Geochemistry and Petrogenesis of Pan-african Granitoids in Kaiama, North Central, Nigeria

• 영문명: Geochemistry and Petrogenesis of Pan-african Granitoids in Kaiama, North Central, Nigeria
• 발행기관: 대한자원환경지질학회
• 저자명: Aliyu Ohiani Umaru Olugbenga Okunlola Umaru Adamu Danbatta Olusegun G. Olisa
• 간행물 정보: 『자원환경지질』56권 3호, 259~275쪽, 전체 17쪽
• 주제분류: 자연과학 > 지질학
• 파일형태: PDF
• 발행일자: 2023.06.30

영문 초록

Pan African granitoids of Kaiama is comprised of K-feldspar rich granites, porphyritic granites, and granitic gneiss that are intruded by quartz veins and aplitic veins and dykes which trend NE-SW. In order to establish the geochemical signatures, petrogenesis, and tectonic settings of the lithological units, petrological, petrographical, and geochemical studies was carried out. Petrographic analysis reveals that the granitoids are dominantly composed of quartz, plagioclase feldspar, biotite, and k-feldspar with occasional muscovites, sericite, and opaque minerals that constitute very low proportion. Major, trace, and rare earth elements geochemical data reveal that the rocks have moderate to high silica (SiO2=63-79.7%) and alumina (Al2O3=11.85-16.15) contents that correlate with the abundance of quartz, feldspars, and biotite. The rocks are calc-alkaline, peraluminous (ASI=1.0-<1.2), and S-type granitoids sourced by melting of pre-existing metasedimentary or sedimentary rocks containing Al, Na, and K oxides. They plot dominantly in the WPG and VAG fields suggesting emplacement in a post-collisional tectonic setting. On a multi-element variation diagram, the granitoids show depletion in Ba, K, P, Rb, and Ti while enrichment was observed for Th, U, Nd, Pb and Sm. Their rare-earth elements pattern is characterized by moderate fractionation ((La/Yb)N=0.52-38.24) and pronounced negative Eu-anomaly (Eu/Eu*=0.02-1.22) that points to the preservation of plagioclase from the source magma. Generally, the geochemical features of the granitoids show that they were derived by the partial melting of crustal rocks with some input from greywacke and pelitic materials in a typical post-collisional tectonic setting.

목차

Introduction

Geological Setting

Sampling and Analytical Methods

Results

Discussions

Conclusion

Declaration of Competing Interest

Acknowledgment

References

키워드

granitoids peraluminous tectonic setting petrography partial melting