Digital Commons Network^™

Textural And Compositional Evidence For Magma Mixing In The Evolution Of The Çamlıdere Volcanic Rocks (Galatean Volcanic Province), Central Anatolia, Turkey, Eli̇f Varol, Abi̇di̇n Temel, Alain Gourgaud

Turkish Journal of Earth Sciences

The Çamlıdere area, in the Galatean Volcanic Province (Ankara), Turkey, is composed of rhyolitic, andesitic, trachytic, dacitic and locally basaltic rocks. The older volcanic rocks in the studied area are rhyolitic and the younger ones basaltic. The phenocrysts from all the volcanic rocks exhibit some petrographic disequilibrium features such as: (a) coexistence of reversely, normally and oscillatory zoned sieved or unsieved plagioclase in the same rock; (b) wide compositional variation of An% in feldspar phenocrysts; (c) sieved, unsieved, normally and reversely zoned pyroxenes occur together in a single rock; (d) some orthopyroxene phenocrysts are surrounded by clinopyroxene; (e) reaction textures, …

Statistical Earthquake Frequency Analysis For Western Anatolia, Esi̇n Fi̇ruzan

Turkish Journal of Earth Sciences

In order to apply a statistical earthquake frequency analysis to western Anatolia, the area has been restricted within coordinates 36.50º-40º North and 26.00º-30.00º East. Data used in the analysis belong to the instrumental period from 1.1.1900 to 10.11.2006 (Ms ≥ 4.0). The earthquake record was assumed to be representative of longer periods and the possibility of clusters of seismicity or of extreme magnitude events were ignored. The study area has been divided into eight zones with different seismotectonic properties. All computations have been performed for these zones separately. The earthquake magnitude series is termed as the instantaneous peak over the …

Quaternary Calcrete Development In The Mersin Area, Southern Turkey, Muhsi̇n Eren, Selahatti̇n Kadi̇r, Zübeyde Hati̇poğlu, Murat Gül

Turkish Journal of Earth Sciences

Quaternary calcretes are widespread in the Mersin area and occur in a variety of forms. Several distinct calcrete profiles are recognized and subdivided into two major groups defined by mature and immature profiles. Mature calcrete profiles comprise a generally isolated calcrete horizon at the base and hard laminated crust at the top with rarely pisolithic crust in the uppermost part. The immature calcrete profiles consist mainly of an isolated calcrete horizon which is rarely overlain by a laminated crust. Calcrete forms show three main stages of development: (i) a mottled or plugged horizon, comprising isolated calcrete forms such as powdery, …

Relative Sea-Level Changes Of The Lower Cretaceous Deposits In The Chotts Area Of Southern Tunisia, Lazzez Marzouk, Mohamed Ben Youssef

Turkish Journal of Earth Sciences

A transition facies between evaporate and clay, carbonate and siliciclastic deposits occurs within the Lower Cretaceous of Southern Tunisia. The sedimentary deposits comprise four major transgressive-regressive sedimentary sequences with distinctive sabkha, tidal to shallow carbonate marine platform, and mixed siliciclastic ramp environments. Sedimentation rates, as well as thickness and facies changes were controlled by tectonic, climatic and eustatic factors. Transgression pulses encompassing the whole Late Hauterivian-Barremian, Early Aptian and Late Albian have controlled the basin infill. Evaporate and siliciclastic systems pass gradually to carbonate deposition in the Chotts area. Our sedimentation model helps to decipher the roles of tectonics and, …

A 700-Year History Of Groundwater Recharge In The Drylands Of Nw China, John B. Gates, W. Mike Edmunds, Jinzhu Ma, Paul R. Sheppard

Department of Earth and Atmospheric Sciences: Faculty Publications

A 700-year semi-quantitative history of diffuse groundwater recharge in the Badain Jaran Desert (Inner Mongolia) is proposed on the basis of solute data from multiple unsaturated zone groundwater profiles using mass balance of chloride to establish recharge rates and profile chronologies. Four relatively humid (1330–1430, 1500–1620, 1700–1780 and 1950– 1990) and three relatively arid phases (1430–1500, 1620–1700 and 1900–1950) are discernable across the profiles. The recharge history broadly reflects multidecadal to centurial timescale precipitation changes in the northern Tibetan Plateau and suggests that variations in East Asian Summer Monsoon intensity affect desert recharge rates. Uncertainties in the records owing to …

Stable Isotopes In Early Eocene Mammals As Indicators Of Forest Canopy Structure And Resource Partitioning, Ross Secord, Scott L. Wing, Amy Chew

Department of Earth and Atmospheric Sciences: Faculty Publications

The three dimensional structure of vegetation is an important component of ecosystems, yet it is difficult to reconstruct from the fossil record. Forests or woodlands prevailed at mid-latitudes in North America during the early Eocene but tree spacing and canopy structure are uncertain. Here we use stable carbon isotope values (δ¹³C) in early Eocene mammalian faunas to infer canopy structure. We compare δ¹³C values in two diverse fossil assemblages from the central Bighorn Basin to values predicted for mammals in a variety of open and closed habitats, based on modern floras and faunas. We conclude that …

Iron Ooid Beds Of The Carolinefjellet Formation, Spitsbergen, Norway, Jeremy Mutrux, Harmon D. Maher Jr., Robert Duncan Shuster

Geography and Geology Faculty Publications

Iron ooid beds are unusual deposits that have been linked to greenhouse conditions and the transgressive flooding of shallow shelves, and which were globally prevalent during certain periods. Within the marine, Aptian-Albian, Carolinefjellet Formation of Spitsbergen, chamosite ooids have been found within distinctive sandstone beds at six localities, and at a consistent stratigraphic position within the basal Dalkjegla Member. Distinctive characteristics include the iron ooids themselves, a coarser grain size, intercalation with silty siderites, grading, cross-beds indicating offshore or longshore transport, and a lack of burrowing. The enclosing sands display planar and hummocky crossstratification and abundant oscillation ripple marks, and …

The Evolution Of Travertine Masses In The Sivas Area (Central Turkey) And Their Relationships To Active Tectonics, Levent Mesci̇, Hali̇l Gürsoy, Orhan Tatar

Turkish Journal of Earth Sciences

Sıcak Çermik, Delikkaya and Sarıkaya are important travertine fields with active hot springs located 31 km west of Sivas. Based on their morphology, most of the travertines are classified as fissure-ridge travertines. Eroded sheet-type, terraced, and self-built channel types of travertine are also present at a few locations. Faults and fissures formed in the underlying İncesu Formation, and fissures developing in the fissure-ridge travertines are linked to one another. Tectonic deformation forming the fissure-ridge travertines resulted from NE-SW extension associated with a NW-SE compressional regime related to the Central Anatolian Thrust Belt and Sivas Backthrust. U/Th series age dating results …

Petrogenesis Of The Kösedağ Pluton, Suşehri-Ne Sivas, East-Central Pontides, Turkey, Durmuş Boztuğ

Turkish Journal of Earth Sciences

The Kösedağ syenite crops out as a shallow-seated pluton within the Eocene volcano-sedimentary rocks and is unconformably overlain by Lower Miocene limestones in the Suşehri-NE Sivas region, east-central Pontides. It consists of syenites and quartz syenites with a phaneritic, porphyritic texture characterized by K-feldspar megacrysts set in a coarse- to medium-grained groundmass comprising K-feldspar, plagioclase, clinopyroxene, amphibole, biotite and quartz. Major element geochemistry data reveal a high-K, alkaline, metaluminous to slightly peraluminous character, with a low Aluminum Saturation Index (ASI) value. The main solidification process, which modified the composition of magma during crystallization, was fractional crystallization, in which syenites solidified …

Palynostratigraphic, Palaeovegetational And Palaeoclimatic Investigations On The Miocene Deposits In Central Anatolia (Çorum Region And Sivas Basin), Mi̇ne Sezgül Kayseri̇, Funda Akgün

Turkish Journal of Earth Sciences

Palynostratigraphy of the Neogene coal-bearing sediments in the Çorum region and Sivas Basin has been determined, and three sporomorph associations have been defined. Sporomorph association A is described from the Samsun-Havza region and is of latest Burdigalian age. Sporomorph association B is described from the Çorum region and Sivas Basin and is of early-middle Serravalian age. Sporomorph association C is described from the Sivas-Vasıltepe region and is of earliest Tortonian age. Sporomorph association A indicates warm subtropical climatic conditions and the Coexistence Approach (CA) results are: mean annual temperature (MAT) 19 °C, mean annual coldest month (CMT) 9.75 °C, mean …

Platinum-Group Minerals (Pgm) And Other Solid Inclusions In The Elbistan-Kahramanmaraş Mantle-Hosted Ophiolitic Chromitites, South-Eastern Turkey: Their Petrogenetic Significance, İbrahi̇m Uysal

Turkish Journal of Earth Sciences

The Elbistan-Kahramanmaraş podiform ophiolitic chromitites, in southeastern Turkey, contain abundant primary inclusions of platinum-group minerals (PGM), base-metals sulphides (BMS) and silicates. These inclusions are very small, generally less than 15 microns in size, and mostly occur in chromian spinel. The following PGM have been recognized: laurite, iridium, irarsite, ruarsite and several unidentified PGE phases. Millerite, pentlandite, bornite, digenite, chalcopyrite and betekhtinite are the BMS that have been identified. Mg-rich hornblende, accompanied by rare olivine, clinopyroxene and phlogopite, are the most abundant silicate inclusions. Most of the PGM, BMS and silicate inclusions are considered primary, i.e. formed during the high temperature …

Quantifying Vertical Mixing In Estuaries, W. Rockwell Geyer, Malcolm E. Scully, David K. Ralston

CCPO Publications

Estuarine turbulence is notable in that both the dissipation rate and the buoyancy frequency extend to much higher values than in other natural environments. The high dissipation rates lead to a distinct inertial subrange in the velocity and scalar spectra, which can be exploited for quantifying the turbulence quantities. However, high buoyancy frequencies lead to small Ozmidov scales, which require high sampling rates and small spatial aperture to resolve the turbulent fluxes. A set of observations in a highly stratified estuary demonstrate the effectiveness of a vessel-mounted turbulence array for resolving turbulent processes, and for relating the turbulence to the …

Age And Structure Of The San Jacinto And San Felipe Fault Zones, And Their Lifetime Slip Rates, Susanne U. Janecke, R. J. Dorsey, B. Belgarde

Geosciences Faculty Publications

No abstract provided.

The Balancing Act, David Weaver

Conference papers and presentations

Nutrient management is as much a global issue as a local one with a balance required between economics and environment, inherent biological limitations and expectations of nutrient use efficiency, and traditional fertiliser practices and actual enterprise nutrient requirements. The concept of nutrient balance depends on context and scale. Nutrient balance can be considered at a global scale, where issues of nutrient stocks, cycles, depletion and transfer of a particular element are important. For a single farm enterprise, nutrient balance might be considered in terms of phosphorus (P) inputs into and outputs from the enterprise. This is commonly known as a …

Reclamation Of Saline Soils Through Revegetation In Australia: Plants, Processes And People, Edward G. Barrett-Lennard

Conference papers and presentations

Secondary salinity (salinity induced by human activity) is a major world problem. Hydrological imbalances in landscapes cause watertables to rise, drawing salt from deeper in the soil profile to the soil surface, where the combined stresses of salinity and waterlogging threaten the growth of crops and pastures. The reversal of salinity by the broad‐scale reintroduction of perennial plants back into landscapes may not be economically feasible, but watertables may be at least partly directly drawn‐down by the grow th of salt tolerant plants (halophytes) on saltland . This review summarises data from Australia in which the water use by perennial …

Geology Of Rum Cay, Bahamas: A Field Trip Guide, John E. Mylroie, James L. Carew, H. Allen Curran, Jonathan B. Martin, Thomas A. Rothfus, Neil E. Sealey, Fredrick D. Siewers

Geosciences: Faculty Publications

See other Smith authored Field Trip Guides of Gerace Research Centre.

Late Quaternary Geochronologic, Stratigraphic, And Sedimentologic Framework Of The Trinity River Incised Valley: East Texas Coast, Matthew Gene Garvin

LSU Master's Theses

Optically stimulated luminescence dates from the last glacial period falling–stage and lowstand Deweyville deposits along the Trinity River valley in Texas provided insight to their timing of deposition and allogenic controls on fluvial processes. Three distinguishable periods of incision and lateral channelbelt migration were the effect of both lowered sea levels and climate controlling factors within the drainage basin. Valley widening and deposition of the High, Middle, and Low Deweyville units were constructed and subsequently preserved as fluvial terraces during oxygen isotope stages (OIS) 3 through 2, from 65–32.5 ka, 32.5–23 ka, and 23–16 ka respectively. Although numerous workers using …

Deciphering Controls On Polyphase Intraplate Deformation In The Ertomiao Region, Lang Shan, North-Central China, Michael Blevins

LSU Master's Theses

The Ertomiao region of the Lang Shan, China, is located approximately 700 km west of Beijing, in the north-central portion of the North China block. This area is characterized by multiple periods of deformation, including periods of extension and contraction, spanning from Permian through Cenozoic time. This setting provides the structural relationships necessary to decipher the controls of polyphase crustal deformation. During fieldwork key structural observations and crosscutting relationships were established. Beginning with a period of contraction, northeast striking post Jurassic, pre Early Cretaceous (123 ma) thrust faults place Precambrian gneiss (unit PCB) onto Jurassic/Cretaceous sandstone and conglomerate (unit Jr/K). …

Middle Crustal Ductile Deformation Patterns In Southern Tibet: Insights From Vorticity Studies In Mabja Dome, Jackie Langille

All Master's Theses

Mabja Dome, southern Tibet, exposes mid-crustal rocks proposed to have originated from a southward flowing mid-crustal channel. Kinematic, mean kinematic vorticity (Wm), and metamorphic petrography analyses on these mid-crustal rocks were performed to test this hypothesis. Kinematic indicators show a transition with structural depth from top-north and top-south shear to solely top-south shear. Along the northernmost transects, Wm in schists and orthogneisses range from 0.52–0.84 (63–36% pure shear). Wm for quartzites ranges from 0.9–0.99 (27–1% pure shear). Deformation temperatures increase from ~450 °C in the chloritoid-zone to ~700 °C in the sillimanite-zone and were recorded between ~35–16 Ma. These patterns …

Energy Budget Analysis Of Slow-Slip Tremor Events Along The Cascadia Subduction Zone Using Continuous Gps Array Data, James Steven Chapman

All Master's Theses

Seismic hazards poised to cities by subduction zones are strongly controlled by fault slip along the deeper extent of the two plate interaction closest to population densities. In Cascadia, where Mw=9 size events are known to occur from a variety of sources, modeling of leveling data has suggested that the region of maximum slip lies well offshore and diminishes rapidly inland. However, over two dozen slow slip distributions have been imaged using Global Positioning System (GPS) along the lower reaches of the northern Cascadia locked zone between 30 and 40 km in depth. Averaged over many episodic tremor and slip …

Petrogenetic Processes Characterizing The Mount Bachelor, Oregon Magmatic System: Open- Versus Closed-System Processes, Sara Elizabeth Johnson

All Master's Theses

Mount Bachelor volcanic chain (MBVC), located in central Oregon, is one of the larger basalt and basaltic-andesite edifices in central Oregon. Preliminary studies have defined how eruptions have changed composition with time, but a detailed assessment of magma chamber processes has not been conducted. To gain a more thorough understanding of the magmatic processes that have contributed to the observed compositional evolution, this study focuses on one of four eruptive episodes, specifically episode III, the most voluminous episode of the four. Magmatic processes are assessed by focusing on both whole-rock and single crystal data.

The geochemistry and textural diversity of …

Comparison Of Landslides And Their Related Outburst Flood Deposits, Owyhee River, Southeastern Oregon, Shannon Marian Othus

All Master's Theses

Numerous landslides have entered the Owyhee River canyon north of Rome, Oregon. As the river flows through different lithologic units, the style of mass wasting changes from large slump events and small rock falls to large earthflows. The change in mechanism of mass wasting from upstream to downstream seems to depend on several factors: (1) the ratio of the basalt cap to the exposed underlying sediments, (2) the composition of underlying sediments, (3) the canyon geometry, and (4) the extent and frequency of mass wasting. All three mechanisms of mass wasting have the ability to block the river channel and …

The 2004 And 1861 Tsunami Deposits On Simeulue Island, Western Sumatra, Katherine Frances Whitlow

All Master's Theses

Megathrust earthquakes and associated tsunamis along the subduction zone along western Sumatra represent a significant seismic hazard that is not well understood. I present the results of mapping, paleoseimologic, and geochronologic studies of tsunami deposits exposed on Simeulue Island, western Sumatra, to document the timing of past tsunamis. Three field sites were targeted to conduct these studies: Inor, Busong Bay, and Langi Bay. Stratigraphic relationships, geochronologic data, and grain size analyses from these field sites show evidence of a tsunami that occurred in 1861 following a Mw ~8.5 earthquake. A wood fragment collected from an excavation at Inor yielded an …

Palaeoecology Of Coal-Bearing Eocene Sediments In Central Anatolia (Turkey) Based On Quantitative Palynological Data, M. Serkan Akki̇raz, Mi̇ne Sezgül Kayseri̇, Funda Akgün

Turkish Journal of Earth Sciences

In this study, the lignite-bearing Yoncalı formation between Yozgat and Sorgun, in central Anatolia has been palynologically examined. Based on 37 outcrop samples, quantitative palynological studies recognized 64 genera and 136 palynoflora species in the palynological assemblage, which indicated a Middle-?Late Eocene age. This paper also presents a quantitative palaeovegetation and palaeoclimate reconstruction for the Middle-?Upper Eocene coal occurrences of Central Anatolia on the basis of palynomorph assemblages. The diversified floral and ecological characteristics of the pollen taxa indicates that the Middle-?Upper Eocene formations in central Anatolia were characterized by the presence of a complex mangrove swamp with contributions by …

Hydrologic Response To Extreme Warm And Cold Summers In The Mcmurdo Dry Valleys, East Antarctica, Peter T. Doran, Christopher P. Mckay, Andrew G. Fountain, Thomas H. Nylen, Diane M. Mcknight, Chris Jaros, John E. Barrett

Geography Faculty Publications and Presentations

The meteorological characteristics and hydrological response of an extreme warm, and cold summer in the McMurdo Dry Valleys are compared. The driver behind the warmer summer conditions was the occurrence of down-valley winds, which were not present during the colder summer. Occurrence of the summer down-valley winds coincided with lower than typical mean sea level pressure in the Ross Sea region. There was no significant difference in the amount of solar radiation received during the two summers. Compared to the cold summer, glaciological and hydrological response to the warm summer in Taylor Valley included significant glacier mass loss, and 3- …

Characterization Of The Lucinid Bivalve-Bacteria Symbiotic System: The Significance Of The Geochemical Habitat On Bacterial Symbiont Diversity And Phylogeny, Angela Marissa Green-Garcia

LSU Master's Theses

Extensive characterization of a single lucinid bivalve habitat was conducted to characterize the relationship between host bivalve and thiotrophic bacterial endosymbionts. For lucinids, the ecological and evolutionary relationships between hosts and endosymbionts are poorly understood. Reconstructing the evolutionary history of lucinid endosymbiosis, and the geologic significance of the association, has been hampered by insufficient knowledge of endosymbiont ecology and taxonomic diversity. Host organisms (Lucinisca nassula and Phacoides pectinatus) were collected from Cedar Keys, Florida, within the top 15-20 cm of the sediment in sea grass beds. PCR amplification and sequencing of bacterial 16S rRNA genes from lucinid gills and sediment …

Komatiitic Flows Of The Pioneer Ultramafic Complex Of The 3.3ga Weltevreden Formation, Barberton Greenstone Belt, South Africa: Stratigraphy, Petrology, And Geochemistry, Marc Romain Cooper

LSU Master's Theses

The 3.29 Ga Pioneer Ultramafic Complex (WPC) is a 1 km thick east-northeast trending tilted (90° dip) section of layered ultramafic rock in the Weltevreden Formation in the west-northwest region of the Barberton Greenstone Belt (BGB). It was originally interpreted as an intrusive complex with slaty zones that have a linear horizontal fabric produced by shear. However, a recent study identifies these slaty zones as komatiitic tuffs and attributes their horizontal fabric to plane and cross bedding. The present study suggests the non-slaty zones are extrusive komatiitic flows with abundant pyroxene spinifex tops, normal volcanic textures and crystal sizes, and …

Long-Term Subsidence And Compaction Rates: A New Model For The Michoud Area, South Louisiana, Clint H. Edrington

LSU Master's Theses

This study examined the stratigraphic record of the Michoud area in East New Orleans, Louisiana to address questions concerning the magnitude of, and processes leading to land-surface subsidence. The hypotheses under review are based on recent geodetic studies, which challenge the widely held position that modern subsidence is primarily a function of shallow sediment compaction. Testing these hypotheses involved constructing a structural cross section of the Michoud area using well logs, chronostratigraphic data, and fault picks, so as to evaluate differential motion along specific faults through time. Employing ages and corrected depths for three key subsurface horizons, long-term (Middle Miocene …

Turbulent Lifestyle: Microbial Mats On Earth’S Sandy Beaches—Today And 3 Billion Years Ago, Nora Noffke

OES Faculty Publications

Archean Earth history is very difficult to reconstruct. Until recently, only bacterial cells preserved in chert, microborings, and stromatolites provided the few clues to ancient life. Now, siliciclastic “microbially induced sedimentary structures” (MISS) are adding to our knowledge of both past life and paleoenvironments. MISS rise from the interaction of photoautotrophic microbial mats with physical sediment dynamics in siliciclastic, shallow-marine settings. Archean MISS can be understood through observations of living microbial mats and modern biotic-physical sedimentary processes. Such geobiological studies are key to the interpretation of the early evolution of prokaryotes. For example, the 2.9 Ga Pongola Supergroup, South Africa, …

The Effect Of Particles On Creep Rate And Microstructures Of Granular Ice, Min Song, Ian Baker, David M. Cole

Dartmouth Scholarship

The microstructures of particle-free granular freshwater ice and ice containing 1 wt.% of 50 ± 10 mm uniformly distributed particles were investigated before and after compressive creep to ∼10% strain with stresses of 1.45 MPa at −10°C and 0.4 MPa at −5°C. Creep rates of particle-containing ice were always higher than those of particle-free ice. For an initial stress of 1.45 MPa at −10°C, dynamic recrystallization occurred with new grains nucleating and growing along grain boundaries for both sets of specimens, and the ice with particles showed a higher nucleation rate. Under creep with an initial stress of 0.4 MPa …