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161.
Helga de Wall Stefan Schöbel Manoj K. Pandit Kamal K. Sharma J. Just 《Journal of the Geological Society of India》2010,75(1):239-253
The Mirpur granite body represents a relatively small (10 km2) pluton intruded along the northern margin of the adjacent Mt. Abu batholith (∼125 km2) in NW India. It is a visibly undeformed alkali feldspar rich pink granite; in contrast, the Mt. Abu is a composite granitoid
body and variably deformed. Both are intruded by rhyolitic dykes and the terminal magmatic events in both the cases are mafic
dykes. The AMS (Anisotropy of Magnetic Susceptibility) data identify the Mt. Abu with SE-dipping foliations and subvertical
lineations as a single structural domain while the Mirpur granite body shows two domains characterized by predominantly E
— W trend of magnetic foliation in the eastern part (domain I) and N — S orientations in the western part (domain II). The
domain I shows magmatic fabrics, typical for the peraluminous granites of Malani Igneous Suite (MIS). Change in fabric orientation
in the domain II has resulted from cataclasis wherein the samples show destruction of the original E — W fabric and complete
transposition by N — S trends. The foliations in the Mt. Abu granites have been related to SE orientation of maximum horizontal
stress. The same maximum stress direction can be inferred from dyke orientation in the Mirpur granite, which is interpreted
as continuation of the tectonic imprint in this region during emplacement of both the granites. Age of the cataclastic overprint
with a predominant N — S orientation is not yet constrained but corresponds with the trend of the nearby Sindreth basin within
the Malani Igneous Suite. The Neoproterozoic tectonic scenario for the region has been interpreted in terms of an ongoing
crustal convergence and granitic magma emplacement against the back stop offered by the rigid Delhi Fold Belt. 相似文献
162.
163.
Deforestation and other Land Use and Land Cover (LULC) changes, driven by variety of physical and anthropogenic factors, have altered the mountainous environment. Mountains around the world including northern and north western belts of Pakistan are highly sensitive to deforestation and other LULC changes, which have profound impacts on various sectors of bio-physical and socio-economic systems. Assessment of LULC changes has high significance for protection, conservation and monitoring mountainous environment. The present study is an attempt to assess the landscape changes with particular reference to forest cover depletion in Kurram Agency located in the north western mountain belt of Pakistan. For detailed comparative analysis the study area has been divided into three sections, which coincide with the present administrative divisions of the Agency, i.e., Upper, Lower and Central Kurram. Temporal span of this study covers four decades. In this study, land use map of 1970 and land sat satellite imageries of 1987, 2000 and 2014 were used as spatial data sets. The images were processed and classified into six LULC classes through geospatial packages and change detection maps were prepared for each division and time period. Findings of the study reveal two trends in the four major LULC categories. Forest and rangeland have shrunk, on average, by 15% and 7.5% respectively while, bare soil and rocks outcrops have expanded by 89% and agriculture land by 7.2% in Kurram agency. The water bodies and snow cover have minor fluctuation in its land area. Major causes of shrinking greenery is attributed to high influx of Afghan refugees and high energy demand of growing population. However, with outflow of the refugees from Kurram agency the general trend in forest cover has reverted and deforestation rate has slowed down. 相似文献
164.
In this paper, we developed statistical method for distance determination of a stellar group. The method depends on the assumption that, the stars scatter around a mean magnitude in a Gaussian distribution. The mean apparent magnitude of the stars is then expressed in terms of the frequency function of the apparent magnitudes, so as to correct for observational incompleteness at the faint end. The problem reduces to the solution of a highly transcendental equation for a given apparent magnitude parameter α. Computational algorithm of the method is illustrated and the numerical solutions of the basic equation are given for some values of α . 相似文献