SEDIMENTARY Ge192 GEOCHEMISTRY ON EARTH AND MARS
Topic 6. Provenance and Component Analysis
Because of the development of rapid, in situ analytical methods (both chemical and isotopic), there has been an increasing tendency to evaluate sediment provenance on a "grain by grain" basis in order to establish the distribution and relative importance of the various provenance components. However, in doing so one must face a series of geological and statistical issues bias and representativeness in the minerals chosen for analysis (e.g., Do feldspar and zircon provide the same information? Is the sampling random?), nature of age distributions (normal vs. non-normal), detection limits, uncertainties, and so forth. In this section, we will briefly review some of the chemical and isotopic approaches to "component analysis". An important point that will be emphasized is the possible difference in provenance information that comes from the study of major framework components (quartz and feldspar) and minor components (notably zircon). We will then briefly review some of the statistical considerations in interpreting detrital mineral age distributions. We will end with comments on using geochemistry to quantitatively identify tectonically or otherwise important "exotic" (unusual, low abundance) components with examples from both Earth and Mars. Geochemical approaches using detrital components 1. Trevena, A. S. and Nash, W. P. (1981) An electron microprobe study of detrital feldspar. J. Sed. Petrol., 51, 137-150. 2. Maynard, J. B. (1984) Composition of plagioclase feldspar in modern deep-sea sands: relationship to tectonic setting. Sedimentology, 31, 4923-501. 3. Power, M. R., Pirrie, D., Anderson, J. C. O. and Wheeler, P. D. (2000) Testing the validity of chrome spinel chemistry as a provenance and petrogenetic indicator. Geology, 28, 1027-1030. This paper presents a skeptical view of relating detrital mineral compositions (in this case Cr-spinel) to provenance (and petrogenesis of the provenance rocks) in any simple way. Isotope tracers and geochronology using major components 4. Tyrrell, S., Haughton, P.D.W. and Daly, J. S. (2007) Drainage reorganization during breakup of Pangea revealed by in-situ Pb isotopic analysis of detrital K-feldspar. Geology, 37, 971-974. 5. Clift, P. D., Shimizu, N., Layne, G. D. and Blusztajn, J. (2001) Tracing patterns of erosion and drainage in the Paleogene Himalaya through ion probe Pb isotope analysis of detrital K-feldspars in the Indus molasses, India. Earth Planet. Sci. Lett., 188, 475-491. 6. Hemming, S. R., McLennan, S. M. and Hanson, G. N. (1994) Lead isotopes as a provenance tool for quartz: Examples from plutons and quartzite, northeastern Minnesota. Geochim. Cosmochim. Acta, 58,4455-4464. Isotope tracers and geochronology using minor components 7. Gehrels, G. E., W. Dickinson, R., Ross, G. M., Stewert, J. H. and Howell, D. G. (1995) detrital zircon reference for Cambrian to Triassic miogeoclinal strata of western North America. Geology, 23, 831-834. An early classic paper in the field note that they use convention mass spectrometry techniques but still a lot of data (>600 zircons!).
8. Cawood, P. A., Nemchin, A. A., Freeman, M. and Sircombe, K. (2003) Linking source ans sedimentary basin: Detrital zircon record of sediment flux along a modern river system and implications for provenance studies. Earth Planet. Sci. Lett., 210, 259-268. 9. Fedo, C. M., Sircombe, K. N. and Rainbird, R. H. (2003) Detrital zircon analysis of the sedimentary record. Rev. Mineral. Geochem., 53, 277-303. 10. Bodet, F. and Schrer, U. (2000) Evolution of the SE-Asian continent from U-Pb and Hf isotopes in single grains of zircon and baddeleyite from large rivers. Geochim. Cosmochim. Acta, 64, 2067-2091. A nice example of using multiple isotopes on single grains. 11. Hemming, S. R., Broecker, W. S., Sharp, W. D., Bond, G. C., Gwiazda, R. H., McManus, J. F., Klas, M. and Hajdas, I. (1998) Provenance of Heinrich layers in core V28-82, northeastern Atlantic: 40 Ar/39Ar ages of ice-rafted hornblende, Pb isotopes in feldspar grains, and Nd-Sr-Pb isotopes in the fine sediment fraction. Earth Planet. Sci. Lett., 164, 317-333. Statistical Approaches Set of papers published over ~20 years illustrating the development in thinking behind the statistics of detrital grain age populations. 12. Dodson, M. H., Compston, W., Williams, I. S. and Wilson, J. F. (1988) A search for ancient detrital zircons in Zimbabwean sediment. J. Geol. Soc. London, 145, 977-983. 13. Sambridge, M. S. and Compston, ...