between 60 – 110 °C = PAZ
Nearly no annealing < 60 °C
Cooling below the temperature of ~ 110 °°°°C leads to accumulation of
fission tracks again.
Total annealing of fission tracks at ~240 °C at average defect conc.
Zircon fission-track technique
Assumption: 10 Myr duration of the same temperature ………leads to
Defect dependency of total annealing between 330 – 190 °C
No annealing < 190 °C
Cooling below the temperature of ~ 240 °°°°C leads to accumulation of
fission tracks again.
Using fission-track length distribution + 1-D t-T num. modelling
Exhumation rates are calculated for time intervalls
by assuming a therm. gradiant.
Bauer, Glasmacher, et al. (2009)
Total 4He diffusion out of apatite: ~75 °C = closure T.
Assumption: 1 Myr duration of the temperature …… leads to
Apatite and Zircon (U-Th-Sm)/He technique
Total 4He diffusion out of zircon: ~185 °C = closure T.
Cooling below the temperature leads to accumulation of 4He again.
75 (3.3) Ma
145 (3.3) Ma
Bauer, Glasmacher, Malikwisha, Mambo, Mutete (2009)
75 (3.3) Ma
Apatite fission track + apatite and zircon (U-Th-Sm)/He
+ computer code HeFTy
Long-term landscape evolution: rock uplift – erosion = surface uplift
Bauer, Glasmacher, Malikwisha, Mambo, Mutete (2009)
apatite FT + (U-Th)/He
Heat production,
Thermal diffusivity,
Topography change,
erosion rates
Rock uplift rate
3-D Thermo-kinematic modeling using the software code Pecube
Braun 2003
apatite FT + (U-Th)/He
ages dist.
comp. real data
Thermal diffusivity,
Temperature at upper and lower
boundary
Change of input data =
new modelling
Grobe, Glasmacher et al. 2011
Grobe , Glasmacher et al. 2011
Apatite fission-track ages (~ 110 °C/10 Ma)
~300 Ma
- ~ 50 Ma
~330 Ma
- ~ 20 Ma
~300 Ma
Karl, Glasmacher et al. 2011
~300 Ma
- ~ 30 Ma
Pattern in the spacial distribution of AFT-data
Karl, Glasmacher et al. 2011
Pattern in the spacial distribution of AFT-data
Extrusion of Parána-Etendeka flood volcanics (> 1,500 m)
+ formation of dikesRift
Basalt
Dev.-Jur.
Neoprot.
> 200 km
Basalt
Raab et al. 2005
Activation of NE- SW trending
Neoproterozoic shear zones ?Rift
202 (22) Ma
135 (62) Ma
115 (10) Ma
118 (23) Ma
158 (22) Ma
206 (27) Ma
244 (66) Ma
All are nearly
at the same
elevation
Activation
Neoprot.
shear zones
Hiruma ..Hackspacher et al. 2010
105 (10) Ma
105 (8) Ma
Movement
~ 110 Ma
Activation
Neoproterozoic
shear zones
in Namibia
Raab et al. 2005
1) 99 (9) Ma
2) 74 (6) Ma
5) 171 (12) Ma
6) 71 (5) Ma
All are nearly
at the same
elevation
3) 47 (4) Ma
4) 56 (5) Ma
Luft et al. 2005
elevation
1) 99 (9) Ma
2) 74 (6) Ma
5) 171 (12) Ma 6) 71 (5) Ma3) 47 (4) Ma
4) 56 (5) Ma
Luft et al. 2005
Movement ~ 70 Ma
Movement ~ 50 Ma
- Alkaline magmatism (Intrusions, subvolcanics, volcanics)
2 NW-SE trending belts
- Proposed formation of South American surface
Intrusion age of the Pocos de Caldas Massiv ~83 Ma
U-Pb, Fission Track, (U-Th-Sm)/He
Pocos de Caldas Alkaline Massiv
Souza Silva, Glasmacher et al. 2011
65 – 55 Madry episode of tropical climate
55 – 36 MaHumid climate
+ tectonic activity
36 – 2 Madry climate
Intrusive rock
Souza Silva, Glasmacher et al. 2011
Intrusive rock
Neopr. Fol. graniteIntrusion
Souza Silva, Glasmacher et al. 2011
IntrusionSandstone ~ 150 Ma
Long-term evolution of
Upper Cretaceous
intrusions
~130 Ma
Raab et al. 2005
Fast exhumation between 80 – 60 Ma
- Formation of NE-SW trending small basin (< 1,000 km)
filled by siliciclastic sediments
- Submarine Extrusion of volcanics
RiftRift
Taubaté Basin
Sierra do MarSierra de MantiquerraTaubaté
- Activation of major NW-SE tending faults
with differentiated uplift
- Connected to fracture zones/transfer zones;
transform faults off shore
RiftRift
Cobbold et al.
2001
NE-groupCentral-group
SW-group
13.85 (1.43)
53.46 (2.00)
49.50 (10.35)
13.85 (1.43)
22.88 (1.83)
46.80 (3.95)
49.80 (2.43)
49.16 (3.88)
47.45 (2.72)
Franco, Hackspacher, Glasmacher et al. 2010
~60 Ma
~50 Ma ?
Parana Dacite
At ~50 Ma
~20 Ma
~20 Ma ?
47.67 (10.98)
~60 Ma ?
~40 Ma
>3000 m above
Neoprot. Gra. samples indicate ~ 40 Ma
Elevation difference Dacite – Neoprot. Gra. ~1000 m
Exhumation of 0.1 mm/a
40.23 (4.02)
44.32 (3.73)
~60 Ma ?
Santos Basin
Franco, Hackspacher, Glasmacher et al. 2010
Raab 2001
100 200 300 400 500
- Formation of the recent escarpment (partly < 800 m)
Rift
Sierra do MarSierra de Mantiquerra
Taubaté
Rift
Dynamic topography evolution at the PCM-Brazil + southern Africa:
Deposition of Parana – Etendeka flood volcanics
135 – 80 Ma: Denudation after deposition of flood volcanics Bras
~ 200 km inland, today
- Strange situation in Namibia: flood volcanics at coastal level; no escarpment- Strange situation in Namibia: flood volcanics at coastal level; no escarpment
Activation of Neopro. Shear zones
Brazil: ~ 110 Ma
Namibia: ~70 Ma + ~50 Ma
Dynamic topography evolution at the PCM-Brazil + southern Africa:
Intrusions
80 – 60 Ma: Cooling and Denudation Bras
Namibia: Denudation
Graben system
60 – 30 Ma Evolution of new NE-SW trending graben system with volcanics
Nothing known in Namibia so far
Dynamic topography evolution at the PCM-Brazil + southern Africa:
Fracture zones/transfer zones
60 – 20 Ma Movement along NW-SE trending fault systems
100 – 60 Ma in Namibia
Dynamic topography evolution at the PCM-Brazil + southern Africa:
Escarpment formation
~20 Ma to recent: New excarpment formation and very localized denudation
Namibia: Denudation ?
Platform formation
35 – 0 Ma in Brazil
Namibia ?
Is it the mantle?
Or climate change?
Courtesy of M. Palmer, Oxford University
Thank you for your attention!
Research team:
Jaqueline de Souza Silva (Bachelor/Master student)
Markus Karl (Ph. D. Student)
Peter Hackspacher (cooperation partner Brazil)
Ulrich A. Glasmacher + A. Förster (Project leaders)
Uganda + Congo