[
    {
        "id": "thesis:7295",
        "collection": "thesis",
        "collection_id": "7295",
        "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:11292012-100814038",
        "primary_object_url": {
            "basename": "Burt_ea_1993.pdf",
            "content": "final",
            "filesize": 56216940,
            "license": "other",
            "mime_type": "application/pdf",
            "url": "/7295/1/Burt_ea_1993.pdf",
            "version": "v5.0.0"
        },
        "type": "thesis",
        "title": "Oxygen isotope studies of some sedimentary and metasedimentary rocks of the central and northern Appalachian Mountains, the Colorado Plateau, and the Ouachita Mountains",
        "author": [
            {
                "family_name": "Burt",
                "given_name": "Emelia Anna",
                "clpid": "Burt-E-A"
            }
        ],
        "thesis_advisor": [
            {
                "family_name": "Taylor",
                "given_name": "Hugh P.",
                "clpid": "Taylor-H-P"
            },
            {
                "family_name": "Rossman",
                "given_name": "George Robert",
                "clpid": "Rossman-G-R"
            }
        ],
        "thesis_committee": [
            {
                "family_name": "Rossman",
                "given_name": "George Robert",
                "clpid": "Rossman-G-R"
            },
            {
                "family_name": "Epstein",
                "given_name": "Samuel",
                "clpid": "Epstein-S"
            },
            {
                "family_name": "Wyllie",
                "given_name": "Peter J.",
                "clpid": "Wyllie-P-J"
            },
            {
                "family_name": "Burnett",
                "given_name": "Donald S.",
                "clpid": "Burnett-D-S"
            }
        ],
        "local_group": [
            {
                "literal": "div_gps"
            }
        ],
        "abstract": "<p>Terrigenous sedimentary rocks from the Colorado Plateau show a relatively\r\nuniform bulk silicate \u03b4^(18)O of +14.8 with an SEM of 0.32. Shales and calcilutites in this\r\nregion have a mean bulk silicate \u03b4^(18)O of +17.7 which is significantly heavier than the\r\nmean for interbedded sandstones and siltstones. Bulk silicate \u03b4^(18)O is decoupled from\r\ncarbonate \u03b4^(18)O due to differences in mode of deposition and diagenetic behavior.</p>\r\n\r\n<p>Central Appalachian terrigenous sedimentary rocks show a surprisingly uniform\r\nbulk silicate \u03b4^(18)O of +14.8 with an SEM of 0.1. The mean bulk silicate \u03b4^(18)O for all\r\nshales (+15.2) is only 0.3 per mil heavier than the mean for all sandstones and siltstones\r\n(+14.9). The oxygen isotope uniformity of Central Appalachian sedimentary rocks is\r\nmainly a primary depositional feature that is the result of thorough, grand-scale mixing of\r\nterrigenous sediment in the Appalachian geosyncline, probably involving several cycles of\r\nsedimentation, uplift, erosion, and reworking extending over hundreds of millions of years\r\nduring the Paleozoic era. The bulk silicate \u03b4^(18)O of siltstones and shales shows a\r\nsignificant (P \u02c2 0.05)  correlation with conodont color alteration index, which is a measure of\r\ndiagenetic temperature. As a result of isotopic exchange with porewater during diagenesis,\r\nthe bulk silicate \u03b4^(18)O of shales and siltstones can apparently be lowered by as much as 2.5\r\nto 4.0 per mil. These diagenetic effects contributed to the overall homogeneity of these\r\nsedimentary rocks because the shales started out at higher \u03b4^(18)O.</p>\r\n\r\n<p>A reconnaissance ^(18)O/^(16)O study of 14 samples of terrigenous sedimentary rocks\r\nfrom the Ouachita Mountains suggests more inherent isotopic variation in these samples,\r\nperhaps in part as a result of greater heterogeneity of source regions. Some of the isotopic\r\nvariation also seems clearly attributable to diagenetic effects. A significant (P \u02c2 0.05)\r\ncorrelation was found between mean vitrinite reflectance, also a measure of diagenetic\r\ntemperature, and the bulk silicate \u03b4^(18)O difference between shale-sandstone pairs in three\r\ndifferent sedimentary formations.</p>\r\n\r\n<p>Northern Appalachian metasedimentary rocks show a decrease in bulk\r\nsilicate \u03b4^(18)O at garnet grade and higher. The terrigenous facies metamorphic rocks have\r\nbeen depleted in ^(18)O by about two per mil relative to their unmetamorphosed counterparts\r\nin the Central Appalachians, except where they are adjacent to carbonate-rich sections.\r\nCarbonate facies metasedimentary rocks are 5 to 6 per mil higher than interbedded\r\nterrrigenous facies rocks, but at the margins of that formation there is a distinct lowering of\r\nbulk silicate \u03b4^(18)O and carbonate \u03b4^(18)O due to influx of metamorphic hydrothermal fluids\r\nfrom the adjacent terrrigenous rocks. This is attributed to the involvement of isotopically\r\nlight fluids during metamorphism. Further work is need to elucidate the differences\r\nbetween metamorphic processes in pelitic and calcareous sediments.</p>\r\n\r\n\r\n",
        "doi": "10.7907/qgxa-rq43",
        "publication_date": "1993",
        "thesis_type": "phd",
        "thesis_year": "1993"
    }
]