Biostratigraphy and depositional facies of the Cretaceous-Tertiary boundary strata in Amakusa-Shimojima,Kyushu, Western Japan

The Upper Himenoura Subgroup exposed in the island of Amakusa-Shimojima, Kyushu, Japan shows an example of the terminal Cretaceous stratigraphic record in the circum Pacific region. This sequence is a part of the Upper Cretaceous intra-arc basins of southwest Japan. Four cycles of upward coarse-graded facies are recognized. Each cycle consists of a basinal mud facies in the lower part and a tide-dominated shallow marine to brackish coarse clastic facies in the upper part. Biostratigraphic correlation chiefly based on ammonites, inocerami and trigoniids indicates that this sequence is Campanian to Maastrichtian in age. The occurrence of the above three fossils decreases upward and is terminated at the top of the sequence, being replaced by a molluscan assemblage similar to the Danian. This suggests that the sedimentation may have continued to the very end of the Cretaceous period and possibly to the beginning of the Tertiary.     

Gravity anomaly modeling of sedimentary basins by means of multiple structures and exponential density contrast-depth variations: A space domain approach

An automatic modeling scheme is developed in the space domain to interpret the gravity anomalies of sedimentary basins, among which the density contrast decreases exponentially with depth. Forward modeling is realized in the space domain using a combination of both analytical and numerical approaches. A collage of vertical prisms having equal widths, whose depths are to be estimated, describes the geometry of a sedimentary basin. Initial depths of a sedimentary basin are predicted using the Bouguer slab formula and subsequently updated, iteratively, based on the differences between the observed and theoretical gravity anomalies until the modeled gravity anomalies mimic the observed ones. The validity and applicability of the method is demonstrated with a synthetic and two real field gravity anomalies, one each over the Chintalpudi sub-basin in India and the other over the San Jacinto graben, California. In case of synthetic example, the assumed structure resembles a typical intracratonic rift basin formed by normal block faulting and filled with thick section of sediments. The proposed modeling technique yielded information that is consistent with the assumed parameters in the case of synthetic structure and with the available/drilling depths in case of field examples.     

1979年印度夏季风活跃、中断和撤退时期欧亚上空风场和温度场的变化

本文对1979年夏季印度西南季风活跃、中断和撤退时欧亚地区大范围环流和温度场进行了分析。结果表明,该年季风活动的变率与欧亚中高纬环流形势的演变有明显关系。季风活跃期,高空西风带显著北移,西藏高原上空有高空反气旋环流建立、发展,苏联西部阻塞高压发展、维持;季风中断期,西藏高原西部有高空槽存在;苏联西部阻塞高压减弱、崩溃或有高空槽发展;季风的撤退也与东亚冷空气活动关系密切。     

Absolute spectrophotometry of Neptune: 3390 to 7800 Å

Absolute spectrophotometry of Neptune from 3390 to 7800 Å, with spectral resolution of 10 Å in the interval 3390–6055 and 20 Å in the interval 6055–7800 Å, is reported. The results are compared with filter photometry (Appleby, 1973; Wamsteker, 1973; Savage et al., 1980) and with synthetic spectra computed on the basis of a parameterization proposed by Podolak and Danielson (1977) for aerosol scattering and absorption. A CH₄/H₂ ratio of is derived for the convectively mixed part of Neptune's atmosphere, and constrains optical properties of hypothetical aerosol layers.     

Species-specific patterns of aggregation of wild fish around fish farms

Fish-farming structures are widespread in coastal waters and are highly attractive to wild fish. Several studies have estimated that tons to tens of tons of wild fish aggregate around fish farms. These estimates assumed that the majority of wild fish are concentrated immediately beneath farms, although this assumption has never been explicitly tested. We tested the hypothesis that abundances of wild fish would be greatest immediately beneath farms and progressively diminish with distance at 4 full-scale coastal salmon (Salmo salar) farms in Norway. At each farm, fish were counted with a video-camera system at 5 different distances from the cages (farm = 0 m, 25, 50, 100 and 200 m) throughout the water column on three separate days. Combined across all locations and times, the total abundance of wild fish was 20 times greater at the farm than at the 200 m sampling distance. Saithe (Pollachius virens) dominated assemblages at all 4 farms and were consistently significantly more abundant at the farm than at the 25–200 m distances. This ‘tight aggregation’ around farms corresponds to the reliance of saithe on waste feed when they school near farms. In contrast, patterns of distribution of both cod (Gadus morhua) and poor cod (Trisopterus minutus) varied among farms, with either highest abundances at the farm or a more even distribution of abundance across all 5 distances sampled. No specific pattern of aggregation was evident for the bottom-dwelling haddock (Melanogrammus aeglefinus). Our results suggest that the present 100 m no-fishing zone around salmon farms protects the greatest proportion of farm-aggregated saithe and cod from fishing during the daytime. However, whether this reduces their overall susceptibility to fishing requires further research regarding nighttime distribution and movements.     

Bioindication of water and bottom sediment pollution in the Kondopozhskaya Bay of Lake Onega

The situation in the Kondopozhskaya Bay of Onega Lake, polluted by wastewater of a pulp-and-paper mill is considered. The dynamics of wastewater input over 80 years is analyzed; the rate of such input varied widely in this period because of changes in cellulose production processes. A close correlation was found to exist between the characteristics of the state of aquatic organism communities and the environmental physicochemical characteristics. The pollution indices of water mass and the bed are evaluated, including biological and physicochemical data. Those indices can be used to identify polluted zones of water and bottom sediments in Onega Lake subject to the discharge of wastewaters from pulp-and-paper mill.     

Simulation of the Holocene climate evolution in Northern Africa: The termination of the African Humid Period

The Holocene climate evolution in Northern Africa is studied in a 9000-yr-long transient simulation with a coupled atmosphere–ocean–vegetation model forced by changes in insolation and atmospheric greenhouse gas concentrations. The model simulates in the monsoonal domains a significant decrease in precipitation under influence of the orbitally forced reduction in summer insolation. In the Western Sahara region, the simulated mid-Holocene transition from humid to arid conditions (the termination of the African Humid Period) is highly non-linear with the occurrence of centennial-scale climate fluctuations due to the biogeophysical feedback between precipitation and vegetation cover. This result is in agreement with proxy data from the Western Sahara region. The other monsoonal regions experience a more gradual climate evolution that linearly follows the insolation forcing, which appears in disagreement with available lake level records.     

Temporal patterns and controls on runoff magnitude and solution chemistry of urban catchments in the semiarid southwestern United States

Urban expansion and the scarcity of water supplies in arid and semiarid regions have increased the importance of urban runoff to localized water resources. However, urban catchment responses to precipitation are poorly understood in semiarid regions where intense rainfall often results in large runoff events during the short summer monsoon season. To evaluate how urban runoff quantity and quality respond to rainfall magnitude and timing, we collected stream stage data and runoff samples throughout the 2007 and 2008 summer monsoons from four ephemeral drainages in Tucson, Arizona. Antecedent rainfall explained 20% to 30% of discharge (mm) and runoff ratio in the least impervious (22%) catchment but was not statistically related to hydrologic responses at more impervious sites. Regression models indicated that rainfall depth, imperviousness and their combined effect control discharge and runoff ratios (p < 0.01, r² = 0.91 and 0.75, respectively). In contrast, runoff quality did not vary with imperviousness or catchment size. Rainfall depth and duration, time since antecedent rainfall and event and cumulative discharge controlled runoff hydrochemistry and resulted in five specific solute response patterns: (i) strong event and seasonal solute mobilization (solute flush), (ii) event chemostasis and strong seasonal flush, (iii) event chemostasis and weak seasonal flush, (iv) event and seasonal chemostasis and (v) late seasonal flush. Our results indicate that hydrologic responses of semiarid catchments are controlled by rainfall partitioning at the event scale, whereas wetting magnitude, frequency and timing alter solute stores readily available for transport and control temporal runoff quality. Copyright © 2012 John Wiley & Sons, Ltd.     

A Raman spectroscopic study on the structural disorder of monazite–(Ce)

This study addresses whether Raman spectra can be used to estimate the degree of accumulated radiation damage in monazite-(Ce) samples whose chemical composition was previously determined. Our results indicate that the degree of disorder in monazite–(Ce), as observed from increasing Raman band broadening, generally depends on both the structural state (i.e., radiation damage) and the chemical composition (i.e., incorporation of non-formula elements). The chemical effects were studied on synthetic orthophosphates grown using the Li-Mo flux method, and non radiation-damaged analogues of the naturally radiation-damaged monazite–(Ce) samples, produced by dry annealing. We found that the “chemical” Raman-band broadening of natural monazite–(Ce) can be predicted by the empirical formula, $$ {\hbox{FWHM}} {\hbox{[c}}{{\hbox{m}}^{ - {1}}}{]} = {3}{.95} + {26}{.66} \times {\hbox{(Th}} + {\hbox{U}} + {\hbox{Ca}} + {\hbox{Pb)}} {\hbox{[apfu]}} $$ where, FWHM = full width at half maximum of the main Raman band of monazite–(Ce) (i.e., the symmetric PO₄ stretching near 970?cm^?1), and (Th+U+Ca+Pb) = sum of the four elements in apfu (atoms per formula unit). Provided the chemical composition of a natural monazite–(Ce) is known, this “chemical band broadening” can be used to estimate the degree of structural radiation damage from the observed FWHM of the ν₁(PO₄) band of that particular sample using Raman spectroscopy. Our annealing studies on a wide range of monazite–(Ce) reference materials and other monazite–(Ce) samples confirmed that this mineral virtually never becomes highly radiation damaged. Potential advantages and the practical use of the proposed method in the Earth sciences are discussed.