Tectonic heat flow modelling for basin maturation: method and applications

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1 Tectonic heat flow modelling for basin maturation: method and applications J.D. van Wees 1,2, R. Abdul-Fattah 1, D. Bonte 1,2, H. Kombrink 1, H. Verweij 1, F. van Bergen, P. David F. Beekman 2, S. Cloetingh 2 2 Vrije Universiteit Amsterdam 1 TNO

2 Content Definition of tectonic heat flow Workflow Added value of tectonic heat flow Tectonic models for the Netherlands West Netherlands Basin Netherlands Antilles Terschelling Basin Variscan Foreland evolution

3 Heat flow (q) relates to the temperature gradient. Present day (PD) Temperature data ( ) in wells can be directly related to (q) dt dz = q / PD heat flow q=8 q=6 q=4 q=3 k Best fit Depth (z) Temperature (T) sandstone k=2.5 salt k=6 shale k=1.7

4 tectonic heat flow is calculated from the temperature gradient in the top of the numerical kinematic models, which predict temperature effects of lithosphere deformation. The 1D McKenzie Model (1978) is a classic for continental lithosphere extension (rifting) McKenzie model: lithosphere (Li) is instantaneously thinned by factor β Temperature (T) Li Le β =L i /L e crust mantle Depth (z) t=1my t=my t=1my t=3my t=3my 12 km 133 C

5 Sediment record: Burial historyobserved mass deficit Tectonic Subsidence Model (δ = 1.47) Age [Ma] Air loaded tectonic subsidence [m] Observed Model Tectonics: Lithosphere extension Predicted Mass surplus 16

6 For the McKenzie model a very simple analytical solution for the heat flow exist (McKenzie, 1978) 12 Heat flow McKenzie Model (for various β -values) McKenzie heat flow No Good: Heat Flow [mw m-2] No crustal heat production No sediment infill km Age[MA]

7 Water filled 75 7 Basement Heat Flow ( Heat production, β=1.44) no sediments sediments Sediment filled H e a t F l o w [m W m -2 ] synrift Age[Ma] Heat Flow Model, stretching (β=1.44)

8 Van Wees and Beekman, 2 sed Subsidence Inversion tectonic heat flow dt/dz dt/dz crust Tectonic Subsidence curve Lithosphere Parameters Lithospheric thickness Normal geotherm 1/β stretched geotherm crust mantle Inverted Tectonic model TECTONIC HEAT FLOW

9 Subsidence Inversion tectonic heat flow Heat flow Uncertainty SUBmin, PWDmax SUBmax, PWDmax Tectonic Subsidence curve Uncertainty Tectonic Subsidence (PWD/erosion) PWD Sample, interpolate from Experimental nodes Lithosphere Parameters Uncertainty Lithosphere Parameters (crust/lith) End-members Inverted Tectonic model TECTONIC HEAT FLOW Experimental design alternative Inverted Tectonic models MC sampling UNCERTAINTY TECTONIC HEAT FLOW SUBmin, PWDmin SUB SUBmax, PWDmin Experimental design Van Wees et al., 28 Marine and Petroleum Geology

10 Subsidence Inversion tectonic heat flow Tectonic Subsidence curve Heat flow Uncertainty Uncertainty Tectonic Subsidence (PWD/erosion) Maturation Uncertainty Uncertainty Sedimentary Thermal properties Lithosphere Parameters Uncertainty Lithosphere Parameters (crust/lith) End-members Inverted Tectonic model Experimental design alternative Inverted Tectonic models TECTONIC HEAT FLOW MC sampling UNCERTAINTY TECTONIC HEAT FLOW MC sampling Uncertainty Maturation Calibration to Ro PD temperatures sensitivity analysis

11 West Netherlands Basin WAS-2 A priori Uncertainty Lithospheric thickness 9-13 km Erosion during Late Cretaceous Inversion 5-15 m Porosity depth curves sediment conductivity Calibration Ro depth trend PD temperature gradient -

12 Age [Ma] Tectonic subs [m] data model Subsidence NWB 5

A Depth [m] 5 1 15 2 25 3 Temperature[C] 5 1 15 was-32 -observed Model B Depth [m] 15 2 25 3 Ro

13 A Depth [m] Temperature[C] was-32 -observed Model B Depth [m] Ro [%] was-32- observed Model km Lithosphere thickness EROSION 8+-3 m

14 Sensitivity Tornado-plot PD Temperature [C] Lithospheric Thickness Porosity-depth relationship Lithospheric thickness [m] PD Temperature [C] Porosity-depth / subsidence 1.7 Ma [m]

15 Added value of tectonic heat flow modeling 3D Basin Modeling: How to predict heat flow away from wells? Best fit q=3 well Use linear extrapolation? q=3?

16 Netherlands Antilles Heat Flow [mw m-2] DEEP WATER, 38 mw Possibly HC 7&8s wells, NO HC SHALLOW WATER, 28 mw FAST SLOW Age [Ma] Van Wees et al., 28 Marine and Petroleum Geology

17 Added value of tectonic heat flow modeling Basin Modeling: How to find heat flow in the past Age (Ma) Present day (PD) heat flow Typical start: Flat heat flow through time using the same as PD heat flow Heat Flow

18 Added value of tectonic heat flow modeling Basin Modeling: How to find better heat flow in the past Age (Ma) Modified to fit Ro Heat Flow

19 Seismic tomography demonstrates mantle plumes acting as heat advection channels in the deep lithosphere Ritter et al., 21 Goes et al., 2

20 dt/dz Extension models melts and underplates can arise from hot mantle (plumes) which result in accentuated heat advection and heat flow, relative to default extension dt/dz Crust Normal geotherm stretched geotherm Underplate Mantle

21 dt/dz dt/dz dt/dz Crust Mantle uniform two-layered δ=1.5 β=3 β=1.5 Hot mantle plume stretched geotherm stretched geotherm Normal geotherm Lithospheric thickness Van Wees et al., 2- Marine and Petroleum Geology Ziegler et al., Tectonophysics

22 Sirt Basin Abadi et al., 28 AAPG Bulletin

23 EAST SIRT- Agedabia WEST SIRT- Hun 1 8 Age [Ma] Age [Ma] data model data model Tectonic subs [m] 5 1 synrift synrift 55 Tectonic subs [m] 5 1 synrift underplating Ro [%] Tem perature [C] Depth [m] Agedabia-obs Agedabia-model HUN HUN-obs 25 HUN-model 3 35 Agedabia 4 45 Depth [m ] BHT 25/km BHT 22/km 5 45

24 Basement heat flow [mw/m2] uniform two-layered dt/dz dt/dz West Netherlands Basin Crust δ=1.5 β=3 β=1.5 Mantle Hot mantle plume stretched geotherm stretched geotherm 65 Age [Ma] Tectonic subsidence [m] 49 observed modelled default heat flow elevated Van Wees et al., 28 Marine and Petroleum Geology dt/dz Normal geotherm Lithospheric thickness

25 Model building: Boundary conditions Tectonic subsidence [m] Age [Ma] Tectonic Sub Tectonic Model -14 Calibrated Heat Flow Basement heat flow [mw/m2] 33 heat flow maps Basal heat flow history reconstructed from tectonic modelling (Petroprob) (Rader Abdul Fattah et al 28)

26 Ziegler et al., 1998 Willingshofer and Cloetingh, Tectonics 22, 23

27 Carboniferous Netherlands (1) Kombrink et al., 28 (Basin Research)

28 Carboniferous Netherlands (2)

29 Carboniferous Netherlands (4)

30 Conclusions Tectonic heat flow models aid in predicting heat flow for basin modelling beyond well control Mature basins - Heat flow through time Frontier basins spatial variability Tectonic heat flow models should include effects of crustal heat production and sediment infill/erosion The Netherlands Average heat flow values today Considerable variation through time: Elevated at mantle plume/underplating phase Depressed during foreland formation

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