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SENT BY~FS &T, L C, U ~ - - 9 CARBON GEOCE•{EMISTRY • In order to properly evaluate the relative significance of whole-rock geochemical analyses obtained from the RGPCC site (Tract "B"), it is desirable to compare these data to bath nearby and distant exposures of the Fort Hays Member. Therefore, geochemical data for three sections of the Fort Hays are used in this section for comparative purposes: 1. Wolcott, Colorado (Eagle County) 2. Badito, Colorado (Huerfano County) 3. Wagon Mound, New Mexico (Mora County) A comprehensive List of all values from these sections ate provided in the Appendix. Studies of the light stable isotopic and geochemical signatures of Middle Cretaceous organic-rich sediments of the Western Interior have recently provided the geological and paleontological community with important data on the paleoenviron- ments of epicontinental seas and their dynamics through time (Pratt, 1984; Barlow, 1986; Arthur er al_, 1988; Hayes er aL, 1989, among others). These studies have fortunately preceded in close allegiance with High Resolution Event Stratigraphic techniques (Herrin, 1964; Kauffman, 1988), allowing far centimetre-scale documentation of short-term physical and chemical events_ Inasmuch as these events probably do not represent more than a few tens to thousands of years each in duration (which may appear as -cm thick latttina in fresh exposures), sampling intervals must be on the order of every 5 to 20 cm to • insure sufftciently detailed, high confidence level results. Portions of the data presented in this study, in regards to overall sampling resolution, varies somewhat between 10 and 2tl cm (sec Appendix). ?his material is included herein to provide some evidence for the relatively trnalrered state of the Fan Hays Member on the RGPCC property and proposed quarry site, particulat'ly in reference to post-burial diagenesis (physio-chemical alteration of rock by penetrating groundwater). The interpretation of carbon, oxygen, and sulfuY stable isotope data from Cretaceous marine strata has proven difficult (Didyk er aL, 1978), due in large part to the lack of inodern analogs for envirotunental comparison (Kauffman, 1987). For instance, oxygen isotope studies have shown a close correspondence to the glacial-interglacial cecord of the past 800 Kyrs (bmiliani and Schaekleton, 1974; Hays er al., 1476), but the cyclic fluctuations of isotopic oxygen in pelagic-hemipelagic sediments has required much additional inference. It is now widely recognized that global latitudinal climatic conditions during the Upper Cretaceous were likely much more ameliorated than those characteristic of the Quaternary. What effects this very different Mesozoic world may have had on oceanic carbon, sulfur, phosphorous, and oxygen cycles aze only beginning • 1499