COMPARISON OF TWO-DIMENSIONAL MODELS -- COPROD2 COPROD2 data set information, Vers. 1.4 3 September 1993. This dataset of MT (RXY & RYX) & GDS (TZY) responses is for distribution to scientists wishing to test out their 2D modelling procedures. This disk (or COPROD2 subdirectory) should contain the following 38 files:- README this information pc5000c.dat to 35 sites of data pcse04c.dat coprod2.prf profile locations (as below) The MT data have already been corrected for "static shift" (see Jones, 1988). The uncorrected data are also available on request if you consider that your inversion method can handle static shifts - however for consistency in any "final" publication comparing inversion methods only the models from the static corrected data will be taken. The full dataset consists of thirty-five (35) sites over a 407 km traverse with forty (40) responses in the range 384 Hz to 1820 s. RXY are the TE-mode (E-polarization) responses, whereas RYX denotes the TM-mode (B-polarization) ones. The GDS data are the TE-mode responses only (TZY). The profile is across the Phanerozoic Williston Basin, and there are anomalies in the data which you are to locate. Some information is given in Jones and Savage (1986). My models of the data are given in Jones and Craven (1989) - however, you should try to invert the data without reference to my models! The locations of the stations (in kilometers east of Macoun in Saskatchewan, which is at 103:15:34.5 West; which is 18.87 km WEST of 103 West) are:- PC5000S 232800 PC5001S 214600 PC5002S 194100 PC5003S 181200 PC5004S 169400 PC5005S 155200 PC5006S 135300 PC5007S 117300 PC5008S 96200 PC5009S 79500 PC5010S 64200 PC5011S 54500 PC5012S 41800 PC5013S 22800 PC5014S 4900 PCSE04S -5900 PCSE03S -14600 PCSE02S -25900 PCSE01S -35000 PCS001S -45800 PCS002S -55700 PCS003S -64900 PCS305S -69100 PCS004S -74400 PCS405S -78800 PCS005S -84600 PCS006S -93000 PCS007S -100900 PCS008S -113500 PCS009S -124200 PCS010S -133500 PCS011S -143300 PCS012S -154500 PCS013S -161800 PCS014S -174300 Some comments on the data: a) If a value is set to -999, then no value exists for that response at that period. b) If a resistivity is set to a negative value, then I have judged it to be too scattered (i.e., too biased) from its neighbours for the error level associated with it. You can ignore this value or reset it to positive to include it in your inversions. c) Note: the XY responses are the E-polarization or TE mode, with phases in the range 0 - 90 degrees (first quadrant). The YX responses are the B-polarization or TM mode, with phases in the range -180 - -90 degrees (third quadrant). A "reduced" dataset is defined - named COPROD2R - which is the responses from 20 sites at 4 periods. This is to aid those who are unable to handle the full dataset and want to concentrate their CPU cycles on the anomalous observations above the NACP rather than the more smoothly varying higher frequency and off-anomaly responses and responses sensitive to the TOBE anomaly (see Jones and Savage 1986). This reduced dataset is from the following sites: PCS008 -113500 PCS007 -100900 PCS006 -93000 PCS005 -84600 PCS004 -74400 PCS003 -64900 PCS002 -55700 PCS001 -45800 PCSE01 -35000 PCSE02 -25900 PCSE03 -14600 PCSE04 -5900 PC5014 4900 PC5013 22800 PC5012 41800 PC5011 54500 PC5010 64200 PC5009 79500 PC5008 96200 PC5007 117300 At the following four periods: 85.33, 170.7, 341.3, 682.7 You may work with these data provided that you observe the following caveats. 1) In the acknowledgements in any publication, you acknowledge P.J. Savage of PanCanadian Petroleum Limited of Calgary, Alberta, for making the raw (uncorrected) data available to the GSC. 2) Please do not give these data on to anyone. I would prefer that all participants of COPROD2 get the data from me so that everybody has the same data - I know how easy it is to "edit" data then forget you have done so, then pass it on to somebody else as the kosher COPROD2 dataset (this occurred frequently with the COPROD1 dataset). 3) Keep me informed of your results - I hope to write a comparative paper in a few years time (something I kept meaning to do for COPROD1) with every participant as a co-author. Especially I would like preprints/reprints/reports etc. of any manuscript that uses these data. Notes: 16-AUG-1989: Some of the weights for the TZY data are greater than 1, and some are even too large for the format used and appear as *****. Please ignore these weights. 03-SEP-1993: The original uncorrected data are available on application to me for testing static shift correction methods. GOOD LUCK! Alan G. Jones Geological Survey of Canada 1 Observatory Crescent OTTAWA, Ontario Canada, K1A 0Y3 tel: (613) 992-4968 FAX: (613) 992-8836 email: ajones@nrcan.gc.ca References ========== Jones, A.G., 1988. Static shift of magnetotelluric data and its removal in a sedimentary basin environment. Geophysics, vol. 53, pp. 967-978. Jones, A.G. and Craven, J.A., 1990. The North American Central Plains conductivity anomaly and its correlation with gravity, magnetics, seismic, and heat flow data in the Province of Saskatchewan. Phys. Earth Planet. Inter., vol. 60,pp. 169-194. (preprint available on request) Jones, A.G. and Savage, J.G., 1986. North American Central Plains anomaly goes east. Geophysical Research Lett., vol. 13, pp. 685-688. see also: Jones, A.G., 1988. Discussion of "A magnetotelluric investigation under the Williston Basin" by J.M. Maidens and K.V.\ Paulson. Can. J. Earth Sci., vol. 25, pp. 1132-1139.