Radiometric dating oldest rock


04-Feb-2017 18:43

Next, a major collision took place, triggering the late (Ottawan) phase of the Grenvillian orogeny; the rocks were deformed, deeply buried, and underwent high-grade (granulite-facies) metamorphism.In post-Grenville time (after ~ 900 Ma), the crust in the NYC area consisted of the compositionally varied, medium- to coarse-grained rocks now known collectively as the Fordham Gneiss 400 million years, the ancient supercontinent (formed by Grenvillian collisions) began to split up (Figure 4A).Although the Ned Mountain formation was originally defined on the basis of its stratigraphic relationships and its particular lithologic characteristics, we have been testing our interpretation by whole-rock chemical analyses and zircon age determinations.We have found that all the components of the Ned Mountain formation are linked together by the special suite of mafic rocks (amphibolites) that they contain; these amphibolites have many chemical characteristics in common, which serve to distinguish them from the Fordham Gneiss and from most other rock units in the region.We have informally named this stratigraphic unit the Ned Mountain formation.The Ned Mountain formation is lithologically varied, and is divided into several members, illustrated on Figure 3.We interpret the Ned Mountain formation and Manhattan Schist as age-equivalent, correlative units, and infer that the Manhattan Schist Amphibolite composition has also help untangle confusion regarding the Hartland formation.

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Here, we provide a brief outline of the geologic history of the region, which is also summarized on Table 1, Simplified Geologic History of the New York City Area.

Bimodal (mafic felsic) igneous rock suites like the Yonkers/amphibolite association are characteristic of continental rift zones.



The processes change a pre-existing igneous or sedimentary rock into a the oldest layersare at the This document discusses the way radiometric dating and… continue reading »


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Uranium–lead dating, abbreviated U–Pb dating, is one of the oldest and most refined of the radiometric dating schemes. It can be used to date rocks that formed and crystallised from about 1 million years to over 4.5 billion years ago with routine precisions in the 0.1–1 percent range. The dating method is usually performed on the mineral… continue reading »


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Go to for a free trial and use the offer code SCISHOW tosupport this channel and save 10% off your first purchase of a website or domain.… continue reading »


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Radiometric dating is used to The oldest rocks on Earth, radioactive dating What IsRadioactive Dating, and How Does It Work? Rock Deformation and… continue reading »


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