نشریه علوم دانشگاه خوارزمی
سال پنجم شماره 3 (پاییز و زمستان 1384)

A major part of structural studies is the analysis of elements of fold style. In this paper, the elements of main folds style in the Alborz – Central, Iran border zone, were investigated. In this respect, cylindricity, symmetry, style of a folded surface, style of a folded layer and style of a folded multilayer were evaluated. Finally, fold style characteristics and young history of folding in the studied area were indentified. In addition, two main mechanisms (Buckle and Detachment Folding) were distinguished.

Total streamflow on karstic watershed comprises tow main components in which total baseflow and direct runoff. The former components include groundwater discharge basically. The later component, the direct runoff component, consists of surface runoff resulted from precipitation. Separation of main components of total streamflow on karstic watershed has been performed by "HYSEP" software on bases of Zayandeh-Roud daily streamflow data for 15 Iranian calendar years from 1360-1361 to 1374-1375 water year as a case study. This software employs three methods to compute values of above-mentioned main components; separate by fixed interval method, sliding interval method and local minimum method. Comparison of results for above methods obviously shows a good agreement. So the difference of long term results (15 years) for total baseflow is always less than 2.7 %.

Baneh pluton is located in northwest of Kordestan province and Sanandaj-Sirjan zone. This body has been injected into low-grade metamorphic rocks in Cretaceous and so it is attributed to upper Cretaceous-Paleocene. This complex is composed of three distinct intrusive phases. These phases are diorite, biotite-granite and garnet-bearing granite. Diorites is the first constituent unit that is intruded by biotite granite in some areas. In other areas interaction of these two bodies is clear. Therefore, biotite granite has intruded simultaneousey with diorite or sometimes after it. Garnet-bearing granite is the youngest unit of this complex that usually intrudes as dyke in to biotite granite. There are hornblende, titanite and magnetite in diorites, also ASI>1, CIPW-normative diopside and high degree of CaO, Na2O, Sr suggest that diorite related to I-type granitoides. The aboundant existence of biotite, muscovite and surmicaceous enclaves in biotite granite and presence of garnet in garnet-bearing granite classify them under S-type group. Furthermore, ASI>1, CIPW-normative corundum and high degree of Rb, K2O is used as an evidence for this issue. From tectonic setting point of view,Baneh Pluton is located in VAG granitoides which is related to continental subduction zone. Geochemical data indicates that diorites originates from enriched mantle over the subduction zone or from subducted oceanic crust. Biotite granites and garnet-bearing granites are produced by fractional melting of metasedimentary rocks. Some biotite granites have a metapellitic origin and others are derived from metagreywacks where garnet-bearing granites are the product of fractional melting of metapellitic rocks.

Tubiphtes morronensis has been regarded as a community consisting of foraminifera (miliolid) and an overgrowth of some kind of algae or cyanobacteria. Although occurring in a wide variety of different facies, Tubiphtes morronensis represents a valuable marker fossil for environmental conditions. This is due to the ability of these foraminifera to adapt to different conditions by developing different growth forms. Important feature is the thickness of the outer test, apparently depending on the amount of light available for the algal symbiont. Shallow-water tests may show diameters of more than 1 mm, whereas the diameter of the outer test of deeper water forms strongly tends towards zero. In the Esfandiar Limestone Formation, the diameter of Tubiphtes morronensis is 0.7 mm to 1 mm and shows adaptations to shallow water environments.

Shekarnab intrusion is a part of an extensive magmatism in the Central Alborz Tectonic Zone of Iran. This intrusive body, which is mostly composed of monzonitic, gabbroic and syenitic lithologies, was intruded within green tuffs of the Karaj formation. These plutonic rocks show geochemical alkaline-potassic affinity and in the case of aluminum saturation index, they could be classified as meta-aluminous rocks. These rocks show Nb negative anomaly, enrichment of LILE and are depleted in HFSE. The spider and discrimination diagrams demonstrate that the parent magma of the plutonic intrusion could be related to a subduction zone and have emplaced in an active continental margin. Based on geochemical analysis of trace and major elements, as well as field and petrographical studies, it could be suggested that crystal differentiation has played an important role in lithological diversity of this intrusive body.

Efron's bootstrap method can only be used to estimate the precision measures of estimators when observations are independent. For spatial data that are spatially correlated, the moving block bootstrap method is usually used. But, in this method, the boundary observations have less chance of presence in blocks resampling than the other observations. In this paper, the new separate block bootstrap method is introduced and an algorithm is given for estimating the precision measures of estimators. A simulation study is carried out to compare the efficiency of the separate block bootstrap method with moving block bootstrap. It is shown that, with their method we can estimate the bias of sample mean with no error, and the estimator for variance of sample mean is consistent.