Permasalahan geollogi gunungapi di Indonesia

S. Bronto, .. and Ev. Budiadi, .. and Hill Gendoet Hartono, . (2004) Permasalahan geollogi gunungapi di Indonesia. Majalah Geologi Indonesia, 19 (2): 3. pp. 91-105. ISSN 0216-1061

Text (Jurnal) 2_Permasalahan Geologi Gunungapi di Indonesia.pdf - Published Version Download (11MB)

Abstract

Penelitian geologi sejak tiga dasa warsa ini agak condong kepada arti sempitstratigra i sehingga kurang mengembangkan arti luas stratigrafi sebagai ilmu yang membahas aturan, hubungan dan kejadian macam-macam batuan di alam dalam ruang dan waktu. Hal ini sangat terasa setelah menghadapi permasalahan geologi di daerah batuan gtinungapi termasfJk batuan terobosan berumur Terrier atau lebih tua. Berlandaskan pemahaman geologi sedimenter, kebanyakan ahli geologi memandang batuan gunungapi sebagai batuan sedimen, setelah mengendap kemudian diterobos oleh magma yang membentuk batuan beku terobosan. Secara volkanologi, berdasarkan prinsip the present is the key to the past, batuan gunungapi dan batuan tembosan tersebut merupakan hasil satu kesatuan proses volkanisme yang kejadiannya dalam waktu relatifbersamaan, sebagai bahan ekstrusiva dan intrusiva. Sebagai salah satu bahan ekstrusiva, endapan turbidit gunungapi dapat terbentuk langsung dari erupsi dan diendapkan pada lereng atau kaki gunungapi. SelanjfJtnya, dengan prinsip horisontalitas, para ahli geologi juga beranggapan bahwa perlapisan batuan gunungapi yang miring dinyatakan sudah terpengaruh oleh kegiatan tektonika. Dari sudut pandang volkanologi, perlapisan miring batuan gunungapi itu dapat merupakan kemiringan asli pada tubuh gunungapi. Bahkan, struktur sesar berpola memancar dan konsentris, serta lipatan berpola memusat dapat juga disebabkan oleh kegiatan gunungapi. Untuk menjawab permasalahan geologi gunungapi tersebut maka pemahaman terhadap genesa batuan gunungapi perlu tems dikembangkan, yang mencakup penentuan sumber erupsi, mekanisme pembekuan/pengendapan, lingkungan pengendapan dan umur. Dalam rangka menentukan pusat erupsi dan merekonstniksi bentuk tubuh serta sebaran gunungapi Tersier dilakukan pendekatan secara geomarfologi, sedimentologi, struktur geologi, stratigrafi, petrologi, geokimia dan pentarikhan secara radiometri.

Kata kunci. geologi, gunungapi, Indonesia.

ABSTRACT

So far, geologists seem to point out on the sensu stricto meaning ofstratigraphy causing the understanding ofits broader meaning that deals with arrangement, relationship and the origin ofrocks in nature, is less developed. This has been realized especially in conjunction with geological problems in volcanic rocks including sub volcanic intrusions that have Tertiary or older ages. Based on sedimentary geology, most geologists have considered volcanic rocks as sedimentary nicks which after deposition they were intruded by magma to form intrusive igneous rocks. Following a principal geology, the present is the key to the past, volcanologists are convinced the formation of volcanic rocks and intrusive rocks nearby is in a single proce3s, namely volcanism. Those rocks were formed relatively in the same time as extensive and intmsive material. One of extensive material, i.e. volcanic turbidites, may be generated directly by a volcanic eruption and then were deposited on volcanic slope and surrounding areas. Beginning with a principal of horizontality, among geologists also believe that dipping of volcanic rock layers has been ajf’ected by tectonics. From volcanological point of view, those dipping rocks could be original dips in a volcanic body. Moreover, radier and concentric fault3 ORd concentric pattern offolds can be derived by volcanism. These volcanic geological problems urgently require to develop the understanding of genesis and relationship of volcanic rocks. In order to /Oct2/ire Tertiary volcanic eruption centres, it is suggested to approach by analizing geomorphology, sedimentology, geologic structure, stratigraphy, petrology, geochemistry and radiometric dating.

Keywords.’ geology, volcano, Indonesia.

Item Type:	Article
Uncontrolled Keywords:	geologi, gunungapi, Indonesia geology, volcano, Indonesia
Subjects:	Q Science > QE Geology
Depositing User:	suma SR romdani
Date Deposited:	12 Dec 2020 05:31
Last Modified:	12 Dec 2020 05:31
URI:	https://repository.itny.ac.id/id/eprint/2590

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