2006-PetRock-WritingGuidelines | Minerals | Granite

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   1 Guidelines for writing and scoring the Pet Rock Paper Fall 2006 – Darrell Henry Comments to the Igneous and Metamorphic Petrology Class:  In the past several common problems have cropped up in the preliminary written  presentation of the Pet Rock project. Rather than make the same types of comments on many of the papers, I put together the following guideline that should help you decide where certain information should go and what should be addressed. There are also sources of images and data that you may have forgotten about and could possibly use for the paper or PowerPoint  presentation. It is important that you make the appropriate citations of ideas in the paper and images/figures in the paper and PowerPoint presentation. The rubric that will be used for scoring different aspects of the Pet Rock Paper is italicized and underlined . General comments on constructing paragraphs in a scientific paper . General writing style of paper: (30/30)  When you write a paragraph the lead sentence in the paragraph should basically answer the question “What is the news? Or what is the important idea?”, and the rest of the paragraph should explain it. When you are finished with your paper you should be able just read the first sentence of each paragraph and get the essence of the paper. Below is an example from one of my papers (Henry, D. J. and Dutrow, B. (2001) Compositional zoning and element partitioning of nickeloan tourmaline in a metamorphosed karstbauxite from Samos, Greece. American Mineralogist, 86, 1130-1142).    Natural tourmalines contain a wide range of elements, but those with substantial amounts of Ni and Co are relatively unusual. In most cases, tourmaline with high Ni contents also has high Cr levels because the tourmaline-bearing rocks are associated with meta-ultramafic rocks (e.g., Challis et al. 1995; Michailidis et al. 1995). For instance, a chromian dravite (8.5 wt% Cr  2 O 3  ), from a calcareous rock in contact with serpentinite, has the highest  Ni level previously recorded in tourmaline, 0.75 wt% NiO [0.1 atoms per formula unit (apfu)] (Jan et al. 1972; Henry and Dutrow 1996). The recorded concentration levels of Co in tourmaline are even lower, with the maximal reported Co being 45 ppm in a tourmaline  from an aplite (Power 1968; Henry and Dutrow 1996). Use of images in the paper (30/30) Sections that should be included in Pet Rock Paper (bold) Title:   (10/10)  Come up with a title that expresses what you did and the importance of the study. A title such as: “Amphibolite xenolith in Late Archean Granitoids of the Beartooth Mountains, Montana-Wyoming: Evidence for interaction with granitoids”  would be an appropriate type of title.  Abstract (30/30) You need an abstract that tells the reader what you found. This does not have to be long – generally 200-400 words. However, it is commonly the only thing that a reader might see. So it has to express the important points that you want to convey in a relatively few words.   2  Introduction   (30/30) This section is very important because it will draw the reader in. You want to express to the reader why your project is significant (in other words “Why should I care?”). For example, if you are working on a mafic xenolith in the Long Lake granite you might want to start your introduction with a sentence something like:  Mafic xenoliths in granitic rocks commonly  preserve the only information about the earlier crustal constituents and the nature of the thermal conditions prior to the intrusion of the granitic melts.  After you have explained why your study is significant you need to state your hypothesis or “purpose of study” and explain how you are going to test the hypothesis. It might be something like “The purpose of the study is to investigate textural and chemical evidence for an earlier metamorphism and to determine the PT conditions that were preserved in the amphibolite. This will be accomplished through detailed petrographic and mineral chemical investigations of the amphibolite” Geologic Setting (20/20)  I would suggest starting with a discussion of the general history of the Beartooth Mountains  beginning with information on the Archean and emphasizing that this is part of the Beartooth-Bighorn Magmatic Terrain (BBMT). You may want to include a figure with these different terranes (A good source is the Geologic background powerpoint that I gave – link: http://www.geol.lsu.edu/henry/Geology3041/labs/PetRockProject/PetRockProject-GeologicBackground.ppt ).  Next discuss later events including the Laramide uplift that produce the current Beartooth Mountains. Note that Sevier Orogeny probably is not a significant player in this area. Use the “Selected Features of the Beartooth Mountains…” paper that I gave to you for the  parts of the geologic history that you may want to emphasize. A link to the pdf of this is http://www.geol.lsu.edu/henry/Research/Beartooths/EasternBeartoothHistory.pdf . The reference is “Henry, D. and Mogk, D. (2003) Selected Features of the Precambrian Rocks of the eastern  Beartooth Mountains, Montana and Wyoming. Teaching Petrology in the 21st Century Workbook, section 3, 18 pp.” . The last part of the section should be about the geographic location of the sample any field information you might have. A good location map for the BTR, HR and QC samples is on the information webpage: http://www.geol.lsu.edu/henry/Geology3041/labs/BeartoothBackground/BeartoothMtns.htm Sample preparation and analytical procedures (30/30)   This section should contain information on several topics: ã   rock preparation o   hand sample acquisition and description [not the actual description, but the fact that you did one as part of a systematic process] o   rock cutting procedures o   thin section procedures ã    petrographic descriptions [not the actual description, but the fact that you did one] ã   analytical procedures   3 o    backscattered image acquisition and its usage for mineral identification and electron microprobe analytical point locations, and o   electron microprobe analytical conditions o   normalization procedures for the minerals that you used for the minerals that you analyzed  Below is an example of the type of electron microprobe analytical procedure that I have used in one of my papers (Henry, D. J. and Dutrow, B. (2001) Compositional zoning and element  partitioning of nickeloan tourmaline in a metamorphosed karstbauxite from Samos, Greece. American  Mineralogist, 86, 1130-1142).    Electron-microprobe analysis Tourmaline, staurolite, gahnite, muscovite and paragonite were quantitatively analyzed by wavelength-dispersive spectrometry (WDS) using the automated JEOL 733 electron microprobe at LSU. WDS analyses were done at an accelerating potential of 15 kV and 5-20 nA using a 1-5 µ  m electron-beam diameter, depending on the mineral.  Lower sample current and wider beam diameters were used for mica analyses. Standards were well-characterized synthetic and natural minerals, including andalusite (Al), diopside (Ca, Mg, Si), fayalite (Fe), chromite (Cr), synthetic glasses (V, Ni, Co), kaersutite (Ti), rhodonite (Mn), willemite (Zn), albite (Na), sanidine (K) and apatite (F). Several well-characterized tourmalines and staurolites served as secondary standards to ensure good-quality analyses (Dutrow et al. 1986, 1999; Holdaway et al. 1986; Henry and Dutrow 1990). Micas and gahnite were normalized on the basis of 11 and 4 oxygens, respectively. Results (50/50)  This section should contain information on several topics: ã   hand sample description o   general appearance and observed mineralogy o   any textures (e.g. foliation, lineation, crenulation cleavage, etc. ã    petrographic description o   mineralogy, mineral dimensions and mineral modes (and variations if it is a heterogeneous sample) o   maybe add the thin section scan that is on http://www.geol.lsu.edu/henry/Geology3041/labs/BeartoothBackground/2005-PetRockImages.htm and any digital photomicrographs that you took o   optical heterogeneity (color or optical zoning) o   textures of minerals (e.g. lineation, foliation of specific minerals) or replacement o   alteration of minerals (e.g. sericitization of plagioclase, chloritization of biotite, etc.) o    proper petrologic rock name based on the major minerals and textures ã    backscattered image o   Description of the image and any additional noteworthy features o   Analytical points on image ã   Electron microprobe analyses o   Tables of mineral analyses including the weight % oxide data and normalized atoms  per formula unit (from STOICH program). I will be sending some Excel files that should help you out here.   4 o   Discussion of what kind of minerals you are dealing with (e.g. plagioclase An 25-28 ; edenitic hornblende). (This is part of the STOICH program. If you don’t have the information, see me.) o   Comparison of biotite and amphibole data with other rocks from class (comparison  plots: http://www.geol.lsu.edu/henry/Geology3041/labs/BeartoothBackground/BeartoothMtns.htm ). Discussion/conclusions (30/30)    – This section should contain information on several topics: ã   Information on PT conditions o   Hornblende-plagioclase bearing rocks should include the following:    Holland and Blundy, 1994 geothermometer assuming the best estimate of P    discussion of whether this rock has the appropriate mineral assemblage    note the estimated uncertainties o   Hornblende-bearing rocks should include:    Ernst and Liu, 1998 geothermobarometer for both P and T     Note the uncertainties o   Biotite-bearing rocks    Henry et al., 2005 Ti-in-biotite geothermometer    Suitability of rock for application of this thermometer    Uncertainties o   Garnet-biotite rocks    Berman TWQ geothermometer o   Plagioclase-feldspar rocks    2 feldspar thermometer for igneous rocks o   General assemblage information relative to a petrogenetic grid (e.g. sillimanite-cordierite-biotite or garnet-cordierite-biotite assemblages). ã   Discussion of where this rock fits into the history of the area and any discussion as to where is might have come from (e.g. basalt, granite, mantle…) o   If there is whole rock data, this is a good place to discuss the potential srcinal extrusive rock type using the TAS diagram, and discuss possible igneous mineralogy using a CIPW calculation (although you should remember the limitations of the CIPW norm, esp. they do not include hydrous minerals like biotite or amphibole in the calculations.) ã   Anything else that you think might be important. Acknowledgements   (10/10)    – Thank all those that assisted you in completing this task. References cited   (10/10)    – Include all of the references that you cited in your paper in the format used by American Mineralogist. Appendices  – These are optional, but could include things like your petrographic reports, tables from the probe, or anything else you may not want to put in the main text.
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