who is sal masekela dating - Sm nd dating garnet

Due to these characteristics, the two elements are relatively stationary through planetary evolution and are thought to retain isotopic abundance characteristics of primitive planetary material, i.e. The experimental result indicate that the eclogites were formed from ocean-island basalt with contamination from sediments to produce the intermediate ɛHf values.

The chondritic uniform reservoir model age is the age at which the material, from which rock and mineral forms, leaves the chondritic uniform reservoir, i.e.

sm nd dating garnet-86

Sm nd dating garnet dating knox de luxe hats

We have micro-sampled the garnet crystals over specific radial dimensions, and measured the Nd isotopes of these small sample masses, as Nd O via solid source mass spectrometry, to determine the Sm-Nd age difference between the core and bulk crystals.

Using a peak metamorphic P-T condition of 8±1 kbar, 820±30°C [Spear and Parrish, J. 37 (1996) 733-765], the core (67.3±2.3 Ma) and bulk (60.9±2.1 Ma) ages of the British Columbian garnet sample yield a cooling rate of 2-13°C/Myr, which is in very good agreement with the cooling rates that we have derived by modeling the retrograde Fe-Mg zoning in the same garnet, and assuming the same peak metamorphic P-T condition.

36 (2001) 167-175] recently presented a method of determining the cooling rates of rocks from the difference between the core and bulk ages of a crystal, as determined by a single decay system.

The samples belong to the metamorphic core complex, Valhalla, British Columbia, and the mid-crustal magmatic arc exposure of the Salinian terrane, California.

AAr age for this hornblende indicates cooling through ˜525°C at 119±2 Ma.

In a nearby amphibolite, garnets with a two-stage growth history consist of inclusion-rich cores surrounded by discontinuous, inclusion-free overgrowths.

Due to chemical properties of the two elements, namely their valences and ionic radii, Lu is usually found in trace amount in rare-earth element loving minerals, such as garnet and phosphates, while Hf is usually found in trace amount in zirconium-rich minerals, such as zircon, baddeleyite and zirkelite.

With the use of inductively coupled plasma mass spectrometry (ICP–MS) with multi-collector (also known as MC–ICP–MS) in later years, the dating method is made applicable to date diverse earth materials.

Considering earlier cooling rate data derived from closure temperature vs.

age relation of multiple geochronological systems [Spear and Parrish, J. 37 (1996) 733-765], a cooling rate of ∼15-20°C/Myr seems most reasonable for the Valhalla complex.

Apatite has also promising Lu–Hf information, as apatite has high Lu content relative to Hf content.

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