WRITING A GEOLOGICAL REPORT

WRITING A GEOLOGICAL REPORT   Geological reports are concise, informative and well documented reports used to present, analyse and summarize field data for both industry and research purposes. They should be accompanied by geological maps, figures, stratigraphic columns, tables, graphs, etc. The following notes are some basic instructions on how to prepare the geological report for Rouchel and Bermagui field trips. Follow the instructions provided by your lecturer but use these as a guide on how to structure your report. Format Keep in mind the word or page limit set by the lecturer  Follow specified font size, line spacing and page Start with the title page (including your name) or student number Number all pages  Include your own field sketches or photo (if you are using someone else’s photos remember to give them credit. Place figures within the text rather than at the end of the report.  Figures and Tables Graphs, photos and diagrams/sketches are all considered figures. Add a brief, informative caption to the figures.   Each figure and table should be sequentially ordered (Figure 1, Figure 2, Figure 3, etc.).  For any photos or diagrams ensure there is a scale and the direction of view (North, South, South-West etc.) in the figures or figure caption.  Always quote the figures in the text when appropriate (place the figure number in brackets after you have discussed what the figure is showing). Plates Plates are the larger documents (usually shared as a group) and include Geological Maps, Stratigraphic Column and Cross Sections  Plates are handed in separately to the report as they are larger documents but place an A4 copy of the plates at the back of your report (makes it easier for the marker to access the plates) Always quote the plates in the text when appropriate (e.g. Plate 2). Appendix Appendix is the place to put the data table with the list of outcrops and their grid references (as well as the observations and any data obtained at each outcrop) References Remember to always quote the original source of the text and place in the reference section.  Never use other people’s observations without quoting them because doing so is plagiarism. This includes using data from neighboring field areas. Sections of the Report  The Report should contain the following headings, numbering the sections is optional as long as they are clearly identified and  placed in the table of contents. It is also acceptable to break each section down with subheadings (ensure they are clearly labeled), for example having a different subheading for each lithology (under Stratigraphy). 1. Abstract 2. Introduction 3. Stratigraphy and Lithology  4. Structures 5. Geological History 6. Conclusions 7. References. 1. Abstract  The abstract should be a stand- alone, informative summary of observations and interpretations. The abstract must be brief but must include: where is the investigated area  which type of work has been carried out (e.g. field mapping, sampling, geophysical survey, drilling etc.),  what is the goal of the work (e.g. establishing the stratigraphic sequence, dating formations, recognizing structures, finding ore minerals etc.),  what are the results obtained (e.g. completion of a geological map and stratigraphic columns). 2. Introduction The Introduction gives the extended information on why ?, where ?, how ? and what ? Write this section for an experienced geologist who does not know the region. why is the work done? where exactly is the area located? (both the geological and geographic location e.g. Rouchel is in the north-west region of the Hunter Valley, NSW but geological sits within the Rouchel Block of the Tamworth Belt in the south-easterly end of the New England Orogen) how has the work been done? (field mapping, what measurements were taken) what has been achieved? (creation of a geological map, mention the number of plates accompanying the report) explain the general plan of the report? (contains the description of the stratigraphy, structures and they are both used to reconstruct the geological evolution of the area during a certain time interval) 3. Stratigraphy and Lithology  This is where you demonstrate the quality and accuracy of your field work and observations. The stratigraphy and lithology section combines all your field observations and interpretations. Remember this section is not a diary of visited outcrops, a list of what you have done, or a written description of the map. The description of lithology must proceed from the oldest to the youngest. It should be accompanied by a stratigraphic column and appropriate field sketches and photos of specimens and outcrops. Refer to your map whenever possible to locate outcrops and samples. When describing rock units, always state where they located in outcrops and the best locality for exposure and sampling (include relevant figures). You may refer to your geological map and a table (appendix) with the list of visited outcrops. As a general rule remember to give the following information: Basement terranes Type of terrane (metamorphic / sedimentary / igneous)  Lithology (rock type) and name of rock unit (for metamorphic rocks also mention the parent rock (sedimentary or igneous) and the metamorphic grade) Rock petrography (coarse/fine grained, mineralogy etc.) Thickness of the unit (if known) Age of the parent rock and age of the metamorphic imprint Sedimentary units Basal boundary of the unit (is it visible, is it an unconformity, is it a fault).  Lithology (including grain size, type of clasts, mineralogy of grains etc).  Classify the rock (claystone, mudstone, limestone, sandstone etc.) and give the name of the rock unit.  Type of bedding (massive, well bedded, alternating beds etc) and thickness of individual beds  Facies and depositional environment - terrestrial (fluvial, lacustrine) or marine (shallow, deep) Fossil content and age of unit Thickness of entire unit (you may also calculate this from your cross sections)  Igneous units Lithology, mineral content, texture, rock type  Igneous facies (flow, dyke, sill) and contact with the surrounding rock units Thickness  Age 4. Structures First define if the area is strongly or mildly deformed (is the bedding horizontal, dipping or vertical?) and if the structures have been formed in a compressional or extensional regime, or if there is a transition from one to the other through time. Clearly separate ductile structures (foliation, schistosity and folds in the metamorphic units) from brittle structures in the sedimentary and volcanic units (joints, faults and folds). Start with the oldest structures and work through to the youngest structures. Always include relevant sketches, stereonets and photos as well as referring to maps and cross sections. Description of folds must include:  Geometry of the folded layer and fold morphology (syncline, anticline)  Fold dimensions (wavelength, amplitude)  Orientation and dip of axial plane and trend and plunge of the fold hinge line  Evidence for superposed folding (typically in metamorphic rocks)  Age Description of faults must include:  Fault dimensions (at least length as mapped at the surface)  Strike, dip direction and angle of dip of fault surface  Rake of striations (if present)  Sense of movement (normal, reverse, dextral, sinistral or oblique)  Are there systems of faults? (parallel sets, conjugate sets)  Displacement of geological markers and amount of offset  Age (define crosscutting relationships between structures of different age) 5. Geological History The geological history is a brief history of the evolution of your investigated area through time, as inferred from your field evidence. Always describe the evolution from the oldest event to the youngest event. Start with the basement rocks, defining the time of deposition, metamorphic conditions and time of metamorphism. Use presence, age and duration of unconformities to separate distinct cycles within the main stratigraphy sequence. Is the sequence terrestrial or marine? Is there a transition from terrestrial to marine conditions? Is the marine sequence shallowing or deepening upwards?  Are there unconformities within the sequence?  Are there igneous events that interrupt the sedimentary sequence? What is their age?  What is the age of the youngest sediments preserved in outcrop?  When was the area uplifted?  When were the units deformed? 6. Conclusions  A brief summary of everything that the work has achieved (production of a geological map, cross sections and stratigraphic columns, discovery of new outcrops or fossil localities, construction of the geological history) 7. References All publications used in the text should be noted in a list of references at the end of the report. Modified from Department of Geology, University of Otago (link)