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Nature and Evolution of Deep Water Carbonate Drifts in the past 3 Million years, Inner Sea of the Maldives Archipelago, Equatorial Indian OceanLopez, Karem 24 July 2013 (has links)
The Maldives atolls, the very top of one of the largest modern carbonate platforms, occupy the central and largest part of the Chagos-Laccadives ridge located in the equatorial Indian Ocean. In the central part of the archipelago, the large atolls form two parallel north-south relatively continuous chains surrounding an internal basin, the Inner Sea, with water depths not exceeding 550 m. The Maldives carbonate system, uniquely evolved through a combination of global sea level fluctuations, subsiding history, and more regional seasonally varying monsoon circulation. Although the long-term evolution of this system is relatively well-established, the understanding of the detailed evolution of the Maldives carbonate edifice in the last 5 million years has remained limited. The latest phase of its stratigraphic evolution is explained by a shift from a well-developed Miocene-Pliocene progradational pattern to a mostly late Pliocene-Quaternary aggradational depositional signature. This last aggradation phase, forming the atolls the way we know them today, consists of stacked inner neritic limestone sequences, separated by a series of exposure horizons. The succesive periods of atoll exposure and re-flooding are recorded in the Inner Sea by late Pliocene-Quaternary glacial/interglacial clearly cyclic deposition of periplatform oozes. This cyclic sedimentary pattern also appears in the internal prograding geometry of carbonate drifts in the Inner Sea. A200 m-thick deep carbonate sediment drift was first observed on a Shell E-W seismic line north of Gaafaru Falhu atoll in the NE corner of the Maldives Inner Sea, in a range of water depths from ~300 to 500 m. During the NEOMA 2007 research cruise on the RV Meteor lead by Universität Hamburg, the deep water sandy drift in the area north of Gaafaru Falhu atoll and an adjacent deeper muddy drift was extensively surveyed via 12 kHz multibeam bathymetry, a 4 kHz sub bottom profiler (Atlas Hydrographics), multi channel high resolution seismics, and three box and piston cores. My study focuses on understanding the Plio-Quaternary overall evolution of the set of adjacent sandy and muddy drifts, just north of Gaafaru Falhu Atoll. The sandy and muddy drift interconnected internal geometries observed in the available seismic data sets are integrated into a sequence stratigraphic framework. Analyses of two piston cores collected from the upper part of the muddy drift and a box core from the top of the sandy drift determine the overall downcore lithology variations and made possible the development of high-resolution chrono and cyclo-stratigraphies. In the muddy drift periplatform sequence, downcore cyclic variations in, (1) sediment coarse fraction, (2) Sr counts as proxy for atoll-derived fine aragonite, (3) planktic foraminifer oxygen stable isotope composition, in addition to carbonate preservation and biostratigraphic markers, were determined. These downcore lithologic and geochemical variations in the muddy drift were tied to the seismic lines imaging the sandy-muddy drifts to resolve the timing of the carbonate sandy drift establishment and its overall evolution. Based on this aforementioned interpretation, the results of my research document the nature and timing of the longer-term evolution of the sandy and muddy drifts over multiple glacial-interglacial sea level cycles in the last 3 million years. Once the timing of the drift was determined, the prograding internal architecture of the sandy drift was examined and interpreted in the context of the relatively well-established Plio-Pleistocene sea level fluctuations and the bottom current variations
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Lithological And Morphological Control On The Agricultural Terraces In Bozburun Peninsula, TurkeySatici, Selim 01 January 2013 (has links) (PDF)
This study is carried out in Bozburun Peninsula where agricultural terraces exist. The purpose of the study is to investigate the effect of lithology and morphology of the area on the distribution of terraces.
The data used in the study is composed of necessary analog and digital topographic maps and geological maps which are revised by field data. Morphological settings of the regions, where terraces were placed, are classified into three types as coastal, valley and karstic. The methodology of the study consists of the analysis of elevation and slope values of terraces and three main rock units (alluvium, clastics and limestone) in ten selected areas.
Results of the analysis suggest followings on the relationship between terraces and lithological/morphological features: 1) the units are ordered from lowest to highest values of elevation and slope as alluvium, terraces, clastics and limestone / 2) agricultural terraces were highly and inversely influenced by limestone among all rock units / 3) terraces are mostly built in alluvium and clastics. 4) low elevation and slope values are preferred for agricultural terracing / 5) three landform types (coastal, valley and karstic) have different patterns in elevation and slope values of rock types as well as terraces.
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Assessment Of Durability Criteria Of The Armourstones Used In Mersin And Kumkuyu Harbours Based On Their Site And Laboratory PerformancesErtas, Burcu 01 August 2006 (has links) (PDF)
Breakwaters are constructed in coastal areas to protect coastal engineering structures from wave actions. Due to economic reasons, natural stones (armourstone) are very frequently used for the constructions of the breakwaters.
Considering the functions of the stones at different zones of the breakwaters, various sizes with variable properties of the armourstones are used in breakwaters.Deterioration of armourstones with time in the form of abrasion and disintegration may end up with the damage of the engineering structures. Therefore, it is necessary to investigate the long-term performance and quality of the armourstones, which should be sound and durable.
In this thesis, the properties of four limestones taken from two quarries with a known site performances as armourstones in Mersin and Kumkuyu harbors are studied .The site performances and durability of the limestones are compared with the field measurements and laboratory works.
For this purpose, the material and mass properties of the limestones are studied. Thus, the information obtained is used to assess long-term durability of the armourstones. The long& / #8211 / term performaces of the Degirmenç / ayi and Tirtar upper level limestones are observed to be good whereas it is rather poor for the Tirtar middle and lower level limestones. Comparison between the predicted and observed durabilities of the armourstones indicated that CIRIA/CUR, RDId, RERS, and wet to dry strength ratio give better results based on their field
performances. However, the prediction of the durability of the limestones is poor in case RDIs, average pore diameter, and saturation coefficient are used.
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Sedimentological, Cyclostratigraphical And Sequence Stratigraphical Analysis Of Cretaceous Uzumlu Formation (nw Turkey)Keskinler, Salih Yigit 01 May 2007 (has links) (PDF)
High resolution sampling was performed along the Ü / zü / mlü / Formation exposed near the YeniceSihlar village of Mudurnu (Bolu). Field and thin-section analyses showed that the Ü / zü / mlü / Formation is composed of cm to m scale cycles of 4th and 5th order. The 4th order cycles are equivalencies of parasequences and have 0.4 Ma average duration. 5th order cycles are interpreted as episodic. Upper Albian (OAE1c or OAE1d) and Cenomanian/Turonian (OAE2) anoxic events are observed as black shale levels in the studied section. Position of black shale levels is interpreted using cyclostratigraphy and sequence stratigraphy. Four types of cycle are determined. A and B-type cycles are placed in transgressive and Highstand System Tract. C and D-type cycles are placed in Lowstand System Tract. Two type 3 and one type 1 sequence boundaries are recorded. The boundary between the Sogukç / am Limestone and the Ü / zü / mlü / Formation is interpreted as the first type 3 sequence boundary. The second one separates the Ü / zü / mlü / Formation and the Yenipazar Formation and is observed at the top of the section. Type 1 boundary is represented by a conglomeratic level in the middle of the succession. Provenance analysis of sandstones indicates that during the Cenomanian the source area changed from magmatic arc setting to continental setting.
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Fairy Chimney Development In Cappadocian Ignimbrites (central Anatolia, Turkey)Sayin, M. Naci 01 March 2008 (has links) (PDF)
The purpose of this study is to evaluate systematic fairy chimney development within Cappadocian ignimbrites. The first step in the sudy is to identify fairy chimney producing ignimbrites. Accordingly the fairy chimneys are formed within Kavak ignimbrite, at Kavak-Zelve transition, and within Zelve and Cemilkö / y ignimbrites. Field measurements are taken from the fairy chimneys to quantify the shape and the size. Slope of the selected areas are identified to investigate the most suitable topography.
Analysis have shown that fairy chimneys have basal diameters ranging from 9.7 to 13.7 m, with heights in the range from 8.41 to 21.73 m. The slopes of fairy chimneys are 60 to 70 degrees with a slight asymmetry towards the upslope. The chimneys are sligthy rounded due to the erosion in the slope direction. Distances between the fairy chimneys change from a minimum of 5.45 m for Zelve and 42.72 m for Kavak chimneys.
Fairy chimneys are developed in two stages. The first stage is the generation of topography suitable for the formation of fairy chimneys. Three main factors in this stage are degree of welding, thickness of ignimbrite and topographic slope. In the second stage, several local features contribute for the final shaping of the chimneys.
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Evaporate Mapping In Bala Region (ankara) By Remote Sensing TechniquesOztan, Nihat Serkan 01 June 2008 (has links) (PDF)
Evaporate minerals were very important raw materials in very different and broad
industries for years. Since gypsum became important raw material especially in
construction industry as plaster, demand to these minerals rises each following
year. The aim of this thesis is to map out these industrial raw materials by using
remote sensing techniques. Ankara Bala region has very rich Gypsum sites and
this region is showed as one of the best gypsum potential sites of Turkey according
to the studies of MTA so that this area is selected for the usage of remotely sensed
data.
For the remote sensing analyses ASTER images which have high spatial and
spectral resolution are used. The analyses are applied using PCI Geomatica
software and ARCGIS software is used for mapping purposes. Band ratio,
decorrelation stretch, principal component analysis and thermal indices are used in
order to map gypsum minerals. For gypsum minerals previously known Crosta
method is modified and by the selection of suitable bands and principle
components, gypsum minerals are tried to map and it is seen that it has a high
success. For TIR indices previously known Quartz index is modified as Sulfate
index and used for gypsum mapping. For relative accuracy all the results are add,
percentages of the results are estimated. According to results / 288 km2 area is
mapped as gypsum with the total of four methods but it is seen that only 8 km2 is
found by every methods. According to these percentages modified Crosta method
and Sulfate Index methods are showed the highest success.
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Morphological Analyses In Hattusha (bogazkale-turkey)Dundar, Pinar 01 August 2009 (has links) (PDF)
The purpose of this study is to investigate the morphological properties of the ancient city Hattusha and its surroundings. To achieve this, the analyses are conducted on the digital topographical maps at 1/25000 and 1/1000 scales.
Results of the analyses reveal that Hattusha is located over a north facing surface with slope values of 6 to 15 degrees within an elevation range of 1000 to 1250 m. All main building complexes are confined to a narrow slope interval of 2 to 15 degrees. Five regions are detected where the city wall deviates from the topographic divide resulting in a shorter path and addition of certain areas to the city. The volume of the city wall between Lion and King&rsquo / s gates is estimated to be 613966 m3 and covers an area of 130682 m2. Capacity of the eastern and southern ponds is estimated 15400 m3 and 22160 m3, respectively. Two potential dam sites are suggested outside the city with a total drainage basin of 0.2713 km2. For the visibility analysis performed inside the city, no
relation is found between the visibility and the elevation of points.
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Alteration Identification By Hyperspectral Remote Sensing In Sisorta Gold Prospect (sivas-turkey)Yetkin, Erdem 01 September 2009 (has links) (PDF)
Imaging spectrometry data or hyperspectral imagery acquired using airborne systems have been used in the geologic community since the early 1980&rsquo / s and represent a mature technology. The solar spectral range 0.4&ndash / 2.5 & / #956 / m provides abundant information about hydroxyl-bearing minerals, sulfates and carbonates common to many geologic units and hydrothermal alteration assemblages. Satellite based Hyperion image data is used to implement and test hyperspectral processing techniques to identify alteration minerals and associate the results with the geological setting. Sisorta gold prospect is characterized by porphyry related epithermal and mesothermal alteration zones that are mapped through field studies. Image specific corrections are applied to obtain error free image data. Extensive field mapping and spectroscopic survey are used to identify nine endmembers from the image. Partial unmixing techniques are applied and used to assess the endmembers. Finally the spectral correlation mapper is used to map the endmembers which are kaolinite, dickite, halloysite, illite, montmorillonite and alunite as clay group and hematite, goethite and jarosite as the iron oxide group. The clays and iron oxides are mapped with approximately eighty percent accuracy. The study introduces an image specific algorithm for alteration minerals identification and discusses the outcomes within the geological perspective.
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Geotechnical Characterization And Rock Mass Classification Of The Antalya Karstic Rock MassesSopaci, Evrim 01 October 2012 (has links) (PDF)
This thesis identifies the geotechnical parameters of the Antalya karstic foundation rocks
(travertine/tufa), which are highly variable in nature, by means of geological observations,
geotechnical site investigations, and field and laboratory geomechanics tests to examine
karstic (mainly tufa) rock mass behavior. Several geotechnical parameters such as
porosity, seismic wave velocity, uniaxial compressive strength, Young&rsquo / s modulus, tensile
strength, etc. that are thought to have significant influence on rock mass behavior have
been tested and statistically analyzed. Principal component analysis and multiple linear
and non-linear regression analyses have been carried out in order to reveal correlations
between the geotechnical parameters tested. Porosity has been statistically determined to
be one of the major parameters governing the strength of the Antalya tufa rock mass.
Intact rock failure criteria, among which Bieniawski&rsquo / s criterion has been proven to be
more appropriate for each tufa type (phytoherm framestone, phytoherm boundstone,
microcrystalline tufa, phytoclast tufa and intraclast tufa) along with the Antalya tufa rock
mass have been determined from the experiments. GSI rock mass classification of the
Antalya tufa rock mass, whose GSI value was recommended between 20± / 5 and 75± / 5, has
been attempted to be used in engineering design. Furthermore, the depth and dimension of
the karstic cavities and fractures have been investigated by the geophysical tests, surface
geological survey and subsurface investigations (borings and observation pits).
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Alteration Mapping By Remote Sensing: Application To Hasandag & / #8211 / Melendiz Volcanic ComplexYetkin, Erdem 01 September 2003 (has links) (PDF)
Certain alteration minerals are used to identify the hydrothermally altered rocks. Potassic, phyllic (sericitic), propylitic, argillic and silicification are main alteration types observed in volcanic rocks. The role of remote sensing in alteration mapping is the differentiation of the minerals that are unique for In this study, Landsat TM 5 images are used. General alteration trend in the area is mapped by conventional methods of color composite, band rationing, principal component analysis and multi-linear regression analysis. Detailed mineral mapping carried on by using the United States Geological Survey (USGS) spectral library data. Spectral reflectances of selected minerals are analyzed according to the TM band intervals and appropriate band ratios are selected. TM bands 1,2,3,4,5 and 7 are used. Outputs of mineral maps are investigated for zonal distribution. Mineral maps that are obtained by the mineral separation method reveal that the youngest volcanic complex Hasandag is poorly altered. Instead, Keç / iboyduran, Melendiz and Tepekö / y volcanic complexes are found to be highly altered with the pattern of clay dominant in the center and increasing oxidation towards flanks. Also the alteration along the previously mapped buried faults is a proof that the method can provide information about the alteration source.
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