Mineralogical and chemical analysis of the Castle Hayne aquifer in east-central North Carolina / by Delynda Leigh Tolen Mehlhop.
| Author/creator | Mehlhop, Delynda Leigh Tolen author. |
| Other author | Woods, Terri L., degree supervisor. |
| Other author | East Carolina University. Department of Geology. |
| Format | Theses and dissertations |
| Production | 1998. |
| Description | viii, 96 leaves : illustrations (some color), maps ; 28 cm |
| Supplemental Content | Access via ScholarShip |
| Subjects |
| Summary | The Castle Hayne Aquifer System (CHAS) is one of the most extensively developed aquifers in North Carolina; however, little is known about how its lithology, mineralogy and mineral chemistry vary in the study area. Seventy-seven samples from six wells penetrating the CHAS were analyzed using petrography. X-ray Diffraction and Energy Dispersive X-ray to determine lithology, mineralogy, bioclast diversity and mineral chemistry. The CHAS is a biomicrite with quartz sand, glauconite, dolomite, apatite and lesser amounts of pyrite and aluminosilicates. Moldic porosity is high due to dissolution of bioclasts. Most samples are dominated by mollusks and echinoderm fragments, however brachiopods, bryozoans, and foraminifera are also present. Carbonates consist of nearly pure CaC03, but several samples contain variable amounts of MgCO3. Glauconite, the dominant clay mineral is most abundant at the base of the CHAS. It occurs as well-rounded peloids and occasionally as infill of skeletal bryozoan grains. Glauconite contains variable amounts of Fe203, AI2O3, MgO, and K2O. Changes in concentrations of Fe, Al, and Mg in the octahedral site reveal that Fe and A1 are inversely related to one another, while Mg remains reasonably constant. Fe concentration is much higher in peloids than in the infill material. Phosphate minerals appear at various depths in four of the sampled wells. They are hydroxy-, fluor-, or carbonate- apatites, and do not contain appreciable CF. Samples from four locations contain aluminosilicates; possibly Na-rich feldspars or zeolites. An iron sulfide mineral is present in three wells. Bioclast assemblages, lithology, and mineralogy support middle to outer shelf environment of deposition for the CHAS. The southwest region was closer to shore with shallower, more agitated water, indicated by the presence of more bioclasts and quartz sand and less glauconite. The northeast region was further offshore in deeper water on the shelf, indicated by the presence of more micrite. Vertical changes in the mineral chemistry of glauconite provide additional support for the placement of the upper and lower boundary. The geochemical and water chemistry data will help establish the most important controls on the potability of groundwater from the CHAS. |
| General note | Submitted to the faculty of the Department of Geology. |
| General note | Advisor: Terri L. Woods |
| Dissertation note | M.S. East Carolina University 1998 |
| Bibliography note | Includes bibliographical references (leaves 74-83). |
| Genre/form | dissertations. |
| Genre/form | Academic theses. |
| Genre/form | Academic theses. |
| Genre/form | Thèses et écrits académiques. |
Availability
| Library | Location | Call Number | Status | Item Actions |
|---|---|---|---|---|
| Joyner | University Archives | ASK AT SPECIAL COLLECTIONS DESK | ✔ Available | Request Material |
| Electronic Resources | Access Content Online | ✔ Available |