Intrusion versus inversion—a 3D density model of the southern rim of the Northwest German Basin     

Filiz Bilgili  Hans-Jürgen Götze  Roman Pašteka  Sabine Schmidt  Ron Hackney 《International Journal of Earth Sciences》2009,98(3):571-583

An unsolved problem of regional importance for both the evolution and structure of the Northwest German Basin is the existence or non-existence of the so-called Bramsche Massif. Explaining the nature of this massif and the cause of a related strong, positive Bouguer anomaly (Bramsche Anomaly) is critical. In the study described here, we tested an existing “intrusion model” against a newer “inversion model” in the southern Northwest German Basin. In the intrusion model, the strongly-positive Bouguer anomaly represents the gravity effect of an intrusion at depths between 6 and 10 km. More recent interpretations invoke tectonic inversion rather than intrusion to explain increased burial and the low level of hydrocarbon maturity found in boreholes. We tested these different interpretations by constructing 3D forward density models to 15 km depth. The intrusion model was updated and adjusted to incorporate recent data and we also modelled pre-Zechstein structures using different scenarios. The final model has a very good fit between measured and modelled gravity fields. Based on currently available seismic and structural models, as well as borehole density measurements, we show that the positive Bouguer anomaly cannot be modeled without a high-density, intrusive-like body at depth. However, further in-sight into the crustal structures of the Bramsche region requires more detailed investigations. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.  相似文献   

Hydrocarbon generation potential of the uppermost Jurassic—basal Cretaceous Sulaiy formation, South Iraq     

Thamer Khazaal Al-Ameri  Furat Ata’a Al-Musawi 《Arabian Journal of Geosciences》2011,4(1-2):53-58

Organic geochemical analysis, palynology, and PetroMod software for the organic matters of subsurface Tithonian to Valanginian Sulaiy formation of six wells in Basrah Region, South Iraq showed evidences for hydrocarbon generation potential. These analyses include quantitative studies such as pyrolysis, fluorescence spectroscopy, and total organic carbon (TOC), while the qualitative studies are the textural microscopy used in evaluating amorphous organic matter for palynofacies analysis leading to hydrocarbon assessments. High TOC content of up to 7.3 wt.%, kerogen type II of mesoliptinic type with hydrogen index of up to 466 mg HC/g TOC, and mature organic matter along with dysoxic–anoxic environment and stratigraphic framework have rated the succession as a source rock for oil with ordinate gas, not only in Iraq but also in neighboring Kuwait and Saudi Arabia. This case study is also inferred for hydrocarbon generation and expulsion by PetroMod software which confirmed the source potential.  相似文献   

Tracing the formation history of intermediate-age star clusters in the Small Magellanic Cloud     

Andrés E. Piatti  Ata Sarajedini  Doug Geisler  Juan Seguel  David Clark 《Monthly notices of the Royal Astronomical Society》2005,358(4):1215-1230

Colour–magnitude diagrams (CMDs) are presented for the first time for 10 star clusters projected on to the Small Magellanic Cloud (SMC). The photometry was carried out in the Washington system C and T ₁ filters allowing the determination of ages by means of the magnitude difference between the red giant clump and the main-sequence turnoff (MSTO), and metallicities from the red giant branch (RGB) locus. The clusters all have ages in the range 1.5–4 Gyr and metallicities between  −1.3 < [Fe/H] < −0.6  , with respective errors of ∼0.5 Gyr and 0.3 dex. This increases substantially the sample of intermediate-age clusters in the SMC with well-derived parameters. We combine our results with those for other clusters in the literature to derive as large and homogeneous a data base as possible (totalling 26 clusters) in order to study global effects. We find evidence for two peaks in the age distribution of SMC clusters, at ∼6.5 and 2.5 Gyr, in good agreement with previous hints involving smaller samples. The most recent peak occurs at a time that corresponds to a very close encounter between the Large Magellanic Cloud (LMC) and the SMC according to the recent dynamical models of Bekki et al. that they used to explain the enhancement of LMC clusters with this age. It appears cluster formation may have been similarly stimulated in the SMC by this encounter as well. We also find very good agreement between cluster ages and metallicities and the prediction from a bursting model from Pagel and Tautvaišienė with a burst that occurred 3 Gyr ago. These two lines of evidence together favour a bursting cluster formation history as opposed to a continuous one for the SMC.  相似文献   

North-South asymmetry in the solar flare index     

Tamer Ataç  Atila Özgüç 《Solar physics》1996,166(1):201-208

This paper reports the results of a study of the N-S asymmetry in the flare index using the results of Knoka (1985) combined with our results for the solar cycles 17 to the current cycle 22. By comparing the time-variation of the asymmetry curve with the solar activity variation of the 11-year cycle, we have found that the flare index asymmetry curve is not in phase with the solar cycle and that the asymmetry peaks during solar minimum. A periodic behaviour in the N-S asymmetry appears: the activity in one hemisphere is more important during the ascending part of the cycle whereas during the descending part the activity becomes more important in the other hemisphere. The dominance of flare activity in the southern hemisphere continues during cycle 22 and, according to our findings, this dominance will increase gradually during the following cycle 23.  相似文献   

Contamination,toxicity and risk assessment of heavy metals and metalloids in sediments of Shahid Rajaie Dam,Sefidrood and Shirinrood Rivers,Iran     

Ata Shakeri  Rahimeh Shakeri  Behzad Mehrabi 《Environmental Earth Sciences》2016,75(8):679

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Mapping groundwater potential field using catastrophe fuzzy membership functions and Jenks optimization method: a case study of Maragheh-Bonab plain,Iran     

Sina Sadeghfam  Yousef Hassanzadeh  Ata Allah Nadiri  Rahman Khatibi 《Environmental Earth Sciences》2016,75(7):545

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Assessing the influence of climate change characteristics on the rainfall duration of Turkey     

Nihal Ata Tutkun  Gamze Özel 《Natural Hazards》2016,84(3):2265-2277

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Young stellar populations in early-type galaxies in the Sloan Digital Sky Survey     

Louisa A. Nolan  Somak Raychaudhury  Ata Kabán 《Monthly notices of the Royal Astronomical Society》2007,375(1):381-387

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Evaluation of the short-term periodicities in the flare index between the years 1966–2002     

Atila Özgüç  Tamer Ataç  Ján Rybák 《Solar physics》2004,223(1):287-304

The short-term periodicities of the flare index are investigated in detail using Fourier and wavelet transforms for the full disc and for the northern and the southern hemispheres of the Sun separately over the epoch of almost 4 cycles (1966–2002). The most pronounced power peaks were found by the Fourier transform to be present at 25.6, 27.0, 30.2, and 33.8 days. The wavelet transform results show that the occurrence of periodicities of flare index power is highly intermittent in time. A comparison of the results of the Fourier transform and the time-period wavelet transform of the flare index time series has clarified the importance of different periodicities, whether they are or are not the harmonics of the basic ones, as well as the temporal location of their occurrence. We found that the modulation of the flare index due to the 27-day solar rotation is more pronounced during the declining portion of solar cycle than during the rising portion.  相似文献   

Flare Index of Solar Cycle 22     

Ataç  Tamar  Özgüç  Atila 《Solar physics》1998,180(1-2):397-407

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