1 Geology 409: Applied Geophysics Laboratory 12 hours lectures ...

Evaluation:15% Written lab reports on field testing of geophysical instruments in City Park.10% Written proposal for field work at Calabogie and Admaston field sites.10% Oral debriefing following the field trip.50% Final fieldwork reports.15% Petroleum exploration (seismic interpretation) exercise.Reporting1. Individual reports on field testing of instruments (5% per report, three in total)The objective is produce a report on the proper functioning of each instrument, and to makerecommendations for field procedures to be used during the Calabogie and Admaston field trip. The fieldtest data should be quantitatively compared with expected geology and anomalies in the area to documentthe correct instrument response. Reports on the following instruments are required:Week 1: Gravity: Scintrex CG-2 (Worden Gravity meter)Magnetics: Scintrex IGS-2 (Proton Precession Magnetometer)GSM-19TW (“Walking” Proton Precession Magnetometer)Week 2: IP/Resitivity: Iris Instruments SYSCAL Junior Resistivity/IP meter.EM: Geonics EM-31, APEX Max-Min IIWeek 3: Seismic: Geometrics R24 Strataview 24-channel seismographRadar: Sensors and Software pulseEKKO 100 MHz GPRStudents must submit each weekly report before they will be permitted to participate in the next week’sfield test exercise. These reports are to be written individually, although collaboration with base maps anddata plotting is encouraged. The field tests carried out in City Park of the geophysical instruments must befully documented, all data must be reduced and quantitative interpretations and/or conclusions mustaccompany the reports. A brief discussion of the instruments used (name and model), where and why theexercise was done, and how the data were collected is required. Conclusions should be written with regardto the functioning of the instrument and any recommended field procedures to be used.Field test reports are to be approximately 750 words per instrument used. Excessive length will bepenalized! The field data should be clearly represented in the form of graphs, figures or tables, asappropriate. Base maps should clearly show the location of each survey, and of any anomalies located.A suggested format for the field test reports is:Objectives: Discussion of where and why survey was performedInstruments: Instruments used, operating principles and what exactly is measured (be brief)Procedure: Brief review of survey procedure (specific to each geophysical method), including setupResults: Brief discussion of results, addressing sources and magnitude of errors and limitationsData analysis and interpretation: This is where you describe what you think your data mean (refer backto the objectives)Conclusions and recommendations: I don’t mind if this is very brief, but it must be suitableBibliography: Include a correctly formatted reference to the manual, and any other material you used.2

TO: All members of Geology 409FROM: Gerhard Pratt, Alan Baird, Rob RenaudDATE: Sept 14 th , 2004Request for proposalsWe would like to receive proposals for geophysical field work at two survey sites in Southern Ontario,within the Grenville Geological Province. The two sites are located i) at Admaston, near Renfrew and ii)near Calabogie, in Lanark County. A total of five days (Oct 10 th - 16 th , 2006) are available; we expect youwill spend approximately equal time at both sites.Admaston SiteThis site is located within the Bonnechere River Valley. The site is topographically very flat and there isgood access by road. The top 50 - 100 m of overburden at this site contain Pleistocene marine clays. Theclays overlie Ordivician limestone bedrock of shallow dip. We would like to receive proposals from youfor mapping a short (300 m) section of the clay-limestone interface. We are also interested in obtaininginformation on any sedimentary structures (layering) within the clay and within the limestones.Previous work at the site has shown that the seismic refraction and reflection methods are able to locateand map the topography of the bedrock; we challenge you to provide us with high quality seismic images.We are also interested in the use of electrical resistivity, and time-domain EM methods in depth sounding.Calabogie SiteThe Calabogie field site was originally mapped out by Geoterrex-Dighem following the detection of ananomaly during an aeromagnetic survey. The was purchased and gridded by Geoterrex for potentialexploration. The site is located south of Calabogie in Darling Township, Lanark County. The site isaccessible via a logging road, but access to the grid is on foot only. The topography is rugged and the areais densely wooded. There is an existing grid staked out at the site, but some time should be allowed forbrush clearing and reflagging. The host rocks consist of metasediments and basalts, metamorphosed to amedium grade. There is strong folding and faulting in the area.We would like to receive proposals from you for mapping the anomaly with appropriate groundgeophysical methods. We are most interested in obtaining not only a detailed geophysical map of theanomaly, but also a geological understanding of the relationship of the anomaly with the local geology.We believe there is some ground evidence of faulting; we would like the results of the field work to clearlyidentify any faults and to allow some interpretation to made of the sub-surface structure of the anomaly,especially the dip and strike. Due to the small size of the survey team, we are willing to provide someaccess to prior survey information to enable you to optimize your surveys.5

How to get high marks in Geology 409In the past students marks for the course tend to be in the low eighty percent range. High eighties are notuncommon. Marks over 90 percent are certainly not unheard of. To get these marks your written workneeds to be of a high standard. Your first reports may be disappointing, but I will always give you plentyof feedback. Pay attention to everything I write on your reports and the feedback I give in class. Avoid thepet peeves below like the plague – it will pay dividends on your final mark.The most critical thing for you to get across in your reports is that you understand the methods you areusing. If you don’t understand while you are doing the survey this is a sure recipe for poor reporting. Askfor help in the field – there are three people who are there to help; on the field trip there will be four.Pet PeevesThere are a number of common mistakes made by students when writing reports that simply should notoccur. If you avoid these errors you will put yourself in a good position for high marks in Geol 409.1. Incorrect usage of “data”:Data is a plural noun (plural of datum). Write “the data were processed”, not “the data wasprocessed”.2. Inconsistent use of tense:When describing your work, do not mix past, past perfect, present and future tense. Decide whichtense is appropriate and use it. As an example of this mistake: “This is done by changing theparameters until the model data corresponded to the field data”. Instead, write: “This is done bychanging the parameters until the model data correspond to the field data”.3. Use of slangDo not use slang in written reports. Examples that should be avoided are “typo”, “tweak” ,“stuff”,“a couple more readings ...”, etc.4. Overly long sentences or paragraphsA paragraph of text should contain only one, central idea. Break up paragraphs if they become tolong, and re-arrange text accordingly. Overly long sentences are usually the result of poor writingstyle. A little editing of long sentences can make your written work much more readable. Usuallythe word “however” should be used at the beginning of a new sentence, instead of in the middle ofa long sentence.5. Poor proofreadingSpell checking, while important is not enough. Read your reports back to yourself (aloud ifnecessary). Spell checkers will not catch these mistakes: “The angel of dip was quiet gentle”, or“the subsurface pie was found ...” (these are from real G409 reports!).6

6. Incorrect usage of geophysical termsThere are a number of words often used in describing geophysical work: “modeling” (noteCanadian spelling), “processing”, “plotting”, “interpreting”, “data fitting”, “inverting” all havespecific meanings, and may not be interchanged.7. Incorrect past participlesIncorrect: “the data were inputted”. Correct: “the data were input”.8. Overstating conclusionsThis is very specific to geophysics: your conclusions will hardly ever be definite. Unless you havevery good reason, do not state your conclusions without expressing this uncertainty. Do not write“the anomaly corresponds to a pyrrhotite zone” unless you are 100% sure that the mineral ispyrrhotite. Instead, write “the anomaly is consistent with the presence of pyrrhotite”. If you haveother information that supports your view, state this. In the example, you could then write “Thepresence of pyrrohotite is also strongly suggested by the style of mineralization in the area”.Remember: even if you have a model that explains all of the data, this is not a proof that yourmodel is a unique and true interpretation. There are almost always alternative models that explainthe data.9. Figures and tables are not to be relegated to appendices unless appropriateIn spite of what you may have been taught in other courses, figures and tables are an integral partof the text of a geophysical report and should appear within the body of the text at appropriatelocations. Forcing a reader to flip back and forth from text to appendices is unhelpful (would youlike to read a textbook like this?). All figures and tables must be numbered and captioned, andreferences to these figures must appear within the text in numerical order. Include a smalldescriptive sentence or two in the captions to help the reader.10. Appendices are useful in certain casesAppendices are indeed useful and should be used for lengthy mathematical discussions, largeamounts of detailed data or discussions that are not central to the main argument. Appendices maycontain figures, but the same rules apply - the figures must appear within the text of the appendix.All appendices must contain at least an introductory paragraph of text.11. Maps are important and must meet minimal standardsMaps are a crucial element of geophysics. We must know exactly where the surveys took place,and we must be able to produce maps of our geophysical anomalies. There are well knownstandards for map drawing in Geoscience, taught in field methods courses and field school. Forexample, all maps must be legible and have a title, scale, North arrow, legend etc. Many mapsavailable on the internet and those produced by certain software packages do not meet thesestandards - this is not a valid excuse and it is your responsibility to ensure standards are met, ifnecessary by redrawing by hand.7

Week 8 (Oct 30 th – Nov 3 rd ):Mon: Open for field trip modelling/processing/writing up etc.Tues: Open for field trip modelling/processing/writing up etc.Thurs: Open for field trip modelling/processing/writing up etc.Fri: Major field trip written reports due 4:30 pmWeek 9 (Nov 6 th -Nov 10 th ):Mon: Lecture on 3D Seismic interpretationTues: Lecture on 3D Seismic interpretationThurs: Lab on 3D Seismic interpretationWeek 10 (Nov 13 th -Nov 16 th ):Mon: Open for 3D Seismic interpretationTues: Open for 3D Seismic interpretationThurs: Open for 3D Seismic interpretationWeek 11 (Nov 20 th – Nov 24 th ):Mon: Open for 3D Seismic interpretationTues: Open for 3D Seismic interpretationThurs: Open for 3D Seismic interpretationWeek 12 (Nov 27 th – Dec 1 st ):Mon: Open for 3D Seismic interpretationTues: Open for 3D Seismic interpretationThurs: Open for 3D Seismic interpretationFri: 3D Seismic interpretation reports due. Course ends.9