Local zonation of foraminifera in the North West Java Basin

Abstrac
Role of analysis foraminifera in North West Java Basin is importance because it can be determine age and depositional environment very well. This research observes foraminifers’ that emerging at the age Miocene in North West Java Basin. Research data is result of biostratigraphic analysis from 6 chosen well representing some fields oil and gas property of XXXXX which ahead done by group of Stratigraphy PPPTMGB "LEMIGAS" through service. The purpose is analyze and makes local of zonation foraminiferal that later earns as reference at the time of determination of zonation or age other well in North West Java Basin.

The age Miocene of planktonic foraminifers is enough abundance especially in the Upper Cibulakan and Parigi Formation, but unable to grow in the Talangakar and Baturaja Formation. The growth of bentonic foraminifers is good enough started from Talang Akar until Parigi Formation. Based on some literature and calibrated with nannoplankton and palinomorf, the benthonic foraminiferal earn also determine age. This thing based from first or last appearance of larger and smaller benthonic foraminiferal. The marker species of planktonic foraminifers are composed of Globorotalia tumida, Globorotalia merotumida, Globorotalia plesiotumida, Globorotalia acostansis, Globorotalia siakensis, Orbulina universa, Globigerinoides subquadratus, Globorotalia fohsi robusta, Globorotalia fohsi fohsi, Globigerinoides bisphaericus and Globigerinoides diminutus. The larger benthonic foraminiferal species is Lepidocyclina (T) orientalis, Borelis melo, Lepidocyclina (N) inflata, Lepidocyclina (N) tournoueri, Spiroclypeus sp. and Miogypsina sp. The age diagnostic species of the benthonic foraminifera of rotaliid group covers Pseudorotalia catiliformis, Pseudorotalia indopacifica, Pseudorotalia shcroeteriana angusta, Cavarotalia annecten, Asterorotalia yabei and Ammonia umbonata.

Result of this research is the form of 3 column of local zonation foraminiferal Miocene covering planktonic foraminiferal, larger benthonic foraminiferal and smaller benthonic foraminiferal (rotaliid group) zonation. Benthonic foraminiferal zonation only as complement when marker species of planktonic foraminifers unable to grow.

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Geochronology

From Wikipedia, the free encyclopedia

In the natural sciences under the umbrella of natural history, Geochronology is the science of determining the absolute age of rocks, fossils, and sediments, within a certain degree of uncertainty inherent within the method used. A variety of dating methods are used by geologists to achieve this.

Geochronology is different in application from biostratigraphy, which is the science of assigning sedimentary rocks to a known geological period via describing, cataloguing and comparing fossil floral and faunal assemblages. Biostratigraphy does not directly provide an absolute age determination of a rock, merely places it within an interval of time at which that fossil assemblage is known to have coexisted. Both disciplines work together hand in hand however, to the point they share the same system of naming rock layers and the time spans utilized to classify layers within a strata. (See table at right for terminology.)

For instance, with reference to the Geologic time scale, the Upper Permian (Lopingian) lasted from 270.6 +/- 0.7 Ma (Ma = millions of years ago) until somewhere between 250.1 +/- 0.4 Ma (oldest known Triassic) and 260.4 +/- 0.7 Ma (youngest known Lopingian) - a gap in known, dated fossil assemblages of nearly 10 Ma. While the biostratigraphic age of an Upper Permian bed may be shown to be Lopingian, the true date of the bed could be anywhere from 270 to 251 Ma.

On the other hand, a granite which is dated at 259.5 +/- 0.5 Ma can reasonably safely be called "Permian", or most properly, to have intruded in the Permian.
The science of geochronology is the prime tool used in the discipline of chronostratigraphy, which attempts to derive absolute age dates for all fossil assemblages and determine the geologic history of the Earth and extraterrestrial bodies.

Dating methods
• Radiometric techniques measure the decay of radioactive isotopes, and other radiogenic activity.
• Incremental techniques measure the regular addition of material to sediments or organisms.
• Correlation of marker horizons allow age-equivalence to be established between different sites.

Radiometric dating
By measuring the amount of radiocative decay of a radioactive isotope with a known half-life, geologists can establish the absolute age of the parent material. A number of radioactive isotopes are used for this purpose, and depending on the rate of decay, are used for dating different geological periods.
• Radiocarbon dating. This technique measures the decay of Carbon-14 in organic material (e.g. plant macrofossils), and can be applied to samples younger than about 50,000 years.
• Uranium-lead dating. This technique measures the ratio of two lead isotopes (Pb-206 and Pb-207) to the amount of uranium in a mineral or rock. Often applied to the trace mineral zircon in igneous rocks, this method is one of the two most commonly used (along with argon-argon dating) for geologic dating. Uranium-lead dating is applied to samples older than about 1 million years.
• Uranium-thorium dating. This technique is used to date speleothems, corals, carbonates, and fossil bones. Its range is from a few years to about 700,000 years.
• Potassium-argon dating and argon-argon dating. These techniques date metamorphic, igneous and volcanic rocks. They are also used to date volcanic ash layers within or overlying paleoanthropologic sites. The younger limit of the argon-argon method is a few thousand years.

Other radiogenic dating techniques include:
• Fission track dating
• Cosmogenic isotope dating
• Rubidium-strontium dating
• Samarium-neodymium dating
• Rhenium-osmium dating
• Lutetium-hafnium dating
• Paleomagnetic dating
• Thermo-luminescence dating (quartz exposure to heat)

Luminescence dating
Luminescence dating techniques observe 'light' emitted from materials such as quartz, diamond, feldspar, and calcite. Many types of luminescence techniques are utilized in geology, including optically stimulated luminescence (OSL), cathodoluminescence (CL), and thermoluminescence (TL). Thermoluminescence and optically stimulated luminescence are used in archaeology to date 'fired' objects such as pottery or cooking stones, and can be used to observe sand migration.

Incremental dating
Incremental dating techniques allow the construction of year-by-year annual chronologies, which can be fixed (i.e. linked to the present day and thus calendar or sidereal time) or floating.
• Dendrochronology
• Ice cores
• Lichenometry
• Varves

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Environmental Geology

From Wikipedia, the free encyclopedia

Environmental geology, like hydrogeology, is a multidisciplinary field of applied science and is closely related to engineering geology and somewhat related to environmental geography. They all involve the study of the interaction of humans with the geologic environment including the biosphere, the lithosphere, the hydrosphere, and to some extent the atmosphere,. It includes:
• managing geological and hydrogeological resources such as fossil fuels, minerals, water (surface and ground water), and land use.
• defining and mitigating exposure of natural hazards on humans
• managing industrial and domestic waste disposal and minimizing or eliminating effects of pollution, and
• performing associated activities, often involving litigation

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Enginering Geology

From Wikipedia, the free encyclopedia

Engineering Geology is the application of the geologic sciences to engineering practice for the purpose of assuring that the geologic factors affecting the location, design, construction, operation and maintenance of engineering works are recognized and adequately provided for. Engineering geologists investigate and provide geologic and geotechnical recommendations, analysis, and design. Engineering geologic studies may be performed during the planning, environmental impact analysis, civil engineering design, value engineering and construction phases of public and private works projects, and during post-construction and forensic phases of projects. Works completed by engineering geologists include; geologic hazards, geotechnical, material properties, landslide and slope stability, erosion, flooding, dewatering, and seismic investigations, etc. Engineering geologic studies are performed by a geologist or engineering geologist educated, professionally trained and skilled at the recognition and analysis of geologic hazards and adverse geologic conditions. Their overall objective is the protection of life and property against damage and the solution of geologic problems.

Engineering geologic studies may be performed:
• for residential, commercial and industrial developments;
• for governmental and military installations;
• for public works such as a power plant, wind turbine, transmission line, sewage treatment plant, water treatment plant, pipeline (aqueduct, sewer, outfall), tunnel, trenchless construction, canal, dam, reservoir, building, railroad, transit, highway, bridge, seismic retrofit, airport and park;
• for mine and quarry excavations, mine tailing dam, mine reclamation and mine tunneling;
• for wetland and habitat restoration programs;
• for coastal engineering, sand replenishment, bluff or sea cliff stability, harbor, pier and waterfront development;
• for offshore outfall, drilling platform and sub-sea pipeline, sub-sea cable; and
• for other types of facilities.
Geohazards and adverse geo-conditions
Typical geohazards or other adverse conditions evaluated by an engineering geologist include:
• fault rupture on seismically active faults ;
• seismic and earthquake hazards (ground shaking, liquefaction, lurching,lateral spreading, tsunami and seiche events);
• landslide, mudflow, rock fall and avalanche hazards ;
• unstable slopes and slope stability;
• erosion;
• slaking and heave of geologic formations;
• ground subsidence (such as due to ground water withdrawal, sinkhole collapse, cave collapse, decomposition of organic soils, and tectonic movement);
• volcanic hazards (volcanic eruptions, hot springs, pyroclastic flows, debris flows, debris avalanche, gas emissions, volcanic earthquakes);
• non-rippable or marginally rippable rock requiring heavy ripping or blasting;
• weak and collapsible soils;
• shallow ground water/seepage; and
• other types of geologic constraints.
An engineering geologist or geophysicist may be called upon to evaluate the excavatability (i.e. rippability) of earth (rock) materials to assess the need for pre-blasting during earthwork construction, as well as associated impacts due to vibration during blasting on projects.

Methods and reporting
The methods used by engineering geologists in their studies include
• geologic field mapping of geologic structures, geologic formations, soil units and hazards;
• the review of geologic literature, geologic maps, geotechnical reports, engineering plans, environmental reports, stereoscopic aerial photographs, remote sensing data, Global Positioning System (GPS) data, topographic maps and satellite imagery;
• the excavation, sampling and logging of earth/rock materials in drilled borings, backhoe test pits and trenches, fault trenching, and bulldozer pits;
• geophysical surveys (such as seismic refraction traverses, resistivity surveys, ground penetrating radar (GPR) surveys, magnetometer surveys, electromagnetic surveys, high-resolution sub-bottom profiling, and other geophysical methods);
• deformation monitoring as the systematic measurement and tracking of the alteration in the shape or dimensions of an object as a result of the application of stress to it manually or with an automatic deformation monitoring system; and
• other methods.

The field work is typically culminated in analysis of the data and the preparation of an engineering geologic report, geotechnical report, fault hazard or seismic hazard report, geophysical report, ground water resource report or hydrogeologic report. The engineering geologic report is often prepared in conjunction with a geotechnical report, but commonly provide geotechnical analysis and design recommendations independent of a geotechnical report. An engineering geologic report describes the objectives, methodology, references cited, tests performed, findings and recommendations for development. Engineering geologists also provide geologic data on topograpic maps, aerial photographs, geologic maps, Geographic Information System (GIS) maps, or other map bases.

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