The previous viewpoint considered that,the early Tarim basin was an unified carbonate platform,its slope was developed along the Gucheng-Lunnan area.Based on sedimentologic and seismic stratigraphic data from the lower-middle Ordovician,deep-water slope and basinal facies were recognized along the MJ1-TZ29 section,so that the Tazhong and its adjacent areas could have already been isolated from the unified carbonate platformand seprated into three platforms of Tazhong-Bachu,Gucheng and Tangnan,which was also faced with TaBei area across a trough.The high-energy reef-shore bodies bandingly developed among the edge of each isolated platform as a band,which were mainly composed of mid-high energy grain banks.Inwards,it becomes the deposition of platform,developing the subphases of intraplatform banks,intraplatform depression and interabeach seas and soon.Outwards it becomes deeper-water deposition area of slope-trough.Under this circumstance,the new regional depositional pattern of the Tazhong and adjacent areas has been established.This new pattern has great theoretical and realistic significance for the establishment of new favourable exploration zones.It also greatly increases the strategic position for the petroleum exploration in lower Ordovician of research area.

The present paper is aimed to introduce our research into the effect of the crowded people density on the crushing fatalities.As is known,previous studies have identified the crowd density as the main risk factor leading to such crushing tragedies.In this paper,we have explored the crush fatalities of pedestrians in terms of the density of the crowd while referring to the continuous crowd flow model proposed by Hughes from Australia.According to the feature in different densities of the crowd,we can analyze the crushing accidents based on the here-introduced flow model proposed by Hughes.However,the maximum tolerance limits of the crowd density are also variable,which depend strongly on the physical characteristics of the crowd,or the crowd of pedestrians in particular involved.Integrating the realistic conditions of the Chinese crowd features,we assume the following 9 ped/m2 as the Chinese max tolerable crowd densities.Consequently,it can be concluded that the model helps to identify the dangerous locations for a crushing accident likely to be taking place.And,in turn,the model proves significant to avoid such accidents and ensure safety of the crowd gathering.

The present paper is aimed at introducing the authors' study on the mathematical relation between the consequences of explosive terrorist attacks and the crowd massing situations.Utilizing the geometric and probability theory,the paper has established a casualty mathematical simulation model in which the casualties are likely to be brought about mainly by the explosive debris in most suicide bombing events.Rather,different ways of the massing crowd may account for such casualties.Suppose the load of the explosive is given,let the number of the people gathering(m=10,20)and the angle of air disperse(α=10°,60°)be the variable for the explosion consequence,respectively,the study results indicate that the size of the crowd massing can be analyzed from the angle of the explosive debris and the effect of the arena size on the casualty.When the total number of the crowd reaches a certain threshold,the expected casualties would lower correspondingly.At the same time,it can be found that the casualties would drop with the explosive disperse angle.Furthermore,the paper has given a detailed discussion of the size of the arena that also affects the consequence of the casualties.If the area of the arena increases,the casualties would rise at first,and then drop.The results can be used to reduce the casualties in the similar events.

As the development of cities becomes more quick, the accidents happened in public venues resulted form massing crowd become more and more. This paper uses social risk to quantify the risk. On one hand, in terms of former research outcome, the paper deems that the occurrences of the accidents in public venues, in a time span, can be described as Poisson distribution, and then, the quantitative model of accident occurrence probabilities can be reasonal out. On the other hand, through the sum of the occurrences of accidents of different severity level, which is to embody the situational probability of accidents of different severity level with its frequencies, the outcome of accidents mortalities will be obtained, which is used to figure out the probabilities of the accidents of different casualty numbers. In the end, the F - N curve will be achieved. To use the F - N curve, it is able to analyse the social risk of crowd massing venues. Taking some statistical accidents as references, it describes how to use the model. The result proves the model is reasonable and accurate to a certain extent.