Three-dimensional basin analysis of theHeidelberg Basin, Upper Rhine Graben

David C. Tanner, Nicole Martini, Hermann Buness, Gerald Gabriel, Charlotte M. Krawczyk

0 km 30

Leibniz Institute for Applied Geophysics

Contents

LocationNew and old reflection seismics of the Heidelberg BasinStratigraphy3D Geometrical Model (GoCAD)Decompaction and Subsidence Analysis (3Dmove)Conclusions

Location / Database

0 1 km

Quarternary thickness in the URG after Bartz 1974

Location of reflection seismics in theHeidelberg Basin

Borehole A

Uni Nord

StratigraphyBorehole A

Base Quaternary

Base Pliocene

Base Upper Miocene

Base Hydrobien beds (Lower Miocene)

Internal Pliocene

Reflection Seismics

LIAG P-wave profile 3, Heidelberg, Depth section (Buness et al., 2008)

N S

1000

500

0

1500

Dep

th(m

)

Base Quarternary

Internal PlioceneBase Pliocene

Base Upper Miocene

Base Hydrobrien beds

3

MethodCorrelation

digitized withtif2segy

Seismic Borehole

InterpretedSeismics (Time)

Coordinates

Depths of beds

Conversion

withPromax2D Interpreted

Seismics (Depth)

LIAG Industry

correlation withgeog. coordinates

2D Model

3D Model

Interpretion

picked by hand

digital

Depth surfaces - Depocentre

Base Quaternary3471000 3473000 3475000 3477000

5470000

5471000

5472000

5473000

5474000

5475000

5476000

5477000

5478000

5479000

5480000

Internal Pliocene3471000 3473000 3475000 3477000

5470000

5471000

5472000

5473000

5474000

5475000

5476000

5477000

5478000

5479000

5480000

Base Pliocene3471000 3473000 3475000 3477000

5470000

5471000

5472000

5473000

5474000

5475000

5476000

5477000

5478000

5479000

5480000

Base Upper Miocene3471000 3473000 3475000 3477000

5470000

5471000

5472000

5473000

5474000

5475000

5476000

5477000

5478000

5479000

5480000

Base Hydrobien beds3471000 3473000 3475000 3477000

5470000

5471000

5472000

5473000

5474000

5475000

5476000

5477000

5478000

5479000

5480000

-2100-2000-1900-1800-1700-1600-1500-1400-1300-1200-1100-1000-900-800-700-600-500-400-300-200-100

Depth (m]

Method of Correlating Seismics• Problem: No connection between LIAG (red) and industry (blue) seismic lines

• Solution: Strike projection

0 1

Schriêsheim

Uni Nord

Stereographic projection

averagestrike direction

32

8101 8306

Method of Gridding Surfaces• Original data

• Seismic interpretation @ every 10th CMP

• ca. 900 points per surface

• Data were gridded using Discrete Point Interpolation (GOCAD) and the Point Krigingalgorithm (Surfer)

• Output grid with X Y spacing of 100 m.

N

Difference between DSI and Kriging(e.g. Base Quaternary)

3D Model

GoCAD model,5x vertical exaggeration

1 kmBase Quarternary

Base Pliocene

Base UpperMiocene

Base HydrobienBeds (Miocene)

Calculation of Porosity

Core sample

Water-saturated Sample

Saturated Mass

Dry Mass

Submerged Mass

Calculation of Porosity

Rock Volume

Dry Mass

Volume of absorbed water

Porosity

Saturation in water (24h)

Drying (48-72h) at 130°C

Dry Sample

Porosity change with depth

Athy, 1930

Silt Fine Sand Medium Sand

Uni Nord borehole

Decompaction and Backstripping I

Decompaction and Backstripping II

Subsidence

A. Western edge of model, towards graben centre

B. Depocentre of the Heidelberg Basin

Dep

th(m

)Time (Ma) Time (Ma)

0.05 mm/a

0.1 mm

/a

0.1 mm/a

0.2 mm

/a

Conclusions

1. We interpreted reflection seismics to produce a 3D model of the Heidelberg Basin, with 5 stratigraphic horizons.

2. The model shows the depth of the (mini) basin, and movement of the depocentre.

3. We suggest that the basin is pull-apart basin, centered on a „breached“ relay zone.

4. The porosity of the Quaternary sediments decreases exponentiallywith depth. We used this information to incrementally decompact the Heidelberg Basin, to examine the true changes in basin morphology.

5. Subsidence of the Heidelberg Basin was fast (twice as fast as the average in the URG); average rates are 0.1 mm a-1 and rise to 0.2 mm a-1 during the Quaternary.

References

Tanner, D.C., Martini, N., Buness, H., Gabriel, G. & Krawczyk, C.M. (2010). Three-dimensionalbasin analysis of the Heidelberg Basin, Upper Rhine Graben. GeoDarmstadt 10-13th October2010. Schriftenreihe der Deutschen Gesellschaft für Geowissenschaften 68, 548-549.Tanner, D.C., Martini, N., Buness, H., Gabriel, G. & Krawczyk, C.M. (2010). The Heidelberg BasinDrilling Project - basin analysis. European Geosciences Union General Assembly, Vienna 2nd-7th May 2010.Athy, L.F. (1930) Density, Porosity and Compaction of Sedimentary Rocks. AAPG Bulletin Volume14: 1–24.Buness, H., Gabriel, G. & Ellwanger, D. (2008) The Heidelberg Basin drilling project: Geophysicalpre-site surveys. Quaternary Science Journal (Eiszeit und Gegenwart) 2008, 57/3–4: 338-366.Ellwanger, D., Gabriel, G., Hoselmann, C., Lämmermann-Barthel, J., Weidenfeller, M. (2005) TheHeidelberg Drilling Project (Upper Rhine Graben, Germany). Quarternaire 2005, 16/3: 191–199.Martini, N. (2009) 3D-Modellierung im Umfeld des Heidelberger Beckens. Diplomkartierung, Universität Hannover, 23 S., unveröffentlichtMartini, N. (2010) Retrodeformation des Heidelberger Beckens. Diplomarbeit, Universität Hannover, 88 S., unveröffentlicht