Geology (Stratigraphy) Stratigraphy Practical 2 (Term Week

Geology (Stratigraphy)

STRATIGRAPHY PRACTICAL 2 (Term Week 11)

Match the layers based on the changes in gamma readings

Kezza -1: 75m Fine rounded sands with minor silts

220-327m Quartzofelspathic sands

550-1000m Intermixed fine sands and silts

Kezza -- 2 50-150m Smectite-rich greenish marine clays with minor sands

150-300m Angular medium quartzofelspathic sands

350-600m Medium semi-rounded to angular sands

600-800m (terminal depth) Igneous basement

Kezza -- 3 0-100m Coarse poorly sorted sands; Fine sands and silts

100-400m Smectite and illite shale with some silts and thin fine sand beds

400m 530m Medium moderatel sorted sands with significant feldspar grains

530m 660m Coal; Medium sands

660-1000 Coal; Medium sands, Reefal carbonates; (terminal depth) Igneous basement

Kezza -- 4 0-200m Medium-coarse fluvio-deltaic sands

200-360m Fine sands with minor silt/clay interbeds

360-660m Marine shale with minor sand and silt interbeds

66-800m Medium singular sands

800-950m Coal; Quartzofelspathic sands

950-1246m Coal; Medium semi-round sands; (terminal depth) Felsic intrusives

Kezza -- 5 0-350m Course angular sands; Medium well sorted sands with some silts/clays

350-700m Well-sorted fine medium sands with some silts; Illite-rich claystone

700-1000m Illite claystone; Medium angular quartzofelspathic sands; coal

2.) Suggest why there is a change in gamma radiation within the Kezza rocks

Kezza 1 -- 5 is evidence of increasing meters in layer size of coarse sand, and sand silts. Prolonged exposure to gamma rays will create layers of sand and sand silts as evidenced by the Kezza rocks. The change of radiation within the rocks occurs in spikes as well as marginal increases followed by plateaus, followed with marginal increase(s) and is likely due to shifts in the rock surface and subsurface, creating deviations in the layers and pockets of increased gamma ray exposure.

3.) Why are some areas more "blocky/spikey" than others.

Some areas display more gamma ray activity than others due to the level of exposure of the sediment layer to the sun's gamma ray. These blocky/spikey areas do reflect the level of gamma ray emitted and the relative level of exposure and absorption of the ray.

4.) Why are some peaks more positive and some peaks more negative.