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Procedure for geometrical analysis (view source)
Revision as of 15:40, 29 August 2014
, 15:40, 29 August 2014→Example of unconformity analysis
Cores and samples should be examined for evidence of unconformities. These unconformity surfaces should then be calibrated to logs. Logs can then be used to correlate the surfaces to seismic and to other wells. [[:file:exploring-for-stratigraphic-traps_fig21-16.png|Figure 1]]<ref name=ch21r12>DolsonMuller, D., S., 1994, Stratigraphic evolution of the Lower Cretaceous Dakota Group, Western Interior, U., S., A., in Caputo, M., V., Peterson, J., A., Franczyk, K., J., eds., Mesozoic Systems of the Rocky Mountain Region, U., S., A.: SEPM Rocky Mountain Section, p. 441–456.</ref> shows an example of calibrating unconformity evidence from cores to logs. The Lower Cretaceous Cutbank Sandstone unconformably overlies the Jurassic Swift Formation. A major lowstand surface of erosion (LSE) is shown at [[depth::2957 ft]] (901 m) and was identified using the following criteria:
Cores and samples should be examined for evidence of unconformities. These unconformity surfaces should then be calibrated to logs. Logs can then be used to correlate the surfaces to seismic and to other wells. [[:file:exploring-for-stratigraphic-traps_fig21-16.png|Figure 1]]<ref name=ch21r12>DolsonMuller, D., S., 1994, Stratigraphic evolution of the Lower Cretaceous Dakota Group, Western Interior, U., S., A., in Caputo, M., V., Peterson, J., A., Franczyk, K., J., eds., Mesozoic Systems of the Rocky Mountain Region, U., S., A.: SEPM Rocky Mountain Section, p. 441–456.</ref> shows an example of calibrating unconformity evidence from cores to logs. The Lower Cretaceous Cutbank Sandstone unconformably overlies the Jurassic Swift Formation. A major lowstand surface of erosion (LSE) is shown at [[depth::2957 ft]] (901 m) and was identified using the following criteria:
* Missing [[biostratigraphy|biostratigraphic]] horizons
* Missing [[Biostratigraphic correlation and age determination|biostratigraphic]] horizons
* Subaerial (weathered) zone beneath a channel
* Subaerial (weathered) zone beneath a channel
* Facies omission (abrupt change from marine shale to a fluvial sandstone)
* Facies omission (abrupt change from marine shale to a fluvial sandstone)