ANALISIS TENSOR FASE DAN PEMODELAN 2D DATA MAGNETOTELURIK GABBS VALLEY, NEVADA, USA

Pahri Pahri, Andri Yadi Paembonan, Selvi Misnia Irawati

Abstract


Metode magnetotellurik (MT) merupakan salah satu teknik dalam metode geofisika yang menggunakan sumber alami dalam bentuk medan elektromagnetik yang berasal dari medan listrik dan variasi medan magnet di bumi. Dalam proses interpretasi kondisi bawah permukaan bumi, data MT masih dipengaruhi oleh noise atau distorsi yang akan menutupi dimensionalitas sebenarnya. Oleh karena itu dilakukan analisis tensor fase untuk menentukan dimensionalitas dan arah geoelectrical strike guna mengidentifikasi struktur bawah permukaan yang tidak dipengaruhi oleh distorsi galvanic. Berdasarkan hasil yang diperoleh, daerah penelitian memiliki dimensionalitas 2D dengan orientasi barat laut – tenggara dengan arah N345 E. Hasil inversi 2D menunjukkan bahwa nilai resistivitas < 10  diidentifikasi sebagai zona alterasi atau clay cap yang didominasi oleh mineral smektit. Nilai resistivitas 20 – 250  diidentifikasi sebagai reservoar yang bersifat permeabel yang tersusun atas batu pasir kasar, kerikil, basal, andesit, riolit, riodasit tuff dan konglomerat. Lapisan dengan nilai resistivitas > 250  diidentifikasi sebagai Upper Triassic Metasediment yang mengalami sedimentasi yang sangat keras, hal tersebut disebabkan tekanan dan suhu tinggi. Lapisan ini tersusun atas meta batu lanau, batu lempung, meta batu pasir, dan meta konglomerat.

Keywords


2D Inversion; Geothermal Exploration; Magnetotelluric; Phase Tensor

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References


Booker, J.R. (2013). The Magnetotelluric Phase Tensor: A Critical Review. Surveys in Geophysics, 35, 7-40.

Caldwell, T. G., Bibby, H. M., & Brown, C. (2004). The magnetotelluric phase tensor. Geophysical Journal International, Vol. 158, 457-469.

Castells, A. M. (2006). A Magnetotelluric Investigation of Geoelectrical Dimensionality and Study of the Central Betic Crustal Structure. Barcelona: Universitat de Barcelona Departament de Geodinamica i Geofisica.

Earney, T., Schermerhorn, W., Peacock, J., Glen, J.M.G., Craig, J., Faulds, J.E., & Siler, D.L. (2020). Integrating High Resolution Gravity, Magnetic and Magnetotelluric Data to Characterize the Structural Framework of a Blind Geothermal System in Southern Gabbs Valley, NV. American Geophysical Union.

Faulds, J.E., Craig, J.W., Hinz, N.H., Coolbaugh, M.F., Glen, J.M., Earney, T.E., Schermerhorn, W.D., Peacock, J., Deoreo, S.B., & Siler, D.L. (2018). Discovery of a Blind Geothermal System in Southern Gabbs Valley, Western Nevada, through Application of the Play Fairway Analysis at Multiple Scales. GRC Transactions, v 42.

Febrika, G., Setyawan, A., Nurwidiyanto, M., & Raharjo, I. (2017). Identifikasi Geoelectrical Strike dan Dimensionalitas berdasarkan Analisis Phase tensor untuk pemodelan Magnetotellurik di lapangan panas bumi YGF. Youngster Physics Journal, 115-122.

Hardini, P., Zaenudin, A., & Handoyo, R. (2013). Penerapan Koreksi Statik Time Domain Elektromagnetik (TDEM) Pada Data Magnetotelurik (MT) Untuk Pemodelan Resistivitas Lapangan Panasbumi “SS”. JGE (Jurnal Geofisika Eksplorasi), 01(02).

Irawati, S.M., Hidayat, & Grandis, H. (2019). Magnetotelluric (MT) Data Analysis and 2D Modeling of the Kutai Basin, Indonesia: Preliminary Result. EAGE Earthdoc, 1102-1148.https://doi.org/10.3997/22144609.201900406.

Irawati, S.M., Hidayat, Wijanarko, E., & Grandis, H. (2022). Integrated Magnetotelluric (MT), Gravity and Seismic Study of Lower Kutai Basin Configuration. Journal of Engineering and Technological Sciences, 54, 220103. https://doi.org/10.5614/j.eng.technol.sci.2022.54.1.3.

Jason, W., Craig, J. E., Faulds, N. H., Hinz, T. E., Earney, W. D., Schermerhorn, D. L., & Deoreo, S. B. (2021). Discovery and Analysis of a Blind Geothermal System in Southeastern Gabbs Valley, Western Nevada, USA. Great Basin Center for Geothermal Energy, 1-46.

Muntean, J., Davis, D., & Ayling, B. (2017). The Nevada mineral industry 2016, Nevada Bureau of Mines and Geology Special Publication MI-2016. Nevada: Nevada Bureau of Mines and Geology.

Niasari, S.W. (2016). A Short Introduction to Geological Strike and Geoelectrical Strike. AIP Conf. Proc. 1755, 100002.

Peacock, J. R., & Siler, D. L. (2021). Bottom-up and Top-Down Control on Hydrothermal Resources in The Great Basin: An Example from Gabbs Valley, Nevada. Geophysical Research Letters, 48.

Pranata, E., Irawati, S.M., & Niasari, S.W. (2017). Magnetotelluric Data Analysis using Swift Skew, Bahr Skew, Polar Diagram, and Phase Tensor: A Case Study in Yellowstone, US. A Physical and Computational Sciences, 54(3), 311-317.

Rodi, W. L. & Mackie. (2001). Nonlinear Conjugate Gradients Algorithm for 2-D Magnetotelluric Inversion. Geophysics, 174-187.

Simpson, F., & Bahr, K. (2005). Practical Magnetolellurics. Cambridge University Press.

Tait, E. E., Schermerhorn, W. D., Glen, J. M., Peacock, J., Craig, J. W., Faulds, J. E., Nicholas, H.H., & Siler, D. (2018). Geophysical Investigations of a Blind Geothermal System in Southern Gabbs Valley, Nevada. GRC Transactions, Vol. 42.

Vozoff, K. (1991). The Magnetotellurik Method in Electromagnetic Methods. Applied Geophysics, Vol. 2 Aplication, M.N. Nabighian (ed), SEG Publishing.

Yogasatria, G. & Grandis, H. (2018). Analysis of Geoelectric Strike Direction of Magnetotelluric Data from A Geothermal Area, 2nd South-East Asian Conference on Geophysics (SEACG), Denpasar, Bali – Indonesia, 7-10 Agustus 2018.




DOI: https://doi.org/10.23960/jge.v9i3.301

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