PEMODELAN TIGA DIMENSI(3-D) STRUKTUR GEOLOGI BAWAH PERMUKAAN DAERAH PANAS BUMI TULEHU DI KABUPATEN MALUKU TENGAH MENGGUNAKAN METODE GRAVITASI

KALEB AMAGHI YENUSI, Dr.Ing. ARI SETIAWAN, M.SI

2017 | Tesis | S2 Ilmu Fisika

Daerah panas bumi Tulehu Kabupaten Maluku Tengah memiliki wilayah dengan prospekpanas bumi, dicirikan dengan manifestasi panas bumi berupa mata air panas. Penelitian ini bertujuan untuk mengidentifikasi dan menginterpretasi struktur geologi bawah permukaan daerah panas bumi Tulehu berdasarkan pemodelan tiga dimensi (3-D) menggunakan data gravitasi. Struktur geologi bawah permukaan yang akan diidentifikasi berupa sesar dan intursi batuan beku. Anomali Bouguer lengkap diproyeksikan ke bidang datar.Anomali regional dan residual dipisahkan dengan menggunakan kontinuasi ke atas.Tahap selajutnya menggunakan pemodelan 3-D berdasarkan analisis data hasil kontinuasi keatas yang merupakan anomali Bouguer residual. Anomali residual yang digunakan adalah pada pengangkatan 1000 meter dari permukaan laut. Pemodelan 3-D menggunakan perangkat lunak grablox dan bloxer. Hasil pemodelan menunjukkan adanya patahan berarah Baratdaya-Timur laut daerah panas bumi Tulehu. Hasil pemodelan juga menunjukkan adanya intrusi batuan beku dibagian Baratdaya daerah penelitian. Daerah patahan diindikasikan oleh adanya perbedaan densitas dengan daerah sekitarnya (Breksi Andesit). Zona intrusi (nilai densitas 2,9 gr/cm3 � 3,0 gr/cm3) diinterpretasikan sebagai batuan Lava Andesit.

Tulehu geothermal field of Central Maluku has an area with geothermal prospects, characterized by geothermal manifestations(i.e. hot springs). This research aimed to identify thesubsurface geological structure of the Tulehu area based on three dimension (3-D) modeling using gravity data. Subsurface geological structures wich to be identified were fault and igneous rock intrusion. The complete Bouguer anomaly was projected into the flat plane. Regional and residual anomalies were separated by using upward continuation. The next stage used 3-D modeling based on data analysis of upward continuity result, which was Bouguer residual anomaly. Residual anomalies were used on upward of 1000 meters from sea level. 3-D modeling used grablox and bloxer software. The modeling results indicate faults in the direction of Southwest � Northeast in the geothermal area of Tulehu. Modeling results to indicate igneous rock intrusion in the direction of Southwest research area. The faultswere indicated by the difference of density with surrounding area (i.e. Andesite Breccia). The Intrusion zone (i.e. 2,9 gr/cm3 � 3,0 gr/cm3) was interpreted as Andestic Lava rocks.Tulehu geothermal field of Central Maluku has an area with geothermal prospects, characterized by geothermal manifestations(i.e. hot springs). This research aimed to identify thesubsurface geological structure of the Tulehu area based on three dimension (3-D) modeling using gravity data. Subsurface geological structures wich to be identified were fault and igneous rock intrusion. The complete Bouguer anomaly was projected into the flat plane. Regional and residual anomalies were separated by using upward continuation. The next stage used 3-D modeling based on data analysis of upward continuity result, which was Bouguer residual anomaly. Residual anomalies were used on upward of 1000 meters from sea level. 3-D modeling used grablox and bloxer software. The modeling results indicate faults in the direction of Southwest � Northeast in the geothermal area of Tulehu. Modeling results to indicate igneous rock intrusion in the direction of Southwest research area. The faultswere indicated by the difference of density with surrounding area (i.e. Andesite Breccia). The Intrusion zone (i.e. 2,9 gr/cm3 � 3,0 gr/cm3) was interpreted as Andestic Lava rocks.

Kata Kunci : Pemodelan 3-D, Panas Bumi, Metode Gravitasi