نتایج جستجو برای: continental crust
تعداد نتایج: 29224 فیلتر نتایج به سال:
The evolution and the growth of the continental crust is inextricably linked to the evolution of Earth's geodynamic processes. The detrital zircon record within the continental crust, as well as the isotopic composition of this crust, indicates that the amount of juvenile felsic material decreased with time and that in geologically recent times, the generation of new crust is balanced by recycl...
Formation of new continental crust in Western British Columbia during transpression and transtension
Crustal growth in the Coast Mountains, along the leading edge of the Canadian Cordillera, was the result of processes associated with horizontal flow of material during transpression and subsequent transtension, and the vertical accretion of mantle derived melts. From 85 to 58 Ma, as exotic terranes were translated northward during transpression, the crust was thickened to about 55 km, and melt...
This paper looks at the challenges confronting plate tectonics— the ruling paradigm in the earth sciences. The classical model of thin lithospheric plates moving over a global asthenosphere is shown to be implausible. Evidence is presented that appears to contradict continental drift, seafloor spreading, and subduction, as well as the claim that the oceanic crust is relatively young. The proble...
Multichannel seismic-reflection data collected on the Peru margin as part of Leg 112 of the Ocean Drilling Program predrilling site survey define some tectonic and sedimentary features of the Lima and Yaquina basins. A narrow accretionary prism is imaged at the toe of the trench slope in both areas. Landward of the accretionary prism is a transition zone that may be underlain by older accreted ...
Rifted continental margins are the product of stretching, thinning and ultimate break-up of a continental plate into smaller fragments, and the rocks lying beneath them store a record of this rifting process. Earth scientists can read this record by careful sampling and with remote geophysical techniques. These experimental studies have been complemented by theoretical analyses of continental e...
When continents break apart, continental crust and lithosphere are thinned until break-up is achieved and an oceanic basin is formed. The most remarkable and least understood structures associated with this process are up to 200 km wide areas of hyper-extended continental crust, which are partitioned between conjugate margins with pronounced asymmetry. Here we show, using high-resolution thermo...
The thermal evolution of crustal exhumation subsequent to the subduction of the continental margin is modeled through numerical solutions to the two-dimensional heat conduction equation. The boundary conditions used in the modeling are basically constrained by available geophysical and geological observations in the Taiwan area. Temperature distributions are calculated at one-million-year inter...
The formation of the Tibetan plateau during the India-Asia collision remains an outstanding issue. Proposed models mostly focus on the different styles of Tibetan crustal deformation, yet these do not readily explain the observed variation of deformation and deep structures along the collisional zone. Here we use three-dimensional numerical models to evaluate the effects of crustal rheology on ...
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