Notes for Reading Geochemical Fingerprints Notes for Reading Geochemical Fingerprints Go over syllabus structure of class introduction of some applications so have road map of how geochemistry used, P[.]
Notes for Reading Geochemical Fingerprints Go over syllabus structure of class: introduction of some applications so have road-map of how geochemistry used, Processes of differentiation, Statistical methods Analytical methods Applications 2-times through approach: go through processes and analytical methods, then see them again as we go through applications Text book picks up mainly in the applications puzzle solving homework assignments and some labs These to be done mostly outside of class Will set up times for lab to be open in evening exams, First will cover processes and analytical techniques, 2nd will cover applications Report to class on a published paper using geochemistry to address some problem about 20 minutes each (for 10 students) Mostly Archaeological examples….some environmental or geological feel free to correct my pronunciation! Deemphasize details of chemical processes, chemical equilibrium But cover it some There is not single or simple procedure for applying geochemical methods to archaeological finds Have to be creative and innovative If you don’t understand how geochemical differentiation works, then can’t be creative or innovative in applying it Colossi of Memnon: (use computer graphic or overhead, showing N and S Colossi) (goal: start thinking about uncertainty in data and what it means, how a graph helps understand that uncertainty and whether data distinguish two materials as being different or the same) built 3200 years ago, 18th Egyptian dynast, memorial for Amenhotep III, set up on West bank of Nile Invading Assyrians in the 7th century BC, and Persian in 6th and 5th centuries, tried to destroy (Assyrians in particular liked to obliterate people and culture to minimize future revolt) Built fires to try to crack stone But stone made of Quartzite…Monomineralic, and simple compositional structure (Quartz=SiO2) Also the structure of quartz is isometric, meaning its structure is the same in all directions It expands more evenly when gets hot Does not crack Also, coefficient of expansion not real high to begin with Efforts failed Earthquake succeeded in 27BC, Northern of the Colossi lost upper half of body Repaired by Roman emperor Septimius Severus about 200 years later (according to Greek Historian Strabo) Did repair use Quartzite from same area, or had area of active quarrying changed? Where was the quarry? Show computer graphic or overhead of map from Bowman et al 1984 Major quarries north and south of area of Colossi (Gebel el Ahmar, Silsila, Aswan) But quartzite made mainly of quartz Can’t always tell apart Sometimes trace constituents show up as color differences, or may be differences in minor minerals But Trace chemistry a good way to tell (explain trace chemistry) Data table (major elements) (hand out) Quarries at Silsila and Silwa strikingly different even in major element chemistry (show with CaCO3, and SiO2) Rear block looks like Aswan by SiO2 analysis But the problem is that SiO2 could not be measured by their analytical technique! It was calculated by subtracting everything else from 100% Not very credible Have them look at other elements and try to decide which quarry each came from (Rear block added by Romans, Main block part of original) explain “