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