Cumulative Frequency Curves Research Articles

Análise estratigráfica e distribuição do arsênio em depósitos sedimentares quaternários da porção sudeste do Quadrilátero Ferrífero, bacia do Ribeirão do Carmo, MG

A região do QF, em Minas Gerais, tornou-se internacionalmente conhecida pela exploração de ouro no século XVIII. Nesse artigo, serão apresentados valores de referência (background) para o arsênio em sedimentos aluviais provenientes de áreas que foram intensamente afetadas pela exploração de ouro no passado, contidas na bacia do ribeirão do Carmo. A análise da sucessão faciológica dos perfis aluviais foi realizada em depósitos sedimentares de planícies de inundação, barrancos de rios (cutbank) e terraços aluviais e foi o alicerce para a obtenção do valor de referência do arsênio em depósitos de fácies de canal e de planícies de inundação. A partir do conhecimento do valor de referência obtido pelo método estatístico, com base na confecção de curvas de freqüência acumulada em escala linear, foram gerados mapas geoquímicos no sistema SIG. A obtenção do valor de referência e do mapa geoquímico do arsênio, na bacia do ribeirão do Carmo, com representação das áreas com concentrações anômalas desse elemento, é fundamental para o diagnóstico e planejamento ambiental de um distrito mineiro potencialmente contaminado por arsênio.

Contribution of dendrochronology to the determination of magnitude–frequency relationships for landslides

The determination of magnitude–frequency (M–F) relationships is necessary for landslide hazard assessment. Ideally, this is achieved by using inventories of past landslide events recorded by technical units or aerial photo interpretation. However, direct sources of landslide data are often unavailable. Dendrogeomorphological techniques allow us to determine the frequency of events, but few attempts have been made to estimate landslide magnitude by analysing the spatial distribution of disturbed trees. This paper addresses M–F determination for rockfalls, debris flows and complex slides obtained by dendrogeomorphology. The cases presented require the appropriate understanding of both the geomorphological context and the disturbance caused by landslide motion on trees. Both small and large rockfalls can be identified and dated by reconstructing the trajectories in the forest stand. The larger the rockfall size, the longer the path, the higher the number of affected trees and the greater the area of deposition of rock fragments. The area of damaged trees is proposed as an indicator of the rockfall magnitude. The frequency and extent of a series of debris flows were reconstructed by mapping their deposits using relative dating criteria and by dating damaged trees. Local and global mudslide reactivations were deduced by sampling various tree generations and by analysing the location of the disturbed trees in the landslide units. Magnitude–cumulative frequency curves were determined for the three cases.

Metal endowment of cratons, terranes and districts: Insights from a quantitative analysis of regions with giant and super-giant deposits

This paper discusses the spatial distribution of gold, uranium, and base metal (copper, lead and zinc) endowment of mineralized regions. Cumulative frequency curves (called endowment curves) are used to characterize metal endowment of cratons, of terranes within cratons and of districts within terranes. The analysis shows that the endowment curves of cratons, terranes and districts which contain super-giant deposits differ from those which do not host such deposits. On size (tonnage of metal, x-axis) vs. quantile (%, y-axis) plots the endowment curves of cratons, terranes and districts with high endowment (hosting giant or super-giant deposits) display a uniform shift in the direction of larger deposits. The shift is generally uniform indicating that even smaller deposits in cratons, terranes and districts with high endowment are larger than those in cratons, regions and districts with relatively low endowment. This supports the conclusion that craton- and terrane-scale features most probably determine the metal endowment of both high- and low-endowment regions. The difference in the metal endowment of cratons, terranes and districts reflect the difference in the intensity and duration of metal accumulation caused by a much larger system of energy and mass flux (i.e., mineral system). Mineral districts with a single giant or super-giant deposit represent areas where the mineral system was not only fertile but highly focused or concentrated. Head/total and head/tail metal ratios in mineral districts provide an estimate of how focused the mineral system was in a particular area.

Two-Year Clinical, Angiographic, and Intravascular Ultrasound Follow-Up of the XIENCE V Everolimus-Eluting Stent in the Treatment of Patients With De Novo Native Coronary Artery Lesions: The SPIRIT II Trial

Two-Year Clinical, Angiographic, and Intravascular Ultrasound Follow-Up of the XIENCE V Everolimus-Eluting Stent in the Treatment of Patients With De Novo Native Coronary Artery Lesions: The SPIRIT II Trial

Impact of sleep on arrhythmogenesis.

Sleep is generally considered to be a protected period, when the cardiovascular system benefits from the restorative influences of the sleeping brain. However, the dynamics of cardiovascular control during sleep can tax the capacity of the diseased coronary circulation and myocardium with surges in sleep-state–related autonomic activity and disruptions in airway function and central nervous system regulation. In this regard, sleep may constitute an autonomic stress test for the heart. The scope of sleep-related risk for atrial and ventricular arrhythmias is substantial. The major subgroups susceptible to adverse influences of surges in autonomic activity during sleep are those with ischemic heart disease, heart failure, and channelopathies (Table).1 It is significant that 20% of myocardial infarctions and 15% of sudden deaths occur at night in the United States.2 Most atrial arrhythmias in patients younger than 61 years of age have nocturnal onset.3 The young are not immune to risk, as sudden infant death syndrome (SIDS) claims 2500 lives in the United States annually.4 Cardiovascular risk is compounded by comorbid factors, most notably apnea, which affects an estimated 4% to 9% of the general population5 and is considerably more prevalent among obese individuals.6 The more common form is obstructive sleep apnea (OSA), with partial or complete collapse of the pharynx. Half of heart failure patients experience either OSA or central sleep apnea (CSA) with central nervous system–mediated periodic breathing, commonly referred to as Cheyne-Stokes respiration. Such cardiorespiratory disturbances profoundly alter autonomic nervous system activity and increase risk of arrhythmia, hypertension, and myocardial infarction. View this table: Table. Patient Groups at Potentially Increased Risk for Nocturnal Cardiac Events It is surprising, as recently underscored by Malhotra and Loscalzo,7 that the significance of cardiovascular risk during sleep may not be duly recognized within the cardiology community. The reasons are …

호박과실파리 발생생태 및 계절초기 성충우화시기 예찰 모형

호박과실파리(Bactrocera depressus)는 파리목 과실 파리과에 속한 곤충으로 박과류 작물의 중요한 해충이다. 이 연구는 호박과실파리의 호박 피해관련 기초생태를 구명하고 성충우화시기 예찰모형을 개발하고자 수행하였다. 애호박 생산농가에서 호박과실파리 산란 흔적은 7월 중하순부터 발생되기 시작하여 8월 하순 최성기를 보였으며 9월 하순부터는 발견되지 않았으며, 이 기간이 호박과실파리 산란활동 시기로 판단되었다. 숙과호박 농가에서는 7월 하순 어린 과실에 산란 흔적이 발견되었고 8월 이후 유충에 의한 호박의 부패가 시작, 10월까지 피해과가 급격히 증가하였다. 호박과실파리 산란흔적은 호박 과실 당 평균 2.2개가 발견되었으며, 과실 당 <TEX>$28.8{\sim}29.8$</TEX>개의 산란수를 보였다. 우화트랩으로 조사한 호박과실파리 월동번데기의 우화시기는 초발일이 5월 중순에서 하순 사이로 나타났고, 최성기는 5월 하순 내지 6월 상순이었다. 호박과실파리 월동번데기의 우화까지 발육기간은 <TEX>$15^{\circ}C$</TEX>에서 59.0일, <TEX>$20^{\circ}C$</TEX> 39.3일, <TEX>$25^{\circ}C$</TEX> 25.8일, <TEX>$30^{\circ}C$</TEX> 21.4일이었고 <TEX>$35^{\circ}C$</TEX>에서는 발육하지 못하였다. 온도와 월동번데기 발육기간 관계에 대한 선형모형 추정결과는 발육영점온도는 <TEX>$6.8^{\circ}C$</TEX>로 추정되었고 발육완료에 필요한 적산온도는 482.3 DD 이었다. 또한 월동번데기 발육률과 온도와 비선형적 관계는 Gaussian 모형으로 잘 설명되었다. 적산온도 모형으로 50% 성충우화일을 예측한 결과 실측치와 편차가 1일로 적중률이 높았다. 또한 발육모형과 발육완료시기 분포모형(Weibull 함수)을 이용한 발율률 적산모형의 예측치는 실측치의 우화양상과 유사하였다. 본 연구결과는 향후 호박과실파리의 관리전략 수립에 유용하게 이용될 수 있을 것으로 기대된다. The pumpkin fruit fly, Bactrocera depressa (Tephritidae: Diptera), is one of the most important pests in Cucurbitaceae plants. This study was conducted to investigate the basic ecology of B. depressa, and to develop a forecasting model for predicting the time of adult emergence in early season. In green pumpkin producing farms, the oviposition punctures caused by the oviposition of B. depressa occurred first between mid- and late July, peaked in late August, and then decreased in mid-September followed by disappearance of the symptoms in late September, during which oviposition activity of B. depressa is considered active. In full-ripened pumpkin producing farms, damaged fruits abruptly increased from early Auguest, because the decay of pumpkins caused by larval development began from that time. B. depressa produced a mean oviposition puncture of 2.2 per fruit and total 28.8-29.8 eggs per fruit. Adult emergence from overwintering pupae, which was monitored using a ground emergence trap, was first observed between mid- and late May, and peaked during late May to early June. The development times from overwintering pupae to adult emergence decreased with increasing temperature: 59.0 days at <TEX>$15^{\circ}C$</TEX>, 39.3 days at <TEX>$20^{\circ}C$</TEX>, 25.8 days at<TEX>$25^{\circ}C$</TEX> and 21.4 days at <TEX>$30^{\circ}C$</TEX>. The pupae did not develop to adult at <TEX>$35^{\circ}C$</TEX>. The lower developmental threshold temperature was calculated as <TEX>$6.8^{\circ}C$</TEX> by linear regression. The thermal constant was 482.3 degree-days. The non-linear model of Gaussian equation well explained the relationship between the development rate and temperature. The Weibull function provided a good fit for the distribution of development times of overwintering pupae. The predicted date of 50% adult emergence by a degree-day model showed one day deviation from the observed actual date. Also, the output estimated by rate summation model, which was consisted of the developmental model and the Weibull function, well pursued the actual pattern of cumulative frequency curve of B. depressa adult emergence. Consequently, it is expected that the present results could be used to establish the management strategy of B. depressa.

Combining Multiple Quantitative and Qualitative Goals When Assessing Biomanufacturing Strategies under Uncertainty

This paper reports how financial and operational results from bioprocess simulations can be combined with other criteria pertinent to decision-making predictions to provide a more holistic approach to the evaluation of biomanufacturing alternatives. The classical additive weighting method, which is a multiattribute decision-making technique that can account for both the quantitative and qualitative parameters that ultimately need to be considered, is used. Its application is demonstrated through a case study that addresses whether start-up companies should invest in a stainless steel pilot plant or use disposable equipment for the production of early phase clinical trial material. The technique is extended to allow for uncertainty in parameters. An illustration of its use to compare alternatives based on cumulative frequency curves of the aggregate scores is provided. For cases where it is difficult to discriminate between the options, plots of risk versus reward are shown to be useful for identifying the best alternative based on the risk preference of the company's management.

Geochemical baseline of trace elements in the sediment in Dexing area, South China

A baseline might be used as a point of reference to monitor change from some specific data without concern for whether the baseline determination is natural or has been changed by human activity. We selected 326 sediment samples from Dexing area, South China, and analyzed for 17 chemical elements. The geochemical baseline was predicted with the method of the normalization procedure combined with the relative cumulative frequency curve. The results indicate Al was the best reference element for the normalization procedure among four potential reference elements (Al, Fe, Ti, and Mn). The baseline value range obtained from the normalization procedure method included both the regional geochemical background of the sediment and the median value of the measured contents. The median value of baselines obtained from relative cumulative frequency method was lower than that obtained from normalization procedure method. In contrast to the geochemical patterns of heavy metals in 1987, the spatial distribution of anomalies sprawled in 2004 in study area, especially for Cu, Pb, Zn, Cd, As, Fe, and Cr.

USING THE TRANSPIRATION REGIME TO ESTIMATE BIOMASS PRODUCTION

The design and implementation of a new or improved irrigation or drainage system should be preceded by a study of the soil water regime (SWR) to define the need for such a system and to optimize its design. This requires estimates of appropriate parameters characterizing the long-term (multiyear) dynamics of the SWR and its relation to biomass production. Parameters that could be used for this purpose are the water content or pressure head at one or several points in the soil root zone or the average water content of the root zone, as affected by precipitation and evapotranspiration or other variables. Because these variables change from year to year, it is necessary to characterize somehow statistically the SWR during a relatively long period. Because the water content is not easily related directly to biomass production, we used the calculated seasonal transpiration rate as an indirect characteristic of the canopy water regime. This article presents a method for estimating plant production as a function of the seasonal transpiration rate as calculated retrospectively with the HYDRUS-ET software package. New in our approach is the use of an empirical relationship between seasonal transpiration and yield. The cumulative frequency distribution of seasonal transpiration was chosen as the basic characteristic of the SWR as a source of water for plants. The approach allows one to estimate cumulative frequency curves of actual and potential yields. The difference between these two curves is the cumulative frequency distribution of yield to be optimized by the irrigation system. The method permits a better cost-benefit analysis by comparing expected yield increases with the investment and operational expenses of the newly designed irrigation system, or of newly invoked water management practices. The approach is illustrated using a 31-year time series of data for a corn crop (Zea mays L.) grown on loess soil in Slovakia.

Increased thermoregulation in cold-exposed transgenic mice overexpressing lipoprotein lipase in skeletal muscle: an avian phenotype?

LPL is an enzyme involved in the breakdown and uptake of lipoprotein triglycerides. In the present study, we examined how the transgenic (Tg) overexpression of human LPL in mouse skeletal muscle affected tolerance to cold temperatures, cold-induced thermogenesis, and fuel utilization during this response. Tg mice and their nontransgenic controls were placed in an environmental chamber and housed in metabolic chambers that monitored oxygen consumption and carbon dioxide production with calorimetry. When exposed to 4 degrees C, an attenuation in the decline in body temperature in Tg mice was accompanied by an increased metabolic rate (15%; P < 0.001) and a reduction in respiratory quotient (P < 0.05). Activity levels, the expression of uncoupling proteins in brown fat and muscle, and lean mass failed to explain the enhanced cold tolerance and thermogenesis in Tg mice. The more oxidative type IIa fibers were favored over the more glycolytic type IIb fibers (P < 0.001) in the gastrocnemius and quadriceps muscles of Tg mice. These data suggest that Tg overexpression of LPL in skeletal muscle increases cold tolerance by enhancing the capacity for fat oxidation, producing an avian-like phenotype in which skeletal muscle contributes significantly to the thermogenic response to cold temperatures.

The Soil Geochemical Atlas of Portugal: Overview and applications

The continental area of Portugal is now entirely covered by a soil geochemical survey (1 site/135 km 2), taking as the sampling media topsoils (upper mineral horizons, A) and organic horizons (humus, O). Standard methods for sampling, sample preparation and analysis were used in order to achieve high quality and consistent data. Each sample was analyzed for 32 chemical elements, pH, electrical conductivity and organic matter content. The main purpose of the survey was to obtain baseline levels for various chemical elements. The compilation of all data (nearly 45,000 individual data) in an organised way, led to the production of the first Soil Geochemical Atlas of Portugal. In this Atlas it is possible to find for each chemical element a set of information statistics (basic statistical parameters, boxplots, cumulative frequency curves, etc.), maps of spatial distribution, among other information of geochemical and environmental interest. This paper gives an overview of the Soil Atlas and examples of application. The data were used to calculate reference values for 9 elements of environmental importance and to obtain empirical formulae allowing the estimation of elements in the coarse fraction of soils (< 2.00 mm) from known concentration in a finer fraction (< 0.18 mm).

Partitioned multiobjective risk modeling of carcinogenic compounds in groundwater

Quantifying human cancer risk arising from exposure to contaminated groundwater is complicated by the many hydrogeological, environmental, and toxicological uncertainties involved. In this study, we used Monte Carlo simulation to estimate cancer risk associated with tetrachloroethene (PCE) dissolved in groundwater by linking three separate models for: (1) reactive contaminant transport; (2) human exposure pathways; and (3) the PCE cancer potency factor. The hydrogeologic model incorporates an analytical solution for a one-dimensional advective–dispersive–reactive transport equation to determine the PCE concentration in a water supply well located at a fixed distance from a continuous source. The pathway model incorporates PCE exposure through ingestion, inhalation, and dermal contact. The toxicological model combines epidemiological data from eight rodent bioassays of PCE exposure in the form of a composite cumulative distribution frequency curve for the human PCE cancer potency factor. We assessed the relative importance of individual model variables through their correlation with expected cancer risk calculated in an ensemble of Monte Carlo simulations with 20,000 trials. For the scenarios evaluated, three factors were most highly correlated with cancer risk: (1) the microbiological decay constant for PCE in groundwater, (2) the linear groundwater pore velocity, and (3) the cancer potency factor. We then extended our analysis beyond conventional expected value risk assessment using the partitioned multiobjective risk method (PMRM) to generate expected-value functions conditional to a 1 in 100,000 increased cancer risk threshold. This approach accounts for low probability/high impact outcomes separately from the conventional unconditional expected values. Thus, information on potential worst-case outcomes can be quantified for decision makers. Using PMRM, we evaluated the cost-benefit relationship of implementing several postulated risk management alternatives intended to mitigate the expected and conditional cancer risk. Our results emphasize the importance of hydrogeologic models in risk assessment, but also illustrate the importance of integrating environmental and toxicological uncertainty. When coupled with the PMRM, models integrating uncertainty in transport, exposure, and potency constitute an effective risk assessment tool for use within a risk-based corrective action (RBCA) framework.

Background arsenic concentrations in Southeastern Spanish soils

The arsenic content in the province of Granada (SE Spain) was quantified, based on 93 soils at two different depths and their corresponding parent materials. The arsenic concentrations fit a log-normal distribution. Four different statistical procedures to estimate the arsenic background range in the region were tested. Upper background limits clearly exceeded limits reported for natural soils when based on the Tukey box plot or means and standard deviations of the dataset (M+/-2sdev) or of the calculated distribution function (Mf+/-2sigma) but not when based on median values (Md+/-2MAD). The relative cumulative frequency curve not only adequately estimates the background range but also delivers a clear and detailed visualisation of the data distribution and identifies subpopulations with specific background ranges related to combinations of parent materials and degree of soil development.

Defining the geochemical baseline: a case of Hong Kong soils

A geochemical baseline provides the means to distinguish between the pedogenic origin and the anthropogenic origin of the trace element in the environmental compartments. We collected 271 soil samples representative of different parent rocks and soil types from the whole territory of Hong Kong and analyzed the composition of clay mineralogy and the contents of 15 chemical elements (Fe, Cd, As, etc.) for these samples. The baseline was predicted with the method of the normalization procedure combined with the relative cumulative frequency curve. The result indicated that Fe was the best reference element for the normalization procedure among the five potential reference elements (Fe, Al, Sc, Ti, and Mn), followed by Sc and Ti. A poor correlation was found between Sc, Ti, and Cu. The predicted baseline was much lower than the A-value of the Dutch List used usually in screening the polluted soil of Hong Kong, implying that the extent of heavy metal pollution might have been underestimated with respect to local lands. We also applied the cluster analysis to distinguish the geochemical associations of the trace elements due to its importance to the baseline. Approximately three major associations including the Fe–Mn-oxides related, Al oxides or Al-bearing-clay-mineralogy related and sulfide- related associations were observed from the dendrogram.

SYSGRAN: UM SISTEMA DE CÓDIGO ABERTO PARA ANÁLlSES GRANULOMÉTRICAS DO SEDIMENTO

SysGran is an easy-to-use specific software for granulometric analysis of sediments, which includes a rich graphical output. The software is now available under GNU license, meaning that it is free for any use and can be freely modified and improved. The software has been designed to maximize speed of analysis and is able to analyze hundreds of samples in a few seconds, together with many types of graphics. The results of statistical analysis of the sediment includes Folk &amp; Ward graphical methods (among others) as well as methods of moments (mean, median, sorting, skewness, curtosis), grain size fractions (gravel, sand, silt and clay percentages), verbal classification, main percentile units and data for cumulative frequency curve plot using other graphical softwares.

Regional delimitation of the Elbe River basin based on flood seasonality analysis

The study presents approaches that can be used for assessing flood seasonality in the Czech part of the Elbe River basin. For each of the selected gauging stations, a graphic-numerical method based on flood cumulative frequency curves was applied for identification of intervals, during which the probability of seasonal flood occurrence was high. The results were used for classification of the individual catchments into seven regions specific in terms of the flood seasonality.

The Effects of Scrubber Installation at the Navajo Generating Station on Particulate Sulfur and Visibility Levels in the Grand Canyon

Grand Canyon National Park (GCNP) is a mandatory Class I federal area that is afforded visibility protection under the Federal Clean Air Act. In this paper, we have examined the effects on visibility and particulate sulfur (Sp) at GCNP as a result of reducing sulfur dioxide (SO2) emissions by 90% from the Navajo Generating Station (NGS). Scrubbers were retrofitted to each of the three units at NGS during 1997, 1998, and 1999. The Inter-agency Monitoring of Protected Visual Environments aerosol network database affords us an opportunity to examine trends in Sp and extinction both prescrubber and postscrubber. The NGS impacts GCNP primarily during the winter (December to February). During winter, at times, there are fogs, stratus, and high-relative humidity in the Grand Canyon. When the NGS plume interacts with these fogs and stratus, rapid conversion of SO2 to Sp can occur. A variety of analytical techniques were used, including cumulative frequency plots of Sp and extinction, and chemical mass balance and tracer source apportionment analysis. We also deployed P value statistical analysis of “extreme” Sp values. Before scrubbers were installed, values of Sp approaching 2 µg/m3 were occasionally observed. Because scrubbers have been installed, high levels of Sp have been markedly reduced. Statistical P value analysis suggests that these reductions were significant. Furthermore, we have also observed that Sp has been reduced throughout the cumulative frequency curve during winter by ~33% since scrubbers were installed. By contrast, during summer when the NGS impact on the Canyon is minimal, there has been only a relatively small decrease in Sp.

Textural Equilibrium in Magmatic Layers of the Lough Fee Ultramafic Intrusion, NW Connemara, Ireland: Implications for Adcumulus Mineral Growth

Small-scale magmatic layers in a minor ultramafic intrusion at Lough Fee, NW Connemara, Ireland, exhibit superb examples of primary adcumulate textures. Two of these monomineralic layers are quantitatively analysed to establish their degree of textural equilibrium. A series of apparent dihedral angles is measured from threegrain junctions, and cumulative frequency curves are plotted for each layer. The curves are compared to theoretical curves for equilibrated and unequilibrated rocks to determine the degree of textural equilibrium of each layer. The results show apparent dihedral angle values that closely approximate those of a system in local textural equilibrium. The importance of adcumulus growth in the development of magmatic layering and the implications of this process for layer formation are briefly discussed with reference to the tectonic setting of the intrusion, and it is concluded that magmatic layering may have developed in a syn-tectonic intrusion.

Textural Equilibrium in Magmatic Layers of the Lough Fee Ultramafic Intrusion, NW Connemara, Ireland: Implications for Adcumulus Mineral Growth

Small-scale magmatic layers in a minor ultramafic intrusion at Lough Fee, NW Connemara, Ireland, exhibit superb examples of primary adcumulate textures. Two of these monomineralic layers are quantitatively analysed to establish their degree of textural equilibrium. A series of apparent dihedral angles is measured from threegrain junctions, and cumulative frequency curves are plotted for each layer. The curves are compared to theoretical curves for equilibrated and unequilibrated rocks to determine the degree of textural equilibrium of each layer. The results show apparent dihedral angle values that closely approximate those of a system in local textural equilibrium. The importance of adcumulus growth in the development of magmatic layering and the implications of this process for layer formation are briefly discussed with reference to the tectonic setting of the intrusion, and it is concluded that magmatic layering may have developed in a syn-tectonic intrusion.

Textural Equilibrium in Magmatic Layers of the Lough Fee Ultramafic Intrusion, NW Connemara, Ireland: Implications for Adcumulus Mineral Growth

Small-scale magmatic layers in a minor ultramafic intrusion at Lough Fee, NW Connemara, Ireland, exhibit superb examples of primary adcumulate textures. Two of these monomineralic layers are quantitatively analysed to establish their degree of textural equilibrium. A series of apparent dihedral angles is measured from threegrain junctions, and cumulative frequency curves are plotted for each layer. The curves are compared to theoretical curves for equilibrated and unequilibrated rocks to determine the degree of textural equilibrium of each layer. The results show apparent dihedral angle values that closely approximate those of a system in local textural equilibrium. The importance of adcumulus growth in the development of magmatic layering and the implications of this process for layer formation are briefly discussed with reference to the tectonic setting of the intrusion, and it is concluded that magmatic layering may have developed in a syn-tectonic intrusion.