Figure F5. Pictured on the left are core photographs with sample intervals and scales as in Figure F3, . Stars highlight intervals corresponding to photomicrographs on the right (all in plane-polarized light). A. Darker rounded grains are microporous microlitic fragments, whereas light blue grains represent dissolved glassy (?) debris. Rounded green glauconite is present in upper left. B. Black glassy (tachylite) fragment in center contains partly dissolved plagioclase laths. C. Grains consist of a mixture of secondary pores after blocky to vesicular glass (blue), tachylitic glass (black), and glass altered to clay minerals (brown). White crystals are secondary zeolites. Grains are outlined by authigenic clay mineral cements. D. Lower magnification view showing grain-supported nature of this very fine grained volcaniclastic sandstone. Note white rectangular plagioclase crystals and sparse green glauconite grains. Blue porosity is dominantly secondary in origin.

Figure F5. Pictured on the left are core photographs with sample intervals and scales as in Figure F3. Stars highlight intervals corresponding to photomicrographs on the right (all in plane-polarized light). A. Darker rounded grains are microporous microlitic fragments, whereas light blue grains represent dissolved glassy (?) debris. Rounded green glauconite is present in upper left. B. Black glassy (tachylite) fragment in center contains partly dissolved plagioclase laths. C. Grains consist of a mixture of secondary pores after blocky to vesicular glass (blue), tachylitic glass (black), and glass altered to clay minerals (brown). White crystals are secondary zeolites. Grains are outlined by authigenic clay mineral cements. D. Lower magnification view showing grain-supported nature of this very fine grained volcaniclastic sandstone. Note white rectangular plagioclase crystals and sparse green glauconite grains. Blue porosity is dominantly secondary in origin.