Physical Sciences and Mathematics Commons^™

Book Review: Quaternary Geology And Geomorphology Of South America By C. Clapperton, William J. Wayne

Department of Earth and Atmospheric Sciences: Faculty Publications

Dr. Clapperton is to be commended for having taken on the monumental task of a review of the present state of knowledge of the Quaternary of the entire continent of South America. Quaternary Geology and Geomorphology of South America is a massive, interestingly written, but expensive volume that covers exactly what its title suggests. In spite of the paucity of information on many aspects of the Quaternary geology of this continent, which extends from north of the equator nearly to the Antarctic, the author has succeeded in reviewing and synthesizing most of the material that does exist. To do so …

Patterns Of Early Lake Ontogeny In Glacier Bay As Inferred From Diatom Assemblages, Sherilyn C. Fritz, Daniel R. Engstrom

Department of Earth and Atmospheric Sciences: Faculty Publications

We studied a series of recently formed lakes along a deglaciation chronosequence in Glacier Bay National Park to examine changes in water chemistry, primary production, and biotic composition that accompany the early ontogeny of north-temperate lakes. Successional trends in these freshwater ecosystems have been explored with a two-tiered approach that includes (1) the comparison of limnological conditions among lakes of known age and in different stages of primary catchment succession, and (2) the inference of water-chemistry trends in individual sites based on fossil diatom stratigraphy. This paper emphasizes the reconstruction of limnological trends from fossil diatom assemblages. The modem distribution …

Dissociation Quotients Of Succinic Acid In Aqueous Sodium Chloride Media To 225°C, Richard Kettler, Donald A. Palmer, David J. Wesolowski

Department of Earth and Atmospheric Sciences: Faculty Publications

The first and second molal dissociation quotients of succinic acid were measured potentiometrically with a hydrogen-electrode, concentration cell. These measurements were carried out from 0 to 225"C over 25 ° intervals at five ionic strengths ranging from 0.1 to 5.0 molal (NaCl). The dissociation quotients from this and two other studies were combined and treated with empirical equations to yield the following thermodynamic quantities for the first acid dissociation equilibrium at 25°C: logK_1a = -4.210±0.003; Δ H_1̊a = 2.9±0.2 kJ-mol ^{- 1} ; ΔS_1̊a = -71±1 J-mol ^{- 1} -K ^-1; and ΔC_p̊,1a = -98±3 …

Stratigraphy And Sediment Accumulation Patterns Of The Upper Cenozoic Pelagic Carbonate Caps Of Guyots In The Northwestern Pacific Ocean, David K. Watkins, Paul N. Pearson, Elisabetta Erba, Frank R. Rack, Isabella Premoli Silva, Horst W. Bohrmann, Julianna Fenner, Peter R.N. Hobbs

Department of Earth and Atmospheric Sciences: Faculty Publications

Many of the guyots of the Northwestern Pacific Ocean are capped by sequences of uncemented pelagic carbonate. Examination of three of these pelagic caps from Limalok, Lo-En, and Wodejebato guyots in the Marshall Islands indicates that sediment accumulation throughout the late Paleogene and late Cenozoic was characterized by episodes of deposition during the earliest Miocene, late early to early middle Miocene, late middle Miocene, mid-Pliocene, and Quaternary, separated by periods of little or no accumulation. The Miocene record consists of extensively winnowed foraminifer oozes, which suggest relatively energetic currents in the intermediate waters. The Pliocene and Quaternary sequences contain finer …

Cretaceous Calcareous Plankton Biostratigraphy Of Sites 872 Through 879, Elisabetta Erba, Isabella Premoli Silva, David K. Watkins

Department of Earth and Atmospheric Sciences: Faculty Publications

This paper documents the distribution of calcareous nannofossils and planktonic foraminifers in Cretaceous sequences recovered at Sites 872 through 879 drilled on guyots in the central and western Pacific Ocean during Leg 144. Calcareous plankton biostratigraphy allows us to obtain important biostratigraphic age constraints for the onset, development, and demise of shallow-water sedimentation on these guyots.

Site 872 on Lo-En Guyot is the only site at which shallow-water limestones were not recovered during Leg 144. Here, the oldest sediment consists of pelagic limestone infilling fractures within the volcanic substrate. Calcareous plankton biostratigraphy constrains the age of these sediments to Coniacian …

Impact Of Erosion, Mass Wasting, And Sedimentation On Human Activities In The Río Grande Basin, Jujuy Province, Argentina, Waldo Chayle, William J. Wayne

Department of Earth and Atmospheric Sciences: Faculty Publications

Nearly all dry mountainous regions are affected by severe erosion, floods, and debris flows during times of intense precipitation. The lithology, geologic structure, and climate in Jujuy Province, Argentina combine to place at serious risk the people who live along the Río Grande, the major river that drains the east side of the Cordillera Oriental and the west side of the Sierras Subandinas. Nearly all precipitation falls during summer (January–March) with little during the remainder of the year; most of the basin is semiarid to arid, although the southern end has a humid subtropical climate. Relief is great, as much …

19. Pedogenic Alteration Of Basalts Recovered During Leg 144, Mary Anne Holmes

Department of Earth and Atmospheric Sciences: Faculty Publications

Basalts erupted to form the atolls and guyots of the Western Pacific have been altered in various ways, ranging from hydrothermal alteration to subaerial weathering by meteoric waters in a tropical environment. Subaerial weathering has been moderate to extreme. Moderate subaerial weathering is expressed by dissolution or replacement of primary minerals (olivine, pyroxenes, plagioclase feldspar) and alteration of glassy or aphanitic matrix to clay minerals, goethite, and hematite. The clay minerals are kaolinite or a brown smectite. Kaolinite concentrations decrease downhole and smectite concentrations increase. Although primary minerals are generally not preserved, primary structures, such as vesicles (generally filled by …

Oldest Cretaceous Sequence, Giralia Anticline, Carnarvon Basin, Western Australia: Late Hauterivian-Barremian, S. Mcloughlin, D. W. Haig, J. Backhouse, Mary Anne Holmes, G. Ellis, J. A. Long, K. J. Mcnamara

Department of Earth and Atmospheric Sciences: Faculty Publications

Outcrop of the oldest Cretaceous sequence in the Giralia Anticline and the Giralia No. 1 well, penetrating the same sequence, are described and biostratigraphically assessed in detail. The Cretaceous rocks lie on an erosion surface cut into Permian strata. A 10 m thick basal sand unit, the Birdrong Sandstone, is overlain by 56 m of carbonaceous siltstone-mudstone (Muderong Shale). The Birdrong Sandstone in the anticline belongs to the Muderongia australis Zone of late Hauterivian-Barremian age, as does the lower part of the Muderong Shale. The age of the upper Muderong Shale is uncertain, as is the age of a 10 …

Dissociation Quotient Of Benzoic Acid In Aqueous Sodium Chloride Media To 250°C, Richard Kettler, David J. Wesolowski, Donald A. Palmer

Department of Earth and Atmospheric Sciences: Faculty Publications

The dissociation quotient of benzoic acid was determined potentiometrically in a concentration cell fitted with hydrogen electrodes. The hydrogen ion molality of benzoic acid/benzoate solutions was measured relative to a standard aqueous IiCI solution at seven temperatures from 5 to 250°C and at seven ionic strengths ranging from 0.1 to 5.0 molal (NaCI). The molal dissociation quotients and selected literature data were fitted in the isocoulombic (all anionic) form by a six-term equation. This treatment yielded the following thermodynamic quantities for the acid dissociation equilibrium at 25°C and 1 bar: log K_a = -4.206±0.006, ΔH_å=0.3±0.3 kJ-mol^{-1 …}

Initial Transgressive Phase Of Leg 144 Guyots: Evidence Of Extreme Sulfate Reduction, Bjørn Buchardt, Mary Anne Holmes

Department of Earth and Atmospheric Sciences: Faculty Publications

The initial transgressive phase at the Leg 144 Guyots is characterized by a typical association of sedimentary facies (from bottom to top): in situ weathered volcanic rocks; variegated clays, partly pyritic; gray clay, pyritic, homogeneous, or mottled; black clay, peaty, laminated, or bioturbated; and marine argillaceous limestone. Site 877 at Wodejebato Guyot represents the typical development of the initial transgressive phase. The black clay is rich in organic carbon (up to 40%) and sulfur (up to 25%). The organic matter is dominantly of terrestrial origin, but it has a significant marine, algal input. The variegated clays consist of a red, …

Campanian Dwarf Calcareous Nannofossils From Wodejebato Guyot, Elisabetta Erba, David K. Watkins, Jörg Mutterlose

Department of Earth and Atmospheric Sciences: Faculty Publications

Calcareous nannofossils occur in lagoonal sediments recovered from Sites 873, 874, and 877 drilled on Wodejebato Guyot in the central Pacific Ocean. Nannofloras are present only in a few layers, from which several smear slides were prepared. All the specimens were counted, and the relative abundance of taxa was computed as percentages. Assemblages are characterized by excellent preservation, very high diversity (= number of taxa), but extremely low abundance. Both diversity and abundance decrease from the inner perimeter ridge along the northern edge of the atoll (Sites 877 and 874) to the inner lagoon (Site 873), but the assemblage composition …

Chronostratigraphic Significance Of Cathodoluminescence Zoning In Syntaxial Cement: Mississippian Lake Valley Formation, New Mexico, Tracy D. Frank, Kuger C. Lohmann, William J. Meyers

Department of Earth and Atmospheric Sciences: Faculty Publications

Echinoderm-syntaxial cement crystals have been collected at several stratigraphic levels within the Lake Valley Formation, which is overlain by a major pre-Pennsylvanian subaerial exposure surface. The crystals were microsampled along growth bands, and yielded high-resolution elemental and isotopic information that record fluid evolution during their growth. Although cement crystals show little variation in cathodoluminescence character and bulk chemistry throughout the regional extent of the formation, intracrystalline patterns in minor element and stable isotope chemistry allow for the identification of several settings of cementation, including the marine phreatic, marine-meteoric mixing, and meteoric phreatic zones. When placed in a regional-stratigraphic context, crystal …

Cretaceous And Paleogene Manganese-Encrusted Hardgrounds From Central Pacific Guyots, David K. Watkins, Isabella Premoli Silva, Elisabetta Erba

Department of Earth and Atmospheric Sciences: Faculty Publications

Manganese-encrusted hardgrounds and associated sediments from four guyots in the western Pacific Ocean were investigated using lithostratigraphic and biostratigraphic examination of thin sections. Biostratigraphic data from manganese-encrusted hardgrounds constrain the age of platform drowning to early middle Eocene for Limalok Guyot, latest Maastrichtian to early Paleocene for Wodejebato Guyot, and middle late Albian for MIT Guyot. Microstratigraphic examination of the hardgrounds reveals a complex Cretaceous and Paleogene history of bioerosion, pelagic sediment accumulation, manganese encrustation, and phosphatization. Fourteen distinct episodes of pelagic sediment accumulation occurred, with five in the Cretaceous, three in the Paleocene, and seven in the Eocene. These …