Strata2.1 Forward Modeling to learn about the controls of Tectonics, sedimentation and eustasy on stratigraphic geometr

Strata2.1 Forward Modeling to learn about the controls of Tectonics, sedimentation and eustasy on stratigraphic geometry Strata2.1 is Open Source software was written by Flemings, Grotzinger, Morris and Nelson, 1996

Baltimore Canyon Trough • Movie produced by students Spinelli an Hotsinski • http://hydro.geosc.psu.edu/Sed_html/movie1.html Sea-level drops produces major regional unconformity

Mixed Carbonate-clastic systemsMiddle to Late Ordovician, Central Pennsylvania • The following movie was created by Roberta Hotsinski and Andrew Hoover: http://hydro.geosc.psu.edu/Sed_html/movie2.html

Low heat-flux rift basin • http://hydro.geosc.psu.edu/Sed_html/movie4.html Sediment traps heat faster than it can escape (thermal blanket effect)

High sediment-flux rift basin • http://hydro.geosc.psu.edu/Sed_html/movie5.html A thick thermal blanket traps heat in deeper parts of the basin

Near-forebulge stratigraphy • Prediction

Near-forebulge stratigraphy • Prediction Erosion

Near-forebulge stratigraphy • Prediction

Near-forebulge stratigraphy • Strata 2.1

Near-forebulge stratigraphy • Strata 2.1 Erosion

Input parameters in Strata • Sediment types • Compaction and composition • Tectonic styles • Sea-level changes • Heat flow Output data in Strata (versus time) Depth-sections Time-sections Wheeler plots Seismic responses

Sediment Types Clastic sediments Continental diffusion rate pelagic Marine diffusion rate Sediment flux Sedimentation rates

q-volume sediment flux (m^2/s) k- diffusion constant h-elevation x-horizontal distance Continental diffusion rate Values can vary across the model and input in tabular form (x q1; x2 q2; x3 q3 etc.) Sedimentation rates

Sediment Types Carbonate sediments • Sedimentation rate types : simple exponential decay (“epeiric”) • Sedimentation rate types : constant and simple exponential decay below a certain depth (“oceanic”) Sedimentation rates

Input parameters in Strata • Sediment types • Compaction and composition • Tectonic styles • Sea-level changes • Heat flow Output data in Strata (versus time) Depth-sections Time-sections Wheeler plots Seismic responses

Compaction and Composition Porosity versus depth- exponential compaction relation Sand-shale ratios based on water-depth or diffusion constants

Input parameters in Strata • Sediment types • Compaction behavior • Tectonic styles • Sea-level changes • Heat flow Output data in Strata (versus time) Depth-sections Time-sections Wheeler plots Seismic responses

Tectonic styles of subsidence • Subsidence increases linearly left to right (‘foreland’) • Subsidence is constant (flat geometry/’cratonic’) • Subsidence increases linearly right to left (‘passive’) • Simple elastic flexure or local isostasy (Te=0)

Sea-level changes • As a file (all parameters can be entered as such) • As a sinusoid

Heat Flow • mW/m^2 (e.g., 60 for continents) • Thermal conductivity is calculated as a funciton of the sand, shale and fluid content which may be derived from the sedimentation diffusion constants and water depths • Thermal maturation indices can then be calculated • Heat flow is one-dimensional (“hot-to-cold --`down-up”)

Wheeler Plot Erosion sea-level drop time distance

Seismic Responses • Seismic velocity is calculated using the ration of sand, shale and water • Density for sand, shale and fluid is user-input • Seismic sections are displayed

Strata2.1 Forward Modeling to learn about the controls of Tectonics, sedimentation and eustasy on stratigraphic geometr