塔中Ⅲ区碳酸盐岩储层去泥质反演及泥质充填判别

塔里木盆地塔中Ⅲ区奥陶系碳酸盐岩储层是近年来勘探重点区域,良里塔格组储层内沉积泥质灰岩条带,以及一间房组洞穴顶部存在的沉积泥质条带,给储层预测带来了较大难度。为提高储层预测精度,分析奥陶系良里塔格组和一间房组储层内泥质展布规律,建立沉积泥质灰岩条带背景纵波阻抗体,完成了无井约束叠后地质统计学反演。研究结果表明,无井反演储层预测纵向发育位置、储层级别和已钻井吻合较好。利用叠前同时反演得到纵横波速比,通过纵波阻抗与纵横波速比交会图分析法,划分了一间房组优质储层、泥质充填储层、基质灰岩分布区间,对洞穴型储层泥质充填、叠前流体预测反演进行探索,确保储层预测的可靠性。     

First results obtained with DENIS

We briefly report on the first astronomical results obtained with the DENIS camera at the ESO 1 meter telescope.     

Dynamics of an Abra alba population (bivalve-scrobiculariidae) in the Bay of Brest

The Abra population studied, lived in a muddy-sand Melinna palmata community in the vicinity of the harbour of Brest. There were two periods of spawning in the year: June to August and end of autumn. Individuals 12 mm long can spawn after the first winter. Recruitment was regularly observed in 1 mm mesh sieves in May and September–October. Growth rings were formed in winter; a second growth ring in summer was correlated with spawning. The modal analysis showed a decreasing growth rate and maximum length for the successive cohorts over the three years surveyed. Growth characteristics observed in this population seem to be due to disturbances brought about by neighbouring dredgings which had just ended at the beginning of the study.     

Remarks on the homogeneity of a sample used to determine the Hubble parameterH 0

In a recent series of papers, Sandage and Tammann reach the conclusion according to which the Hubble constant is everywhere the same. This result arises from the analysis of two samples (a nearby one and a remote one) of Sc-type galaxies, each sample separately giving the same <H ₀> mean value. We attempt to check whether or not the whole data from both the samples together are consistent with theH ₀=constant hypothesis at a suitable level of statistical significance.     

The Cretaceous–Tertiary transition in Guatemala: limestone breccia deposits from the South Petén basin

Limestone breccia deposits in southern Mexico, Guatemala and Belize have recently been interpreted as proximal to distal ballistic fallout deposits, generated by a bolide impact that struck Yucatan at K/T boundary time. We review the age, lithology and the depositional environment of five K/T boundary sections in the South Petén area of Guatemala (Caribe, Aserradero, Chisec, Actela, Chemal) in order to evaluate the nature and origin of K/T limestone breccia deposition. The sections are located 500?km south of the proposed impact site at Chicxulub and trend in an east–west direction from the Guatemala/Mexico border to southern Belize. In four of the five sections examined, a breccia unit up to 50?m thick overlies reef-bearing shallow-water limestones of late Cretaceous (Campanian-Maastrichtian) age. Rhythmically bedded limestones, marls and siltstones of early Danian age overlie the breccia and were deposited under middle-to outer-neritic conditions. The breccia consists of differently coloured layers of shallow-water limestones. Clast size generally decreases upsection to thin layers of predominantly rounded clasts, and these fine-grained rudstones grade into grainstones at the top. In at least one section (EI Caribe) diagenetically altered glass spherules are present in the uppermost layers of the grainstone. These glass spherules are of stratigraphic position and chemical composition similar to black and yellow glass from Beloc, Haiti and Mimbral, Mexico, which some workers have chemically linked to melt glass within the breccia of the Chicxulub cores. We suggest that breccia deposition in Guatemala may have been multi-event, over an extended time period, and related to the collision of the Yucatan and Chortis plates as well as related to a major impact or volcanic event at the end of the Cretaceous.     

关于L—Fuzzy子群

本文利用模型子群概念，引入了Ｌ－Ｆｕｚｚｙ子群概念。基于模糊集合的层次结构特征，得到Ｌ－Ｆｕｚｚｙ了群若干重要性质；给出并证明Ｌ－Ｆｕｚｚｙ子群的一系列等价刻划；文章最后讨论Ｌ－Ｆｕｚｚｙ子群同态性质 。     

The effects of source rocks and chemical weathering on the petrogenesis of siliciclastic sand from the Neto River (Calabria, Italy): implications for provenance studies

Plutonic and gneissic rocks of the Sila Massif in the uppermost portion of the Neto drainage basin (Calabria, Southern Italy) weather and erode under a humid Mediterranean climate. During the development of weathering profiles, a combination of chemical weathering and granular disintegration processes occurred. Chemical weathering involves a loss of both plagioclase (mainly during grus generation) and K-feldspar (mainly during soil formation). This loss is attributed to transformation of plagioclase to clay minerals and to leaching and dissolution of K-feldspar. Sand composition is quartzofeldspathic and nearly homogeneous along the main channel of the Neto River, even where the river cuts across a blanket of sedimentary cover. Thus, fluvial transport does not alter sand composition within the Neto drainage basin. Petrographic indices are effective in (1) discriminating between contributions from similar (granite and gneiss) source rocks (Qm/F); (2) relating the provenance of plutoniclastic and gneissiclastic sand found in the headwaters to grus horizons (Qm/F; Q/Rg); and (3) distinguishing between upstream first-cycle and downstream multicycle sand (Q/Rg). This last distinction is further emphasized by considering both aphanitic and phaneritic varieties of rock fragments (RgRmRs diagram). Chemical weathering is the main sand producer within the regolithic environment in northern Calabria. In addition, rapid erosion resulting from steep slopes removes weathered products, and rapid and short transport leads to minimal sediment maturation. In general, the F/Q index is climate and relief dependent; thus, it should be used in conjunction with palaeoclimatic and palaeophysiographic evidence for provenance interpretations of ancient quartzofeldspathic sandstones.     

On barotropic and baroclinic tides over an arbitrary sloping topography

Some theoretical concepts about the frictionless dynamics of propagation of the barotropic tide over two-dimensional continental slopes of arbitrary shape are developed. A numerical procedure which generalizes the exact solution obtained over a rectilinear sloping topography is given. This technique can be applied to compute the harmonic components of the barotropic tide everywhere over sloping bottom contours of any shape. It permits in particular the avoidance of discontinuities at the boundaries of rectilinear-continental-slope profiles. The barotropic tidal results are used afterwards to calculate the barotropic forcing for the generation of internal tides. Numerical experiments are performed to study the interaction between the tide and some typical sloping topographies. A three-layered model is used for this purpose. Results are compared with those previously obtained over a rectilinear continental slope.     

A Model of PCB Bioaccumulation in the Sea Bass Food Web from the Seine Estuary (Eastern English Channel)

A bioaccumulation model was developed to simulate the PCB contamination in the sea bass food web from the Seine Estuary. The model relies upon a contaminant mass balance budget for each biological species. Biological processes determine the extent of bioaccumulation: respiration and feeding rates control the uptake of contaminants whereas excretion, spawning, and growth act on the chemicals removal. A step-by-step modelling approach was followed. A first version was a steady-state model validated for the bioaccumulation processes. In the second version seasonal variation was taken into account, and finally in the third version, the model was coupled with a population dynamics model to describe PCB contamination in each age class.