Letteratura scientifica selezionata sul tema "Darai Limestone"

AbstractData-constrained modeling is a method that enables three-dimensional distribution of mineral phases and porosity in a sample to be modeled based on micro-computed tomography scans acquired at different X-ray energies. Here we describe an alternative method for measuring porosity, synchrotron K-edge subtraction using xenon gas as a contrast agent. Results from both methods applied to the same Darai limestone sample are compared. Reasonable agreement between the two methods and with other porosity measurements is obtained. The possibility of a combination of data-constrained modeling and K-edge subtraction methods for more accurate sample characterization is discussed.

Abstract. Permocalculus iagifuensis, a new species of gymnocodiacean alga is described from the Miocene of the Darai Limestone Formation of Papua New Guinea. The discovery of this species greatly extends the range of gymnocodiacean algae, which previously had only been confidently recorded from the Permian and Cretaceous. It also suggests an evolutionary link to the Recent genus Galaxaura (order Nemalionales; family Chaetangiaceae), which is the only extant alga bearing a similarity to the Gymnocodiaceae. Alternatively, a closer relationship to the green udoteacean algae (e.g. Halimeda) is considered. The microfauna and other microflora associated with this new species are briefly described.

Despite limited well control and paucity of seismic data, a regional study of the deepwater portion of the Gulf of Papua, Papua New Guinea (PNG), indicates a number of large structures at a variety of stratigraphic levels that are capable of holding significant volumes of hydrocarbons. The main structural elements east of the Fly River Platform the Pandora Ridge, Pandora Trough, Aure Trough, Port Moresby Trough and the northern portion of the Eastern Plateau were established during the Paleozoic and further enhanced by Late Cretaceous to Early Paleocene Coral Sea rifting in the southeast. Structuring in the region is mostly basement involved and extensional, and is overprinted by a later compressional pulse. Extensional and compressional regimes produce many potential traps. To date, exploration in the Gulf of Papua has been sporadic and mainly focussed in shallow water depths. The new reprocessed seismic data indicate the following Paleozoic to Recent plays, some of which contain multiple reservoir-seal pairs, sourced by non-marine and marine source rocks:extensional Paleozoic rift fault blocks;Upper Jurassic to Lower Cretaceous turbidites (Iagifu- Hedina-Toro sandstone equivalents);Campanian to Middle Paleocene Coral Sea synrift sandstone and basin floor fan equivalents (Pale/Barune Formations and equivalents);Middle Paleocene break-up unconformity fault blocks and intra-basinal highs;Upper Paleocene to Lower Eocene Pima Sandstone equivalent associated with the Middle Paleocene uplift and erosion;Oligocene to Lower Miocene lowstand deltas and turbidites;Miocene to Recent biohermal build-ups (possibly including a new limestone high, the Box Ridge, in front of the Pandora Ridge); Karstified Darai Limestone equivalent sealed by Aure Beds claystones;Miocene to Recent lowstand deltas and turbidites;Eocene to Pliocene stratigraphic onlaps flanking main structural highs; and,compressional plays associated with the Pliocene to Recent collision of the PNG and Pacific plates.

The Gobe Main and SE Gobe Fields were discovered in the early 1990s in the Papuan Fold Belt in the Highlands of Papua New Guinea. Heavily karstified Darai Limestone at the surface and heli-supported drilling made field appraisal problematic and expensive. With initial well spacing upwards of several kilometres, these fields were thought to be ‘tank’ type models, with field-wide extrapolations of gas-oil and oil-water contacts.The main Iagifu Sandstone reservoir in the Gobe fields comprises several fluvial and near-shore sand bodies, which are readily correlatable across the fields. The reservoir units display discrete coarsening upward sequences containing medium (~17%) porosity, medium to high permeability (>100 mD) sandstones. Although several different depositional facies are interpreted within the Iagifu reservoir, sand units are extensive on the scale of the Gobe structures and do not appear to be producing significant lateral boundaries or reservoir compartmentalisation.Geomechanical analysis has enabled the calculation of in-situ stress magnitudes and establishment of a geomechanical model for Gobe. Locally, the Gobe Main Field appears to be in a strike-slip stress regime (SHmax>Sv>Shmin). SHmax directions vary from NNE– SSW to NE–SW. Stress magnitudes indicate the structure is near frictional equilibrium, with a high proportion of natural fractures and faults critically stressed for shear failure. Since first oil in early 1998, performance results have indicted pressure segregation of many of the wells in both the Gobe Main and SE Gobe fields. Although only one fault has been positively identified at the reservoir level, the mapped faults appear to have sand-on-sand juxtaposition with minimal (

Hypertension is a disease that often lead to patient death as it does not have specific symptoms. The high prevalence in Bogor Regency caused by minimal health facilities, so there was no guarantee of occupational health for workers and the workers lack of knowledge. Objective: To determine the risk factors that affected systolic blood pressure in limestone miners in Klapanunggal. Method: Uses observational analytic study with cross sectional design with a total of 47 people. Result: The measurement of noise intensity are 83.2 dB on a breaker and 91.7 dB on a stone crusher. The average systolic blood pressure before and after work was 110.28 mmHg and 126.23 mmHg. The results of one-way ANOVA test, a correlation between noise intensity, working period, prolonged exposure, and smoking habits with systolic blood pressure with p=0.001 was obtained. According to dummy regression test, noise intensity were the most influential. Workers exposed to noise with an intensity normal had an average increase 10.45 mmHg, while those exposed to an intensity abnormal 22.27 mmHg. Conclusion: Noise intensity, working period, prolonged exposure, and smoking habits affect systolic blood pressure and the most influential factor was noise intensity.

AbstractThe Yangtze Platform preserves relatively thick carbonate successions and excellent fossil records across the Ediacaran–Cambrian boundary interval. The intensely studied Meishucun section in East Yunnan was one of the Global Stratotype Section candidates for the Precambrian–Cambrian boundary. However, depositional breaks were suspected in the section and the first appearance of small shelly fossils could not be verified. The Laolin section located in NE Yunnan is more continuous and shows great potential for global correlation of carbon isotope features across the Precambrian–Cambrian boundary. However, the stratigraphic framework and correlations were controversial. We studied and systematically sampled the Laolin section and present here new carbon isotope data for this section. The Laolin section consists of, in ascending order, the Baiyanshao dolostone of the Dengying Formation, the Daibu siliceous dolostone, Zhongyicun dolomitic phosphorite, lower Dahai dolostone and upper Dahai limestone of the Zhujiaqing Formation, and the black siltstone of the Shiyantou Formation. Our data reveal a large negative δ13C excursion (−7.2‰, L1′) in the Daibu Member, which matches the previously published data for the Laolin section, and a large positive excursion (+3.5‰, L4) in the Dahai Member, which was not shown in the published data. The excursion L1′ correlates well with the similarly large negative excursion near the first appearance of small shelly fossils in Siberia and Mongolia. Similar magnitude excursions are also known from Morocco and Oman, for which there are no robust fossil constraints but from where volcanic ash beds have been dated precisely at 542 Ma, thus confirming a global biogeochemical event near the Ediacaran–Cambrian boundary. Our data also indicate that deposition was more continuous at the Laolin section compared with the Meishucun section, where there are no records of a comparable negative excursion near the Ediacaran–Cambrian boundary, nor any comparable positive excursion in the Dahai Member. Therefore, the Laolin section has proven potential to be a supplementary Global Stratotype Section for the Ediacaran–Cambrian boundary on the Yangtze Platform.

Penyu memiliki kebiasaan unik dalam siklus reproduksi yakni bertelur di lokasi di mana mereka ditetaskan, sekalipun wilayah pantai terus mengalami perubahan. Untuk itu, dipandang perlu melakukan inventarisasi dan menyediakan deskripsi keadaan lingkungan tempat bertelur penyu. Pantai Taturian Desa Batumbalango merupakan salah satu dari enambelas tempat bertelur di pulau Karakelang Talaud. Tujuan penelitian ini untuk menyediakan dideskripsi lokasi bertelur penyu di pantai Taturian mencakup posisi geografis, panjang-lebar pantai, kemiringan pantai, komposisi sedimen sekitar lubang sangkar peletakkan telur dan vegetasi darat. Posisi geografis ditentukan dengan menggunakan GPS, sedimen dianalisis menurut skala AFNOR, vegerasi difoto. Data disajikan secara deskriptif. Hasil menunjukkan bahwa pantai Taturian terletak pada 04º23’47,5” LU dan 126º41’37,1” BT berfungsi pula sebagai tempat penambatan perahu nelayan; panjang pantai ±100m dibatasi tanjung berbatu limestone, lebar pantai 19-20m, sedimen yang dominan adalah pasir sedang (44%); kemiringan pantai 4,5-9,0% atau termasuk kriteria landai hingga lereng miring. Lokasi ini berbatasan dengan pemukiman dan perkebunan kelapa. Mengingat penyu dinyatakan sebagai zatwa lindung, sepatutnya pantai Taturian ditetapkan sebagai lokasi konservasi penyu

A sequence stratigraphic study was conducted on the Mendi and Darai Limestone Megasequences in the foreland area of the Papuan Basin in Papuan New Guinea. It involved the integrated use of seismic, wireline log, well core and cuttings, strontium isotope age and biostratigraphic data. This study enhanced the understanding of the structure, stratigraphy and depositional architecture of the limestones, and the morphology of the basin at the time of deposition. The results of the study were integrated with published geological and tectonic models for the Papuan Basin to develop a consistent and coherent model for the depositional history of the limestones. Eleven third-order sequences were delineated within the Mendi and Darai Limestone Megasequences. Eight depositional facies were interpreted across these sequences, namely deep-shelf, shallow-shelf, backreef, reef, shoal, forereef, basin margin and submarine fan facies. Each facies was differentiated according to seismic character and geometry, well core and cuttings descriptions, and its position in the depositional framework of the sequence. Deposition of the Mendi Limestone Megasequence commenced in the Eocene in response to thermal subsidence and eustatic sea-level rise. Sedimentation comprised open-marine, shallow-water, shelfal carbonates. During the middle of the Oligocene, the carbonate shelf was exposed and eroded in response to the collision of the Australian and Pacific Plates, or a major global eustatic sea-level fall. Sedimentation recommenced in the Late Oligocene, however, in response to renewed extensional faulting and subsidence associated with back-arc extension. This marked the onset of deposition of the Darai Limestone Megasequence in the study area. The KFZ, OFZ and Darai Fault were reactivated during this time, resulting in the oblique opening of the Omati Trough. Sedimentation was initially restricted to the Omati Trough and comprised deep and shallow-marine shelfal carbonates. By the Early Miocene, however, movement on the faults had ceased and an extensive carbonate platform had developed across the Gulf of Papua. Carbonate reef growth commenced along topographic highs associated with the KFZ, and led to the establishment of a rimmed carbonate shelf margin. Shallow to locally deeper-marine, shelfal carbonates were deposited on this shelf, and forereef, submarine fan and basin margin carbonates were deposited basinward of the shelf margin. The Uramu High and parts of the Pasca High became submerged during this time and provided sites for pinnacle reef development. During the middle of the Early Miocene, a major global eustatic sea-level fall or flexure of the Papuan Basin associated with Early Miocene ophiolite obduction subaerially exposed the carbonate shelf. This resulted in submarine erosion of the forereef and basin margin sediments. Towards the end of the Early Miocene, however, sedimentation recommenced. Shallow-marine, undifferentiated wackestones and packstones were deposited on the shelf; forereef, submarine fan and basin margin sediments were deposited basinward of the shelf margin; and reef growth recommenced along the shelf margin and on the Pasca and Uramu Highs. By the end of the Early Miocene, however, the pinnacle reef on the Pasca High had drowned. During the middle of the Middle Miocene, subtle inversion associated with ophiolite obduction subaerially exposed the carbonate shelf, and resulted in submarine erosion of the forereef and basin margin sediments. Sedimentation recommenced towards the end of the Middle Miocene, however, in response to eustatic sea-level rise and flexure of the crust associated with foreland basin development. Shallow marine, undifferentiated wackestones, packstones and grainstones were deposited on the shelf; carbonate shoals were deposited along the shelf margin; and forereef, submarine fan and basin margin carbonates were deposited basinward of the shelf margin. Carbonate production rapidly outpaced accommodation space on the shelf during this time, resulting in highstand shedding and the development of a large prograding submarine fan complex basinward of the shelf margin. By the Late Miocene, carbonate deposition had ceased across the majority of the study area in response to a major global eustatic sea-level fall or inversion associated with terrain accreation events along the northern Papuan margin. Minor carbonate deposition continued on parts of the Uramu High, however, until the middle of the Late Miocene. During the latest Miocene, clastic sediments prograded across the carbonate shelf, infilling parts of the foreland basin. Plio-Pleistocene compression resulted in inversion and erosion of the sedimentary package in the northwestern part of the study area. In the southeastern part of the Papuan Basin, however, clastic sedimentation continued to the present day.