István Dunkl Sedimentology, University of Göttingen

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1 Beckenanalyse 2: Analytic tools for basin analysis: thermometers and geochronometers [M.Geo.136b] Part 5: FT Reconstruction of thermal evolution of basins University of Göttingen István Dunkl Sedimentology, University of Göttingen 1) Heat flow in basins 2) Geothermometry in basins by: vitrinite-, bitumen-, graptolite reflectance, Raman spectroscopy, conodont alteration index, spore colour, fluorescence, Rock-Eval, molecular ratios, clay mineralogy... 3) Fission track thermochronology (nuclear physics, statistics) 4) Dating volcanic events (= formation ages) and basement exhumation (= cooling ages) 5) Complex thermal histories of basins & thermal modelling 6) Detrital geochronology (provenance by single-grain ages) 7) (U-Th)/He thermochronology 8) K/Ar, Ar/Ar, Luminescence, ESR and cosmogenic dating of sediments 9) U-Pb and U-series dating of sediments The principal types of thermal histories time today track stability zone partial anneling zone (PAZ) track instability temperature ~60 C ~120 C FORMATION AGE COOLING AGE MIXED AGE fission track age [Wagner, 1979]

2 Track shortening Track shortening on an Arrhenius diagram Arrhenius, Svante August

3 Confined horizontal tracks are developing below the surface along tracks and clevages [Crowley, 1989] [GÖochronology] Measurement of track length (on horizontal confined fission tracks) transmitted light reflected light [GÖochronology]

4 Relation of thermal history and track length distribution [after Sanders, 1998] Thermal history in basin evolution and track length distribution [Gallagher et al., 1998]

5 Fission track dating: track length distribution Æ cooling history [Anna K. Ksienzyk] Modelling major decisions Forward inverse modelling Supervised - unsupervised Input data Initial conditions Selection of model (algorithm, parameters) Modelling (black box) Test of results

6 Principle of the computation of track length distribution

Result of an unsupervised thermal modeling Malé Karpaty Temperature [ C] 40 80 120 160

7 Result of an unsupervised thermal modeling Malé Karpaty Temperature [ C] Known rifting event (elevated heat flow) Age [Ma] [Danisik et al., in press]

8 Thermal modeling must be preluded by a review of geological events and their thermal consequences. Temperature These dates can be the turning points of the thermal history and thus the timetemperature constraints of the modeling. [Glasmacher et al. 2002] Temperature Now Surface Surface tt2 Surface tt2 tt2 tt3 tt3 Tmax tt1 tt1 tt1 Time [Ma] Time [Ma] Time [Ma] tt1 = age and temperature of metamorphism tt1 = age and temperature of metamorphism Tmax = maximum temperature during burial tt2 = 0 Ma; recent annual mean temperature tt2 = age of sedimentation; annual mean temperature tt3 = 0 Ma; recent annual mean temperature tt1 invariable points best tt path tt envelope effective post-depositional heating [Dunkl and Frisch, 2002]

9 Thermal history of accreting sediments

?) sedimentary succession present temperature 40 Temperature [ C] 80 120 160 unsupervised search 200 50 40 30 20 10 0

10 { Geological constraints for thermal modelling of the evolution of the Carpathian flysch belt 0 age of sedimentation burial below known(!?) sedimentary succession present temperature 40 Temperature [ C] unsupervised search Age [Ma] [Botor et al. in prep.] Results of modelling the thermal histories of the major Carpathian nappes (AFTSolve, Ketcham, 2000). Dominant and common is an extremely rapid warming up period. Magura Dukla Silesian Time [Ma]

sedimentation of volcanic tuff termination of sedimentation by thrusting detachment and accretion

11 Simplified model of thermal history of the Silesian Unit Major periods sedimentary burial tectonic burial exhumation by folding and erosion 0 { { { Temperature [ C] sedimentation of volcanic tuff termination of sedimentation by thrusting detachment and accretion Age [Ma] 10 Thermal history of Silesian nappe 0 Accretional evolution of the Outhern Western Carpathians

C/km Closure temperature: 145 (135-150) C Angle of subduction: 23 (22-25) Time lag between overthrust and

12 Normal faults are also common in the Carpathian thrust pile [Oszczypko-Clowes and Oszczypko 2004] Seismic profile Katowice - Budapest V subduction [Tomek and PANCARDI Team] V=(T Geothermal gradient: 20 (18-25) C/km Closure temperature: 145 ( ) C Angle of subduction: 23 (22-25) Time lag between overthrust and reset: 2 ( ) Ma closure /gg)*ctg(alpha)/time O-R Horizontal speed of subduction: ~8.8 ( ) km/ma [Botor]

Thermal histories of two, neighbouring metamorphite bodies Deposition of Mesozoic sediments on Wechsel unit Thrusting Eocene sedimentation Miocene extension and sedimentation Temperarture [ C] 100

Cretaceous Paleoc. Eocene Olig. Miocene Pli. 80 70 60 50 40 30 20 10 0 Ma Major events Cooling after Eoalpine metamorphism Gosau sed.

13 Thermal histories of two, neighbouring metamorphite bodies Deposition of Mesozoic sediments on Wechsel unit Thrusting Eocene sedimentation Miocene extension and sedimentation Temperarture [ C] apatite PAZ zircon PAZ wh. mica K/Ar T i m e [m i l l i o n y e a r s] Wechsel unit Grobgneis unit at the northern margin of the Wechsel Window Thermochronology -> exhumation ->?relief? Cretaceous Paleoc. Eocene Olig. Miocene Pli Ma Major events Cooling after Eoalpine metamorphism Gosau sed. Post-Gosau compression Reef, red clay, peneplain Major subsicdence in intramontane basins Periadriatic magmatism Main trends in exhumation & subsidence exh. subs. Gosau basins? Relief Mountainous Hills-lowlands Sedimentation + ++?? ridges basins * ** Austroalpine crystalline Austroalpine crystalline (in the north, where Cretaceous apatite FT ages preserved Austroalpine crystalline (in the south, where Oligocene apatite FT ages are common Austroalpine Paleozoic metasediments and post-variscan cover [Dunkl et al., unpublished]

16090 Reset of apatite FT ages during burial Apatite fission track age [Ma] 70 60 50 40 30 20 10 0 0 10 20 30 40 50 60 70 Stratigraphic age [Ma] 1:1 Confrontation of burial

14 16090 Reset of apatite FT ages during burial Apatite fission track age [Ma] Stratigraphic age [Ma] 1:1 Confrontation of burial history and apatite FT reset Temperature [ C] Oligocene sandstone 796 m 42 C predicted modeled Ma the Puszta in winter-time

Trend in reset 70 65-85 Ma: typical Eoalpine cooling ages and unreset ages in the sediments 60 Region A Apatite FT

Pannonian basin isotherms tilted seismic reflectors Carpathians uplifted sediment remnants Mesozoic Exhumation:

in heat-flow time depth PAZ mica Ar reset depth zero zircon FT age - Late Cretaceous (~80 Ma), - Miocene (18-10

15 Trend in reset Ma: typical Eoalpine cooling ages and unreset ages in the sediments 60 Region A Apatite FT age [Ma] 50 Region B Temperature [ C] Neogene sites of delayed FT reset Pannonian basin isotherms tilted seismic reflectors Carpathians uplifted sediment remnants Mesozoic Exhumation: 2-4 Ma (young infiltration of karst water) Elevated isotherms Reset of the FT thermochronometer Exhumation Change in heat-flow time depth PAZ mica Ar reset depth zero zircon FT age - Late Cretaceous (~80 Ma), - Miocene (18-10 Ma) - Permian (~250 Ma), - Late Triassic (~220 Ma), - Jurassic ( Ma), - Oligocene (~30 Ma), - Pliocene-Quat. (4-2 Ma)

Thermochronologic assessment of a hydrocarbon play

maturation Recent Schöckl WSW 50 km E a s t e r n

Middle Miocene Dinarids Rechnitz Window Penninic

Vertical movement since Middle Miocene: Uplift

sediments Early-Middle Miocene normal faults

Penninic Hanging wall and sediment remnants on top

16 Thermochronologic assessment of a hydrocarbon play Joint modelling of thermochronology and organic maturation Recent Schöckl WSW 50 km E a s t e r n A l p s Rechnitz Window X Pannonian basin Danube basin ENE km Tauern W. Eastern Alps Carpathians Pannonian basin 200 km Middle Miocene Dinarids Rechnitz Window Penninic windows? Vertical movement since Middle Miocene: Uplift Subsidence X Post-rift sediments Syn-rift sediments Early-Middle Miocene normal faults Austroalpine Paleozoic Austroalpine basement Penninic Hanging wall and sediment remnants on top of the Penninic window (sample sites) A hanging wall footwall B WSW ENE Sample site Modeled heat flow of this section is in Figure 10

17 Modelling of vitrinite reflectance Ottnangian Karpatian Badenian Sarmatian Pannonian 2 90 mw/m (initial value) mw/m (during fast faulting) mw/m (post-rift to recent) Ma Heat flux history Variables: - heat flux - burial Beginning of sedimentation Subsidence history Output: - coal rank Known erosional periods "Styrian" "Sarmatian-Pannonian" "Pliocene" Reconstruction of paleo-burial Heat flow [mw/m 2 ] Range of the heat flow in the hangingwall Range of the necessary burial for the observed vitrinite reflectance Burial thickness [m] Vitrinite reflectance (%) Coal rank of the Sinnersdorf beds [Dunkl et al., 1998]

18 Basin inversion: estimation of the removed section [Japsen et al., 2007] Reconstructed burial-exhumation history (note the Late-Paleogene surface temperature drop) [Japsen et al., 2007]

Reconstruction of the inverted part of the North Sea [Japsen et al.

of simulated vitrinite reflectance and fission track age and

m. GOF denotes value of the fit statistic; a value of 1 is a

19 Reconstruction of the inverted part of the North Sea [Japsen et al., 2007] Estimation of the eroded thickness by modelling Response of simulated vitrinite reflectance and fission track age and length data to Late Cretaceous exhumation of (a) 250 and (b) 1000 m. GOF denotes value of the fit statistic; a value of 1 is a perfect fit of the simulated and the observed data. [Luijendijk et al., 2011]

, 2011] Questions Why do we measure track lengths?

20 Estimation of the eroded thickness by modelling Model fit statistics of all Late Cretaceous exhumation and basal heat flow model scenarios. [Luijendijk et al., 2011] Questions Why do we measure track lengths? Which are the input and output parameters of the thermal modelling? What geological facts should we consider at thermal modelling? What is the measure of the reality of the modelling results?

Low-Temperature Geothermometry and Geochronology in Basis Analysis Part 4: Reconstruction of thermal histories of basins

Low-Temperature Geothermometry and Geochronology in Basis Analysis Part 4: Reconstruction of thermal histories of basins István Dunkl Sedimentology, University of Göttingen http://www.sediment.uni-goettingen.de/staff/dunkl/