Douglas W. Haywick

Foraminiferal paleobathymetry of Plio-Pleistocene cyclothemic sequences, Petane Group, New Zealand

Plio-Pleistocene strata of the Petane Group, central Hawkes Bay, New Zealand are composed of alternating fine-grained (silt) and coarse-grained formations (sand, graywacke gravel and coquina), that have resulted from glacio-eustatic sea-level changes. Nine depth-related foraminiferal associations are recognized within these cyclothemic strata, spanning the entire range of inner to outer shelf paleoenvironments

A lone biodetrital mound in the Chesterian (Carboniferous) of Alabama

Abstract A carbonate mound in the Chesterian Bangor Limestone of Lawrence County, Alabama, consists chiefly of packstone and grainstone dominated by echinoderm ossicles and fragments of fenestrate bryozoans. In-situ colonies of the rugose coral Caninia flaccida comprise about 8% of the mound by volume. The exposed portion of the mound is approximately 25 m wide, 1.6 m thick at the thickest point and roughly circular in plan. The mound developed on top of a shallow ooid shoal that had been cemented and stabilised during an earlier episode of sub-aerial exposure. Subsequent flooding of the exposed shoal surface permitted establishment of the mound biota. Lateral and vertical facies relationships suggest that the mound possessed about 45 cm of synoptic relief when fully developed. Rugose corals, fenestrate and ramose bryozoans, stalked echinoderms, and sessile soft-bodied organisms encrusted by foraminifera colonised the shoal, forming a mound. Baffling resulted in deposition of mixed-fossil packstone containing locally derived debris and coated grains from the surrounding sea floor. Strong currents within the mound are indicated by preferred orientation of corals and by coarse, commonly cross-stratified grainstone in channels between neighboring coral colonies. Corals are most abundant on the windward side of the mound, where they account for about 13% of the mound compared to 6–10% in the central part of the mound, and 2–4% on the leeward flank. Biodetrital mounds such as the one described here are uncommon in upper Paleozoic strata and previously unknown in the Bangor Limestone. Of 10 carbonate buildups we examined in the Bangor in Alabama and Tennessee, only one is a biodetrital mound. Two are rugose coral–microbial reefs, one is a coral biostrome, and six are dominated by microbialite. The Bangor shelf, previously interpreted as sedimentologically simple, appears to contain many small mounds of quite varied characteristics. Also, the discovery of a biodetrital mound in the Chesterian of Alabama suggests that there may be more kinds of upper Paleozoic mounds than commonly acknowledged.

Evidence of carpinus (betulaceae) in the late tertiary (pliocene) of alabama.

Carpinus is a common and widespread element of the modern North American forest vegetation, but its scant fossil record on the continent is perplexing, especially considering the abundant and relatively continuous record of the genus in the Tertiary of Europe and Asia. Despite earlier claims of Tertiary Carpinus remains, recent reviews have indicated that a definitive post-Eocene Tertiary record of the genus in North America is lacking. Therefore, it remains uncertain if Carpinus was present but left no clear fossil record or if the genus became extinct in North America and migrated back to the continent more recently. A reinvestigation of the Citronelle Formation paleoflora has yielded conclusive evidence for the presence of Carpinus in the Gulf Coastal Plain of Alabama during the Pliocene based upon the discovery of a nutlet bract. Carpinus bracts are distinctive and consist of a central bract fused basally with two lateral bractlets. This specimen provides proof of the existence of Carpinus on this continent by the Pliocene Epoch, and any future research on the biogeography of the genus must consider this as the earliest, post-Eocene record of the genus in North America based on unequivocal reproductive structures.

Diagenesis of polymineralic temperate limestones in a cyclothemic sedimentary succession, eastern North Island, New Zealand

Abstract Temperate carbonate petrofacies (calcarenite and coquina) in the Pliocene‐Pleistocene Petane Group of eastern North Island, New Zealand, are dominated by aragonite faunas consisting primarily of bivalves and gastropods. Unlike calcite‐dominated temperate limestones, these polymineralic carbonates have undergone extensive early diagenetic alteration including extensive calcite cementation induced by aragonite dissolution. Marine cementation (type 1: pore‐lining, bladed calcite) was isolated to biogenic pores. It predated glauconite and may have been precipitated as low‐magnesium calcite, possibly in marine phreatic environments during sea‐level transgressions. Four phases of calcite cement with varying but definitive degrees of meteoric influence occur in the Petane Group. Type 2 (ferroan scalenohedral calcite) was the initial pore‐filling cement and precipitated from reduced pore fluids in a phreatic environment, possibly during or soon after the transition from marine to meteoric diagenesis. Type 3 (moderately ferroan drusy) calcite and type 4 (non‐ferroan drusy) calcite were sequentially precipitated during meteoric conditions from pore waters that changed from reducing to oxidising. Type 5 (sinter) cements comprise several forms precipitated during vadose meteoric diagenesis, the final meteoric phase of alteration in the Petane Group. Ferroan calcite cementation of silt matrix in coquina limestones overlain by terrigenous silt (type 6: matrix cement) probably occurred simultaneously with type 2/3 pore‐filling phases. A similar ferroan to moderately ferroan to non‐ferroan suite of drusy calcite cements also lithified concretions in non‐carbonate (siliciclastic sand) facies in the Petane Group, but only after the onset of compaction. Extensive skeletal diagenesis (stabilisation of magnesium calcite allochems, dissolution/recrystallisation of aragonite) occurred during type 3 and 4 cementation phases. Diagenesis in the Petane Group was stratigraphically influenced and ultimately controlled by uplift. Alternating sequences of porous and non‐porous formations developed a stacked sequence of confined aquifers that forced carbonate diagenesis to operate laterally.

Overcoming Challenges of Teaching Earth History Classes for Teachers in a Rock-free, Urban Environment

Instructing university-level Earth history to future teachers is made all the more difficult when it is being done in an urban environment devoid of any local rock outcroppings. At the University of South Alabama, which is located along the rock-free central Gulf Coast, we have attempted to improve Earth history instruction to education majors by using a three-pronged approach: (1) designing a course specifically for students intending to become science teachers; (2) encouraging students to think “locally” when designing geological teaching activities and (3) offering future teachers relevant field excursions and directed research opportunities. Our main objective is to demonstrate to new science teachers that geology is all around them, regardless of their location. It is this philosophy that we wish them to communicate to their students in the public school system.

A biodetrital coral mound complex: Key to early diagenetic processes in the mississippian bangor limestone

The Bangor Limestone is a Mississippian (Chesterian) shallow marine carbonate formation exposed over a large portion of the Interior Low Plateaus province of northern Alabama. It is dominated by oolitic grainstone and skeletal wackestone and packstone, but in one outcrop near Moulton, Alabama, the Bangor contains a five m thick, 25 m wide, oolite-biodetrital mound-tidal flat succession. This sequence is interpreted as a 4th order sea level cycle.Four petrofacies (oolite, mound, skeletal and mudstone/dolomicrite) and four diagenetic phases (iron oxide, fibrous calcite cement, calcite spar cement and dolomite) are distinguished at the study site. Iron oxide, a minor component, stained and/or coated some ooids, intraclasts and skeletal components in the oolite petrofacies. Many of the allochems were stained prior to secondary cortical growth suggesting a short period of subaerial exposure during oolite sedimentation. The oolite petrofacies also contains minor amounts of fibrous calcite cement, a first generation marine cement, and rare infiltrated micrite that might represent a second phase of marine cement, or a first phase of meteoric cement (i.e., “vadose silt”) (Dunham 1969). Intergranular pore space in all four petrofacies is filled with up to three phases of meteoric calcite spar cement. The most complete record of meteoric cementation is preserved within coralline void spaces in the mound petrofacies and indicates precipitation in the following order: (1) non-ferroan scalenohedral spar, (2) ferroan drusy spar (0.1–0.4 wt% Fe2+) and (3) non-ferroan drusy spar. The first scalenohedral phase of meteoric cement is distributed throughout the oolite and mound petrofacies. The ferroan phase of meteoric,calcite is a void-filling cement that is abundant in the mound petrofacies and less common in the skeletal and mudstone/dolomicrite petrofacies. Non-ferroan drusy calcite is pervasive throughout the Bangor Limestone at the Moulton study site.Growth of the fourth diagenetic phase, dolomite, was the dominant event in the micrite/dolomicrite petrofacies, particularly just below an irregular surface overlain by a brecciated interval. The irregular surface is interpreted as an exposure surface. Three phases of dolomite occur below the exposure surface. The majority is finely crystalline, anhedral, and enriched in Si4+, criteria which support a supratidal or mixed hypersaline έteoric origin. Secondary phases of coarser euhedral non-ferroan and ferroan dolomite are restricted to fenestrae and other voids in the micrite/dolomicrite petrofacies and were precipitated during subsequent meteoric diagenesis.Diagenesis of the Bangor Limestone at the Moulton outcrop was dominated by synsedimentary and very early meteoric processes driven by periods of subaerial exposure. Large voids within the mound petrofacies were particularly important, as they remained open long enough to record a more detailed early meteoric cement stratigraphy that might not be evident in Bangor Limestone outcrops elsewhere in Alabama.

Undergraduate Research Projects in Atomic Collisions and Gamma‐ray Spectroscopy

Research projects at University of South Alabama, an undergraduate physics department, have employed a 150‐kV Cockcroft‐Walton accelerator for atomic collisions and sodium‐iodide and high‐purity germanium detectors for gamma‐ray studies. The atomic collision experiments dealt with electron capture and electron loss in collisions of protons and hydrogen atoms with hydrocarbon molecules. Gamma‐ray studies with NaI scintillators determined the potassium content of food using 40K gamma‐rays. Environmental studies of river sedimentation use a HPGe detector to determine 137Cs and 210Pb content. Students learn the physics of the interactions of ionizing radiation with matter, while acquiring a familiarity with high‐vacuum technique, electronics, data acquisition and analysis, and reporting of results.