نتایج جستجو برای: tectonic cycles
تعداد نتایج: 100381 فیلتر نتایج به سال:
The progressive development of the Precambrian organic world was superimposed by epochs intense accumulation matter in marine sediments and formation carbonaceous formations, which differentiated section into submegacycles at intervals ~600, 400, 300, 100 Ma, reflecting trend biomass growth over time from Archaean to Vendian ( Ediacaran). In Phanerozoic, 26 stratigraphic levels bituminous combu...
quantitative assessment of relative tectonic activity in the alamarvdasht river basin, south of iran
tectonic processes are major factors controlling landform development in tectonically active areas. in order to evaluate quantitative measurement of tectonic activities in the alamarvdasht basin in the south of iran, six different morphological indices including stream-gradient index (sl), drainage basin asymmetry (af), hypsometric integral (hi), valley floor width-valley height ratio (vf), dra...
the paper deals with the analysis of the external factor (solar activity, volcanic eruptions) influence on tree growth at the kola peninsula, northwestern russia. pinus sylvestris l. (scots pine) tree-ring chronologies collected nearby the northern timberline (68.63n, 33.25e) include the oldest (1445-2005 ad) living pine tree found up to date in the kola peninsula. a total of 18 living trees p...
the study area is located in the northeast of iran. miankuhi formation is 500m thick and comprises homogeneous shales, brown granular sandstone and siltstone. in this study, 45 samples were taken from miankuhi shales and sandstones in order to determine their tectonic origin by using a polarizing microscope. samples were analysed by x-ray fluorescence (xrf) method to determine their chemical co...
Morphotectonic investigations were carried out by the use of morphometric indices which serve as a tool of identification in regions with active tectonic warp. Landforms in active deformation area are produced from relations of tectonic and surficial processes. One of the most significant landforms underground is rivers that are extremely responsive to tectonic movements mainly uplift and tilti...
Abstract. Understanding the long-term evolution of Earth's plate–mantle system is reliant on absolute plate motion models in a mantle reference frame, but such are both difficult to construct and controversial. We present tectonic-rules-based optimization approach model frame covering last billion years use it as constraint for flow models. Our results net lithospheric rotation consistently bel...
Islamic architecture of Iran has passed one of the most prosperous periods in (10-13AH) centuries and the share of the geographical area of capital of Iran in most part of this period, that's means the city of Isfahan, for many reasons in this glow has been very important. Although about this growth and prosperity and begin and end and its causes there is a difference of opinion, few people hav...
[1] We show evidence of very recent ( 25–40 Myr) geologic activity on the eastern flank of Olympus Mons volcano that includes a suite of fluvial (channel networks), volcanic (emplacement of lava flows and dikes), and tectonic (wrinkle ridges and troughs) processes. The combination and youth of these features confirms the importance of geological activity continuing to the present on Mars. Citat...
Arc continent collision is one of the most fundamental tectonic processes for the formation of new land, and the preservation on land of fragments of oceanic lithosphere (ophiolites). However, the tectonic evolution of arc continent collision is commonly over-simplified in everything from introductory textbooks to complex tectonic models. Major unresolved issues include the response of the fore...
Topographically complex regions on land and in the oceans feature hotspots of biodiversity that reflect geological influences on ecological and evolutionary processes. Over geologic time, topographic diversity gradients wax and wane over millions of years, tracking tectonic or climatic history. Topographic diversity gradients from the present day and the past can result from the generation of s...
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