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The AAPG/Datapages Combined Publications Database

AAPG Bulletin

Abstract


Volume: 64 (1980)

Issue: 5. (May)

First Page: 708

Last Page: 709

Title: Controls of Zeolite Cementation in Upper Jurassic Sandstones, Lower Cook Inlet, Alaska: ABSTRACT

Author(s): Stephen G. Franks, David M. Hite

Article Type: Meeting abstract

Abstract:

Field and petrographic studies indicate that the major factors controlling zeolite cementation in Upper Jurassic sandstones of Lower Cook Inlet were provenance, depositional environment, and igneous activity. The Jurassic strata record the unroofing of a Mesozoic volcanic-plutonic arc complex related to subduction and plate accretion beginning at least by Triassic time. Petrologic-stratigraphic trends show a striking increase in the ratio of quartz to volcanic rock fragments from Lower Jurassic to Upper Jurassic sedimentary rocks, reflecting

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increasing depth of erosion of the arc complex. Superimposed on these trends are local variations in mineralogy related to differences in depositional environment. For example, shallow-marine, tidal sandstones of the Upper Jurassic Staniukovich Formation contain an average of Q48F42L10 whereas the underlying Upper Jurassic Naknek, a deep marine deposit, averages Q4F58L38. The Naknek was tightly cemented with heulandite during shallow burial as unstable volcanic material altered. Only minor heulandite is found in the Staniukovich which was mineralogically much more stable. Subsequently, however, laumontite cement destroyed much porosity in the Staniukovich. Laumontite clearly postdates heulandite cement and present evide ce suggests that laumontite cementation was a late event, perhaps related to Tertiary intrusion and volcanism. Depth of burial was not a major factor in zeolite cementation.

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