نتایج جستجو برای: petrography
تعداد نتایج: 1284 فیلتر نتایج به سال:
The geochemical signatures like discordant variation of major and trace elements among felsic-intermediate and basic rocks and mafic enclaves of Malayer region on binary variation plots, decreasing values of FeOt, TiO2, MgO, MnO and CaO accompanied with increasing of SiO2 content from basic to felsic rocks, and decreasing Ni, Cr and Co with increasing SiO2 are considered as indications of mag...
Introduction: Carbonaceous chondrites ALH84051 and ALH84034 rank amongst the most aqueously altered meteorites within the CM group and have been classified as petrologic type 1s. Nearly all primary anhydrous minerals have been replaced by secondary alteration phases, yet these meteorites still possess primitive whole-rock compositions [1,2]. Although elemental transport does not appear to have ...
A thin coating of desert varnish occurs on Forrest 009 and Nurina 004, both equilibrated ordinary chondrite (L6) finds from the Nullarbor Plain, Australia. This finely laminated deposit is chemically and petrographically comparable to the varnish found on terrestrial rocks. Forrest 009, which has a terrestrial age of 5.9 kyr, has a 100-130 μm thick coating of desert varnish that has a laterally...
Introduction: The exploration of the Martian surface by the rovers Spirit, Opportunity, and Curiosity has indicated the widespread presence of clastic rocks of basaltic composition [1-3], many of which have altered to various extents. In this investigation, we have examined basaltic ash and tephra formed through hy-drovolcanism (the explosive interaction of magma with liquid water), glaciovolca...
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