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|Title:||Carbonate microfacies, depositional models and diagenesis of the Middle Devonian in Illinois, eastern Iowa and Missouri|
|Author(s):||Kocken, Roger James|
|Doctoral Committee Chair(s):||Carozzi, Albert V.|
|Department / Program:||Paleontology|
|Degree Granting Institution:||University of Illinois at Urbana-Champaign|
|Abstract:||The Middle Devonian Wapsipinicon Formation, Cedar Valley Limestone, Grand Tower Limestone and Lingle Formation in Illinois, eastern Iowa and Missouri were studied from ten field sections and four cores. Detailed petrographic analysis of almost 2,000 thin sections resulted in the recognition of twelve normal marine and twelve hypersaline microfacies. The vertical succession and statistical analysis of microfacies permitted recognition of four ideal shallowing-upward sequences which were converted into horizontal depositional models.
Model 1 represents the normal marine Grand Tower Limestone and Lingle Formation that occur south of the Sangamon Arch. It is a carbonate ramp with a quartz beach. Model 2 represent the normal marine Cedar Valley Limestone north of the Sangamon Arch. It consists, in an offshore direction of an intertidal flat, ecologically zoned lagoon, stromatoporoid buildup, slope and basinal environments. Model 3 represents the basal members of the Wapsipinicon Formation. It is a partly anoxic hypersaline environment consisting of a quartz beach, evaporitic flat, stromatolitic ridge, and an anoxic lagoon. Model 4 is a hypersaline environment with an inner lagoon and is applicable to parts of the Wapsipinicon Formation, Geneva Dolomite and Cedar Valley Limestone. This model consists of a quartz beach, evaporitic flat, inner lagoon, stromatolitic ridge, and an outer lagoon.
Separate diagenetic evolutions were recognized for the normal marine and hypersaline microfacies. The normal marine microfacies display diagenetic features indicating a normal evolution starting with marine phreatic, and proceeding through, marine vadose, meteoric vadose, undersaturated meteoric phreatic, saturated meteoric phreatic, mixed marine-meteoric and ending with burial. Diagenesis of the hypersaline microfacies is dominated by early dolomitization and formation of collapse breccias. The diagenetic sequence for the hypersaline microfacies is marine phreatic, marine vadose-evaporitic, meteoric vadose, meteoric phreatic, mixed marine-meteoric and burial.
Thirteen cycles were recognized, which appear to correlate well with published Middle Devonian sea level curves and indicate that the Middle Devonian was a time of oscillating sea level rise.
|Rights Information:||Copyright 1989 Kocken, Roger James|
|Date Available in IDEALS:||2011-05-07|
|Identifier in Online Catalog:||AAI8924863|
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