Structural complexity at and around the Triassic-Jurassic GSSP at Kuhjoch, Northern Calcareous Alps, Austria

One of the key requirements for a Global Stratotype Section and Point (GSSP) is the absence of tectonic disturbance. The GSSP for the Triassic–Jurassic system boundary was recently defined at Kuhjoch, Northern Calcareous Alps, Austria. New field observations in the area of the Triassic–Jurassic boundary GSSP site demonstrate that the overturned, tight, and almost upright Karwendel syncline was formed at semibrittle deformation conditions, confirmed by axial planar foliation. Tight to isoclinal folds at various scales were related to a tectonic transport to the north. Brittle faulting occurred before and after folding as confirmed by tilt tests (the rotation of structural data by the average bedding). Foliation is ubiquitous in the incompetent units, including the Kendlbach Formation at the GSSP. A reverse fault (inferred to be formed as a normal fault before folding) crosscuts the GSSP sections, results in the partial tectonic omission of the Schattwald Beds, and thus makes it impossible to measure a complete and continuous stratigraphic section across the whole Kendlbach Formation. Based on these observations, the Kuhjoch sections do not fulfil the specific requirement for a GSSP regarding the absence of tectonic disturbances near boundary level

Spatially resolved Spectro-photometry of M81: Age, Metallicity and Reddening Maps

In this paper, we present a multi-color photometric study of the nearby spiral galaxy M81, using images obtained with the Beijing Astronomical Observatory 60/90 cm Schmidt Telescope in 13 intermediate-band filters from 3800 to 10000{\AA}. The observations cover the whole area of M81 with a total integration of 51 hours from February 1995 to February 1997. This provides a multi-color map of M81 in pixels of 1\arcsec.7 \times 1\arcsec.7. Using theoretical stellar population synthesis models, we demonstrate that some BATC colors and color indices can be used to disentangle the age and metallicity effect. We compare in detail the observed properties of M81 with the predictions from population synthesis models and quantify the relative chemical abundance, age and reddening distributions for different components of M81. We find that the metallicity of M81 is about $Z=0.03$ with no significant difference over the whole galaxy. In contrast, an age gradient is found between stellar populations of the central regions and of the bulge and disk regions of M81: the stellar population in its central regions is older than 8 Gyr while the disk stars are considerably younger, $\sim 2$ Gyr. We also give the reddening distribution in M81. Some dust lanes are found in the galaxy bulge region and the reddening in the outer disk is higher than that in the central regions.Comment: Accepted for publication in AJ (May 2000 issue). 27 pages including 6 figures. Uses AASTeX aasms4 styl

Spectral Energy Distributions and Age Estimates of 78 Star Clusters in M33

In this third paper of our series, we present CCD spectrophotometry of 78 star clusters that were detected by Chandar, Bianchi, & Ford in the nearby spiral galaxy M33. CCD images of M33 were obtained as a part of the BATC Color Survey of the sky in 13 intermediate-band filters from 3800 to 10000{\AA}. By aperture photometry, we obtain the spectral energy distributions of these 78 star clusters. As Chandar, Bianchi, & Ford did, we estimate the ages of our sample clusters by comparing the photometry of each object with theoretical stellar population synthesis models for different values of metallicity. We find that the sample clusters formed continuously in M33 from $\sim 3\times10^6$ -- $10^{10}$ years. This conclusion is consistent with Chandar, Bianchi, & Ford. The results also show that, there are two peaks in cluster formation, at $\sim 8\times10^6$ and $\sim 10^9$ years in these clusters.Comment: 29 pages, one figure is gif form, will appear in the June 2002 issue of A

Magnetostratigraphy of the Lower Triassic beds from Chaohu(China) and its implications for the Induan–Olenekian stage boundary.

A magnetostratigraphic study was performed on the lower 44 m of the West Pingdingshan section near Chaohu city, (Anhui province, China) in order to provide a magnetic polarity scale for the early Triassic. Data from 295 paleomagnetic samples is integrated with a detailed biostratigraphy and lithostratigraphy. The tilt-corrected mean direction from the West Pingdingshan section, passes the reversal and fold tests. The overall mean direction after tilt correction is D=299.9º, I=18.3º (κ=305.2, α95=1.9, N=19). The inferred paleolatitude of the sampling sites (31.6ºN, 117.8ºE) is about 9.4º, consistent with the stable South China block (SCB), though the declinations indicate some 101o counter-clockwise rotations with respect to the stable SCB since the Early Triassic. Low-field anisotropy of magnetic susceptibility indicates evidence of weak strain. The lower part of the Yinkeng Formation is dominated by reversed polarity, with four normal polarity magnetozones (WP2n to WP5n), with evidence of some thinner (<0.5 m thick) normal magnetozones. The continuous magnetostratigraphy from the Yinkeng Formation, provides additional high-resolution details of the polarity pattern through the later parts of the Induan into the lowest Olenekian. The magnetostratigraphic and biostratigraphic data shows the conodont marker for the base of the Olenekian (first presence of Neospathodus waageni) is shortly prior to the base of normal magnetozone WP5n. This provides a secondary marker for mapping the base of the Olenekian into successions without conodonts. This section provides the only well-integrated study from a Tethyan section across this boundary, but problems remain in definitively relating this boundary into Boreal sections with magnetostratigraphy

Biostratigraphy of the Danian/Selandian transition: A case study from Kamestan anticline section, northwest of Izeh city in Khuzestan province, Southern Iran

The planktonic foraminifera turnover across the Danian-Selandian boundary (early to late Paleocene, ~60 Ma) has been studied in the Kamestan anticline section. The studied interval span planktonic foraminifera zones P2-P3. In this section Danian-Selandian boundary is located in Pabedeh &#x2013; Gurpi Formations transition. Here, the boundary of Pabeh and Gurpi Formations is a transitional one and identified by with color change of from grey shale to purple shale of Gurpi Formation to Pabdeh Formation .&#xd;&#xa;&#xd;&#xa

Exploiting surroundedness for saliency detection: a boolean map approach

We demonstrate the usefulness of surroundedness for eye fixation prediction by proposing a Boolean Map based Saliency model (BMS). In our formulation, an image is characterized by a set of binary images, which are generated by randomly thresholding the image's feature maps in a whitened feature space. Based on a Gestalt principle of figure-ground segregation, BMS computes a saliency map by discovering surrounded regions via topological analysis of Boolean maps. Furthermore, we draw a connection between BMS and the Minimum Barrier Distance to provide insight into why and how BMS can properly captures the surroundedness cue via Boolean maps. The strength of BMS is verified by its simplicity, efficiency and superior performance compared with 10 state-of-the-art methods on seven eye tracking benchmark datasets.US National Science Foundation; 1059218; 1029430http://cs-people.bu.edu/jmzhang/BMS/BMS_iccv13_preprint.pdfAccepted manuscrip

Grid Search in Stellar Parameters: a software for spectrum analysis of single stars and binary systems

The currently operating space missions, as well as those that will be launched in the near future, (will) deliver high-quality data for millions of stellar objects. Since the majority of stellar astrophysical applications still (at least partly) rely on spectroscopic data, an efficient tool for the analysis of medium- to high-resolution spectroscopy is needed. We aim at developing an efficient software package for the analysis of medium- to high-resolution spectroscopy of single stars and those in binary systems. The major requirements are that the code has a high performance, represents the state-of-the-art analysis tool, and provides accurate determinations of atmospheric parameters and chemical compositions for different types of stars. We use the method of atmosphere models and spectrum synthesis, which is one of the most commonly used approaches for the analysis of stellar spectra. Our Grid Search in Stellar Parameters (GSSP) code makes use of the OpenMPI implementation, which makes it possible to run in parallel mode. The method is first tested on the simulated data and is then applied to the spectra of real stellar objects. The majority of test runs on the simulated data were successful in the sense that we could recover the initially assumed sets of atmospheric parameters. We experimentally find the limits in signal-to-noise ratios of the input spectra, below which the final set of parameters gets significantly affected by the noise. Application of the GSSP package to the spectra of three Kepler stars, KIC11285625, KIC6352430, and KIC4931738, was also largely successful. We found an overall agreement of the final sets of the fundamental parameters with the original studies. For KIC6352430, we found that dependence of the light dilution factor on wavelength cannot be ignored, as it has significant impact on the determination of the atmospheric parameters of this binary system.Comment: 19 pages, 6 figures, 4 tables, 2 appendices one of which includes detailed description of input and output files. Accepted for publication in Astronomy & Astrophysi