Karakteristik Geokimia Basalt Busur Gunungapi Tholeitik Formasi Manamas di Sungai Metan, Baun, Timor

Angga Jati Widiatama, Lauti Dwita Santy, Joko Wahyudiono, Sari Widyastuti, Lia Fitria Rahmatillah

Abstract


Lava basalt berstruktur bantal tersingkap di Sungai Metan, Baun, Timor, yang termasuk dalam anggota batuan gunung api Formasi Manamas. Penelitian geokimia batuan dilakukan menggunakan metode analisis XRF dan ICP-MS menunjukkan basalt memiliki karakteristik basalt subalkalin, bersifat tholeitik yang terbentuk pada busur gunungapi tholeitik akibat penunjaman Lempeng Samudera Hindia di bawah Busur Banda yang berumur Miosen-Pliosen. Basalt subalkali di Sungai Metan menunjukkan pengayaan unsur logam dan unsur large ion lithophile (LILE) yang dipengaruhi fluida, ditunjukkan oleh adanya hubungan positif antar unsur logam jejak mudah bergerak. Pengayaan yang dipengaruhi oleh fluida ditafsirkan sebagai produk akibat meleburnya lempeng samudera yang menunjam di bawah busur gunung api.


Katakunci: Basalt, busur tholeitik, Sungai Metan, Formasi Manamas, Timor.


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DOI: http://dx.doi.org/10.33332/jgsm.geologi.v21i3.449

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