DSX-08 Saariselka June 8-13, 2008 IMAGING & INTERPRETING CONTINENTAL LOWER CRUST: FROM POTENTIAL PROBLEMS TO PROBABLE PROCESSES Kabir Roy-Chowdhury Utrecht University, The Netherlands
KRC, Department of Earth Sciences DSX-08: Saariselka, June 8-13, 2008 Imaging & Interpreting CLCDeterministic Probabilistic Fellow Travellers Quarry Blasters at Univ Hamburg: Menzel The Instt. Of Geophysics, Kiev The DSS group at N.G.R.I. Hyderabad Geo-Sciences, Princeton: Phinney, Kong, Hansen Geo-Sciences, Utrecht: Douma, Carpentier Levander, Hurich, Holliger and many others … And also Geologists like Smithson, Rutter, …
KRC, Department of Earth Sciences DSX-08: Saariselka, June 8-13, 2008 Imaging & Interpreting CLCDeterministic Probabilistic Late ’60s – early ’70s Recording quarry blasts with MARS recorders Sporadic locations with m Phase correlations of refracted arrivals Modelling (scattered) wave-forms from MOHO Transition zone? Linear gradient? Lamellae?
KRC, Department of Earth Sciences DSX-08: Saariselka, June 8-13, 2008 Imaging & Interpreting CLCDeterministic Probabilistic Indo – Soviet collaboration (1972 -) Kiev group had contoured Moho below Ukraine! 660 km Kavali – Udipi profile in Indian Shield Kg source, 100 m spacing, analogue rec Human-intensive processing …
KRC, Department of Earth Sciences DSX-08: Saariselka, June 8-13, 2008 Imaging & Interpreting CLCDeterministic Probabilistic Processing DSS records
KRC, Department of Earth Sciences DSX-08: Saariselka, June 8-13, 2008 Imaging & Interpreting CLCDeterministic Probabilistic Indo – Soviet collaboration (1972 -) Kiev group had contoured Moho below Ukraine! 660 km Kavali – Udipi profile in Indian Shield Kg source, 100 m spacing, analogue rec Human-intensive processing Reciprocal (Deep) Reflection Segments Helped First Danger Signals for Interpretation Vertical vs.Horizontal Tectonics …
KRC, Department of Earth Sciences DSX-08: Saariselka, June 8-13, 2008 Imaging & Interpreting CLCDeterministic Probabilistic Gibbs, 1986
KRC, Department of Earth Sciences DSX-08: Saariselka, June 8-13, 2008 Imaging & Interpreting CLCDeterministic Probabilistic 1980s: CERP at Princeton Try to Objectivise the Ubiquitous Line-Drawing Coherency Filter (Kong et al, 1985) …
KRC, Department of Earth Sciences DSX-08: Saariselka, June 8-13, 2008 Imaging & Interpreting CLCDeterministic Probabilistic Kong et al, 1985
KRC, Department of Earth Sciences DSX-08: Saariselka, June 8-13, 2008 Imaging & Interpreting CLCDeterministic Probabilistic 1980s: CERP at Princeton Objectivise the Ubiquitous Line-Drawing Coherency Filter (Kong et al, 1985) … The USGS Long-Island line as a benchmark …
KRC, Department of Earth Sciences DSX-08: Saariselka, June 8-13, 2008 Imaging & Interpreting CLCDeterministic Probabilistic Phinney & Roy-Chowdhury, 1989
KRC, Department of Earth Sciences DSX-08: Saariselka, June 8-13, 2008 Imaging & Interpreting CLCDeterministic Probabilistic COCORP Georgia Lines 1 (above) and 5 (below) Phinney & Roy-Chowdhury, 1989
KRC, Department of Earth Sciences DSX-08: Saariselka, June 8-13, 2008 Imaging & Interpreting CLCDeterministic Probabilistic 1980s: CERP at Princeton Objectivise the Ubiquitous Line-Drawing Coherency Filter (Kong et al, 1985) … The USGS Long-Island line as a benchmark … Sign Filter (Hansen et al, 1988) …
KRC, Department of Earth Sciences DSX-08: Saariselka, June 8-13, 2008 Imaging & Interpreting CLCDeterministic Probabilistic Hansen et al, 1988
KRC, Department of Earth Sciences DSX-08: Saariselka, June 8-13, 2008 Imaging & Interpreting CLCDeterministic Probabilistic 1980s: CERP at Princeton Objectivise the Ubiquitous Line-Drawing Coherency Filter (Kong et al, 1985) … The USGS Long-Island line as a benchmark … Sign Filter (Hansen et al, 1988) … Second Danger Signal for interpretation Look beyond Phase … to Amplitudes too Black/White problem (Seismix88 in Canberra)
KRC, Department of Earth Sciences DSX-08: Saariselka, June 8-13, 2008 Imaging & Interpreting CLCDeterministic Probabilistic Enigma of Lower Crustal Reflectivity Exposures exhibit multi-scale structure Compositional and Evolutionary causes Banded reflectivity at mid/lower- crustal depths Compute Response of a Random Bi-modal Stack Vertical Reflection Coefficient could be ~ 0.7! Classify Regions based upon Back-Scattering Roy-Chowdhury et al, 1988
KRC, Department of Earth Sciences DSX-08: Saariselka, June 8-13, 2008 Imaging & Interpreting CLCDeterministic Probabilistic 1990s: let’s go stochastic An explosion of people and papers Random Layering gives Banded Reflectivity Crustal Exposures show von Karman structure Difficult to estimate the relevant parameters Quantitative? Interpretation of Deep Seismic Data Gibson, Holliger, Hurich, Levander, Pullammanappallil, …
KRC, Department of Earth Sciences DSX-08: Saariselka, June 8-13, 2008 Imaging & Interpreting CLCDeterministic Probabilistic Picking up the thread again Multiple Scattering in a Multi-Scale Medium Layer-Cake model with von Karman structure Bi-modal material property (impedance) Vertical Incidence of P-waves (no conversions) Can Single-Scattering based Processing work?
KRC, Department of Earth Sciences DSX-08: Saariselka, June 8-13, 2008 Imaging & Interpreting CLCDeterministic Probabilistic Douma & Roy-Chowdhury, 2001
KRC, Department of Earth Sciences DSX-08: Saariselka, June 8-13, 2008 Imaging & Interpreting CLCDeterministic Probabilistic The Estimation Problem 2-D von Karman Medium with a x, a z and Bi-Modal Lithology (back to the BW problem) Full-wave seismic response is von Karman too Medium parameters may be back-estimated Carpentier and Roy-Chowdhury
KRC, Department of Earth Sciences DSX-08: Saariselka, June 8-13, 2008 Imaging & Interpreting CLCDeterministic Probabilistic The (under)Estimation Problem Getting Reflectivity from Impedance lowers a x Estimated a x may be upscaled, is less robust Source deconvolution needed to estimate a z Dip Scan improves Estimation for Rotated Blocks Carpentier and Roy-Chowdhury
KRC, Department of Earth Sciences DSX-08: Saariselka, June 8-13, 2008 Imaging & Interpreting CLCDeterministic Probabilistic Carpentier et al Dip Scan using a Data- window from the Lithoprobe AG-48 line improves the estimation
KRC, Department of Earth Sciences DSX-08: Saariselka, June 8-13, 2008 Imaging & Interpreting CLCDeterministic Probabilistic Got Curious? Visit our Poster (# 72) Method tried on two Deep Reflection Datasets Lithoprobe Abitibi-Grenville (AG-48) line DOBRE 2000/2001 lines in Ukraine! (world is round!) Results similar to earlier Interpretations Some interesting differences though Should help constrain Tectono-Thermal History Thanks!
KRC, Department of Earth Sciences DSX-08: Saariselka, June 8-13, 2008 Imaging & Interpreting CLCDeterministic Probabilistic Carpentier et al AG-48
KRC, Department of Earth Sciences DSX-08: Saariselka, June 8-13, 2008 Imaging & Interpreting CLCDeterministic Probabilistic Carpentier et al AG-48
KRC, Department of Earth Sciences DSX-08: Saariselka, June 8-13, 2008 Imaging & Interpreting CLCDeterministic Probabilistic Carpentier et al AG-48
KRC, Department of Earth Sciences DSX-08: Saariselka, June 8-13, 2008 Imaging & Interpreting CLCDeterministic Probabilistic Carpentier et al AG-48
KRC, Department of Earth Sciences DSX-08: Saariselka, June 8-13, 2008 Imaging & Interpreting CLCDeterministic Probabilistic Carpentier et al DOBRE 2000/1
KRC, Department of Earth Sciences DSX-08: Saariselka, June 8-13, 2008 Imaging & Interpreting CLCDeterministic Probabilistic Carpentier et al DOBRE 2000/1
KRC, Department of Earth Sciences DSX-08: Saariselka, June 8-13, 2008 Imaging & Interpreting CLCDeterministic Probabilistic Carpentier et al DOBRE 2000/1
KRC, Department of Earth Sciences DSX-08: Saariselka, June 8-13, 2008 Imaging & Interpreting CLCDeterministic Probabilistic Carpentier et al DOBRE 2000/1