35mm Optical Photomicrographs Descriptions - by depth

1186.5 ft. Negative 1. 40X Transmitted plane polarized light. Listed as high quality opal A, SO is 73%. This is from Note in particular: Center of photo has spherical silicious microfossils, calcareous tests, and pyritized (formerly calcareous test) microfossil at edge of photo. Hydrocarbon regions are dark and soft; alumina polishing compound is imbedded and can't be removed. Some replacement suggests reducing fluids (from presence of hydrocarbons (Slide 1 is the same section.)

1228.8 Negative 2. Plane polarized reflected light, 40X, 68.1% SO. Note that even at this level, hydrocarbons accumulate along fractures. There is also non-uniform distribution of hydrocarbon which is also apparent in hand specimen. Dark regions are hydrocarbon, brighter matrix. Bright grains are polishing compound, stuck in hydrocarbon rich regions. (SLIDES 2,3,4 are the same section.)

1230.4 Negative 3. 40x transmitted plane polarized light. This specimen from has So of 35.2, contrasting from 2 ft above which has 68.1%. This also shows hydrocarbon filled fractures although hydrocarbon content is much lower. This is Opal A. (SLIDES 5,6 are the same section.)

1399.SH Negative 4. 100x plane polarized transmitted light. This specimen has a permeability of 46 md. The section appears to be full of fractures but we often can't tell if fracture are preparation artifact. The vertical section also has fractures which parallel the bedding. There are small colorless crystal in some pores; they have parallel extinction. We may have secondary porosity developing at this depth. This is just 2 ft. above a "carbonate hard streak" bed. (SLIDE 7 is the same section.)

1424.5 Negative 21. 40x plane polarized light. Note fine grained, uniform hydrocarbon occurrence, transitional from Opal A to Opal CT. (no slides)

1522.6V Negative 20. No hydrocarbon segregation along fractures, although it is abundant. The microfossils are carbonate. SO is 35%. (No slides)

1526.7H Negative 8. 100x, plane polarized transmitted light. This one has abundant fossils and detrital grains; there is a lot of carbonate in this one (it is listed as carbonate hard streak). Spherical microfossils are filled with black hydrocarbon. It is not epoxy or it would be blue. (SLIDES 10,11,12 are the same section.)

1572.4V. Negative 22 40X Plane polarized transmitted light. This specimen has SO of 70.2, the next has 21.9 They do not look different! G.D. and K are identical. (Could they contain the same volume of hydrocarbon, just different saturations due to different porosities?). (SLIDES 13 to 20 are this section.)

1573.5 V Negative 23. (poor adhesion to slides). These two have very different hydrocarbon saturation. (SLIDES 21,22 are the same section.)

1631.SH Negative 7. This is a very interesting specimen- fractures and tests contain gypsum. They are also partially pyritized. Some of the pores are not hydrocarbon filled. The feldspars are also in a state of disequilibrium. Note accumulation of hydrocarbon along Fracture. 40x, plane polarized transmitted light. Also note structural difference from vertical cut (negative 6).

1631.5V Negative 6. 100x Plane polarized transmitted light: Carbonate test is partially replaced by pyrite. Blue epoxy penetrates open chambers; chambers also have some hydrocarbon. SEM Polariods 1636 to 1641 are from this specimen.

1723.7 Negative 9 and 10, different exposure times. 40X plane polarized transmitted light. Although the hydrocarbon has the undulating structure, the veins are also filled with hydrocarbon as well. Pods of hydrocarbon are offset by the fractures. (SLIDES 40 to 43 are the same section.)

1723.7 Negative 11. 100X plane polarized transmitted light. The vug with crystals inside, and hydrocarbon filled fracture suggest that hydrocarbon filling is not a preparation artifact.

1753.5V Negative 16. 40X plane polarized transmitted light. This vertical cut shows vertical variation in hydrocarbon which also segregate near the fracture. It is listed as cherty, and field is dark in crossed polars. The hydrocarbon acccumulates along the fractures in this one, and irregular shape looks like it might have moved along a water front. (SLIDE 44 is the same section.)

1753.SH Negative 17. 40X plane polarized transmitted light. This is listed as Cherty, and compared to 1753.5V. (the green edge along the fracture is a light reflection in the microscope). (SLIDE 45 is the same section.)

1754.5H Negative 18 100X plane polarized transmitted light. Note difference in hydrocarbon segregation in this silty specimen vs. cherty unit above, giving a "honeycomb" structure. (SLIDE 46 is the same section.)

1754.5V. Negative 19. 40x plane polarized transmitted light. Note that the fractures in this silty specimen do not have pronounced hydrocarbon accumulation, instead are segregated in bedding planes. Just above and just below are cherty specimens which have hydrocarbon-filled fractures. (SLIDES 47 and 48 are the same section.)

1757.5 H Negative 12. 40X plane polarized transmitted light. hydrocarbon segregates along the fracture in this "cherty" specimen. There does not seem to be a lot of hydrocarbon in this specimen. (SLIDES 50 and 51 are the same section.)

1757.5 Negative 13, 14. (30 sec and 15 sec). 100x, crossed polars. Very Cherty. Core is angular rubble with conchoidal fracture, although I suspect that there may be significant carbonate in this one, based on birefringence and calcareous tests still present.

1757.5 Negative 15. Same as above, plane polarized transmitted light (The stage rotated a little between frames).