Abstract
In this work, PIXE has been used for a variety of Precambrian proto crustal rocks in the form of granulitic charnockites,Eastern Ghats AP,India.In previous study of exterior part of the charnockite hill elemental analysis using electron microprobe analysis, the elements in host charnockites no Na, traces of Mn,Ca and high Ti,Cl,F (Biotite), no Mn, low Na,and high K,Cl (Hastingsite), and Cl, Fe (Apatite) were only detected, but by using PIXE technique in addition to the above twenty two trace elements are identified. PIXE is highly sensitive and non-destructive method for multi elemental analysis in a variety of Precambrian charnockite rocks down to levels of a few parts per million. The samples chosen for analysis from the central portion of a charnockite hill near Visakhapatnam airport. A big reticular mass of relict litho logical body which is compositionally and physically different from host chatnockite was observed in the central portion of the hill. These experiments are carried out using a 3MV pelletron accelerator facility at the Institute of physics, Bhubaneswar. A collimated proton beam of 2mm diameter is made to fall on to the sample, and the beam current is kept at 20na. A high resolution Si(Li) detector(160ev FWHM at 5.9kev energy) is employed in the present experiments and the Guelph PIXE (GUPIX) software package is used to analyze the spectra. The elements identified in this Precambrian charnockite rock are Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Se, Br, Rb, Sr, Y, Zr, Nb, Mo, Ru, Ag, Pb..From this study these rocks are early crust(proto crust) rocks. These samples are to belong to a very important geological phase and further work on petrography and REE (Rare Earth Elements in Geology)of the rock is indeed to firmly establish its exact parentage.
Highlights
As is well known the earth is conventionally divided into crust, mantle and core
A big lenticular mass of relict lithological body(proto crustal rocks in the form of charnockite) which is compositionally and physically different from the host charnockite was observed in this central portion of the hill
This body is believed to be the caught up body of the early crustal layer.Such samples are rare, Particle Induced X-Ray Emission (PIXE) technique is chosen for the trace elemental analysis [5] of these rare samples as it is a highly sensitive and non destructive method for the simultaneous multi elemental analysis
Summary
As is well known the earth is conventionally divided into crust, mantle and core. The crust is further divided into three major categories continental, transitional and Oceanic. Charnockites are termed as upper mantle basic igneous rocks and are emplaced into proto crustal rocks during Precambrian times In this way the charnockites sometimes may contain the relict bodies of earlier crustalrocks (proto crust). A big lenticular mass of relict lithological body(proto crustal rocks in the form of charnockite) which is compositionally and physically different from the host charnockite was observed in this central portion of the hill This body is believed to be the caught up body of the early crustal layer (possibly proto crust).Such samples are rare, PIXE technique is chosen for the trace elemental analysis [5] of these rare samples as it is a highly sensitive and non destructive method for the simultaneous multi elemental analysis. An application of PIXE technique to Proto Crustal Rocks: Geo chemical evaluation of Granulitic
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