Changes

==Diagenesis related to longterm cycles==

==Diagenesis related to longterm cycles==

Major unconformities that form as a result of uplift or third-order sea level lowstand can cause extensive diagenesis. In humid regions diagenesis can extend downdip for many miles and down section for hundreds to thousands of feet..<ref name=ch09r50>Read, J., F., Horbury, A., D., 1993, Eustatic and tectonic controls on porosity evolution beneath sequence-bounding unconformities and parasequence disconformities on carbonate platforms, in Horbury, A., D., Robinson, A., G., eds., Diagenesis and Basin Development: AAPG Studies in Geology 36, p. 155–197.</ref> Early down-section water flow is diffusive, mainly moving through intergranular pores. Later, down-section water movement becomes dominated by conduit flow. The change in flow character is a result of plugging intergranular pores and leaching that widens joints and turns vugs into caves.

Major unconformities that form as a result of uplift or third-order sea level lowstand can cause extensive diagenesis. In humid regions diagenesis can extend downdip for many miles and down section for hundreds to thousands of feet.<ref name=ch09r50>Read, J., F., Horbury, A., D., 1993, [http://archives.datapages.com/data/specpubs/resmi1/data/a067/a067/0001/0150/0155.htm Eustatic and tectonic controls on porosity evolution beneath sequence-bounding unconformities and parasequence disconformities on carbonate platforms], in Horbury, A., D., Robinson, A., G., eds., Diagenesis and Basin Development: AAPG Studies in Geology 36, p. 155–197.</ref> Early down-section water flow is diffusive, mainly moving through intergranular pores. Later, down-section water movement becomes dominated by conduit flow. The change in flow character is a result of plugging intergranular pores and leaching that widens joints and turns vugs into caves.

Reservoirs associated with long-term karsting tend to be highly compartmentalized<ref name=ch09r50 /> Vadose karst reservoirs tend to be of poor quality contrasted with phreatic reservoirs, which tend to be of high quality (Richard Fritz, personal communication). The amount of karstification decreases with decreasing rainfall. In very arid regions there may be relatively little diagenesis during emergence.

Reservoirs associated with long-term karsting tend to be highly compartmentalized<ref name=ch09r50 /> Vadose karst reservoirs tend to be of poor quality contrasted with phreatic reservoirs, which tend to be of high quality (Richard Fritz, personal communication). The amount of karstification decreases with decreasing rainfall. In very arid regions there may be relatively little diagenesis during emergence.