نتایج جستجو برای: continental margin sedimentation
تعداد نتایج: 70724 فیلتر نتایج به سال:
■ Abstract The Cordilleran orogen of western North America is a segment of the Circum-Pacific orogenic belt where subduction of oceanic lithosphere has been underway along a great circle of the globe since breakup of the supercontinent Pangea began in Triassic time. Early stages of Cordilleran evolution involved Neoproterozoic rifting of the supercontinent Rodinia to trigger miogeoclinal sedime...
The Greenland ice sheet (GrIS) advanced onto the continental shelf during the last glacial period. While deglacial records for when the GrIS withdrew onto the modern coastline are relatively abundant, the timing of early GrIS retreat on the shelf is poorly constrained. Here we use planktic foraminiferal d18O, sediment grain size, sedimentation rates, and 14C ages in southeastern Davis Strait co...
Abstract The best exposed Early Miocene (820 m. thick. ) shales and interbedded silty sandstones beds of the Pyawbwe Formation at Sakangyi- Thayat area,Magway Region are investigated geochemically by using Siemens SRS- X Ray 303 AS XRF Spectrometer. Major and some trace element concentrations have been determined to achieve their provenance, tectonic setting ,paleoweathering , paleoclimate and ...
The study of existing cores collected across the Wilkes Land margin provides us with a better understanding of the sediment distribution and processes across this margin during the Holocene, and during Pleistocene glacial and interglacial cycles. Holocene depositional rates are high in deep (>1000m) inner-shelf basins where diatomaceous ooze is deposited at estimated minimum sedimentation rates...
Leg 178 will drill eight sites off the Pacific margin of the Antarctic Peninsula to provide a highresolution record of Antarctic continental climate over the past 6-10 m.y. and a direct check on the presumed glacio-eustatic origin of global sea-level change over the same period. Moreover, it is an essential preliminary to the more difficult task of extracting the complete Cenozoic record of Ant...
Chaldoran area in NW of Iran has Mesozoic oceanic crust basement. The studied rocks of this region can be divided into three groups: ophiolitic gabbros and pillow lavas, ophiolitic volcanoclastics and Eocene lava flows. Ophiolitic mafic rocks show continental volcanic arc natures and Eocene lava flow shows OIB-like nature. During the Mesozoic,the Chaldoran region was situated in the active cont...
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