# The Geology of Indonesia

The Geology of Indonesia Wikibook is an online book about the Geology of Indonesia. This is a Wikibooks project, aimed for a collaborative approach to gather maximum knowledge available about the subject. It is intended to compile the current technical knowledge on the geology of Indonesia. Anybody is welcome to contribute to this book.
The initial content of this Wikibook came from "An Outline of the Geology of Indonesia", Darman, H. & Sidi, H. (eds.), 2000, a special publication of the Indonesian Association of Geologist (IAGI). Different authors have contributed to this book and new information is added through time.
As Indonesia is a vast region, the general geology for each region is described separately under different chapters. The book also covers the geological application for the petroleum, natural resources and geological hazards. The geological hazard will also cover the recent development of earthquake, tsunami, and other hazards in Indonesia. Indonesia is located on the Pacific Ring of Fire with extensive volcanic network which give rise to the recent earthquake.

## Preface

Indonesia is the largest archipelagic state in the world comprising five major islands and about 300 smaller island groups. Altogether there are 13,667 islands and islets of which about 6,000 inhabited. The archipelago is situated on a crossroad between two oceans, the Pacific and Indian oceans, and bridges two continents, the Asian and Australian. Indonesia has a total area of 9,8 million km$^2$, of which more than 7,9 million km$^2$ are under water. Physiographically, the islands of Sumatra, Java and Kalimantan are attached to the Sunda Shelf of the Asian continent. On this landmass the water depth does not exceed 200 meters. To the east, Irian Jaya and the Aru islands lie on the Sahul Shelf, which are parts of the Australian continent. Located between these two shelves is the island group of Nusa Tenggara, Sulawesi, Maluku and Halmahera. These islands are encircled by deep seas which in many places reach 5,000 meters.
About 60 Tertiary sedimentary basins, spread out from Sumatra in the west to Irian Jaya in the east, are identified in Indonesia. So far only 38 basins have been explored and drilled for petroleum and 14 of the are now producing oil and gas. Seventy three percent of these basins are located offshore, about one third of them in the deeper sea, with water depth exceeding 200 m.
Background
In 1949, R. W van Bemmelen published a compilation of reports and data on the Geology of Indonesia. The book was reprinted in 1970 with no additional data. This book has documented a lot of data and geological understanding before the second world war and only covered onshore geology of Indonesia. W. Hamilton published a book titled Tectonics of the Indonesian Region in 1979 which include offshore seismic data and remote sensing. The Indonesian geologist celebrated the 50th anniversary of R. W. van Bemmelen's book in a conference titled "Tectonics and Sedimentation of Indonesian" in 1999 and published "An Outline of the Geology of Indonesia" the following year (2000). The data and the knowledge on the geology of Indonesia are so much and make it so difficult to compile them in a single book. In 2007 the Wikibook of the Geology of Indonesia was started by converting Än Outline of the Geoloyg of Indonesia"to a digital version. The idea is to include as many geoscientists as possible to keep the information on the geology of Indonesia as good as possible. This online version of the Geology of Indonesia will also give a chance to renew or update the information stored at anytime.
* Contributors
* Data Source

## 1. Introduction

Indonesia is the largest archipelagic state in the world comprising five major islands and about 300 smaller island groups. Altogether there are 13,667 islands and islets of which about 6,000 are inhabited. The archipelago is situated on a crossroad between two oceans, the Pacific and Indian oceans, and bridges two continents, the Asian and Australian. Indonesia has a total area of 9.8 million km$^2$, of which more than 7.9 million km$^2$ are under water. Physiographically, the islands of Sumatra, Java and Kalimantan are attached to the Sunda Shelf of the Asian continent. On this landmass the water depth does not exceed 200 meters. To the east, Irian Jaya and the Aru islands lie on the Sahul Shelf, which are parts of the Australian continent. Located between these two shelves is the island group of Nusa Tenggara, Sulawesi, Maluku and Halmahera. These islands are encircled by deep seas which in many places reach 5,000 meters. About 60 Tertiary sedimentary basins, spread out from Sumatra in the west to Irian Jaya in the east, are identified in Indonesia. So far only 38 basins have been explored and drilled for petroleum and 14 of them are now producing oil and gas. 73 percent of these basins are located offshore, about one third of them in the deeper sea, with water depth exceeding 200 m.
* History of geological studies

## 2. Tectonic

* Regional Tectonic Framework
* Plate Tectonic
* Major Suture

## 3. Stratigraphy

The stratigraphical knowledge of the Indonesian Archipelago will be summarized in this chapter. A synopsis of the stratigraphy of the Netherlands East Indies has been published by BROUWER (1925) and L. M. R. RUTTEN (1927). In 1938 UMBGROVE gave a comprehensive review of the geological history of the East Indies. A number of important contributions to the stratigraphy which appeared in 1937–1938, not available to UMBGROVE, were summarized by SMIT SIBINGA (1940). L. M. R. RUTTEN (1948) and DE BEAUFORT (1948) reviewed the paleontological work carried out in the Netherlands for the Dutch Overseas Territories during the period 1918–1943.
Other important reviews on the stratigraphy of the Indian Archipelago are to be found in: The "MARTIN-Volume" of the "Leidsche Geologische Mededeelingen" (1931), in which a number of authors gives a review of the paleontological and stratigraphical data up to the year 1930; UMBGROVE (1934 b) on theNeogene, and(1935)on thePre-Tertiary; BADINGS (1936) on the Paleogene; STAUFFER (1945) on the stratigraphy of Indonesia; SMITH (1924, 1925) on the stratigraphy of the Philippines; MONTGOMERY, OSBORN and GLAESSNER on the stratigraphy of Eastern New Guinea 1); CHHIBBER (1934) on the stratigraphy of the Andamans and Nicobars.
In 1950, P. Marks, published Stratigraphic Lexicon of Indonesia, which is a compilation of formation names in Indonesia. The formation names are sorted in alphabetical order with their description, rough map of the localities, and summarized them in stratigraphic charts.
The first Indonesian Stratigraphic Nomenclature guide (Sandi Stratigraphy Indonesia) was published in 1973 by Soejono Martodjojo and Djuhaeni. This book was updated in 1996 and published electronically by the Indonesian Geologist Association. The file is available online in SSI-1996. Many publications related to sequence stratigraphy and seismic stratigraphy in Indonesia were published by the Indonesian Petroleum Association (IPA), the Indonesian Geological Association (IAGI)and other professional organizations. A compilation of updated article on biostratigraphy of SE Asia is currently being prepared by the Indonesian Sedimentologists Forum (FOSI), which aim to issue it in 2014. Another key source on the stratigraphy of Indonesia is the Geological Research and Development Centre of Indonesia (GRDC)
In 1979, S. Sartono, from the Institute of Technology, Bandung, published a lecture outline in Indonesian, titled Stratigrafi Indonesia with occurrence maps of the stratigraphic units in Indonesia. This book also provide updates on R. W. van Bemmelen's book.
For the sake of brevity, in this chapter only some notes will be given on recent advances in our knowledge of the pre-tertiary stratigraphy. For the rest the reader is referred to the regional descriptions.
The tertiary and quaternary formations have a much wider distribution than the pre-tertiary rocks. Their stratigraphy is most important in the unraveling of the evolution of the younger mountain systems in this area. Therefore, the stratigraphy of the Tertiary and the Quaternary will be treated at some length in this chapter.
* Basement
* Paleozoic
* Mesozoic
* Cenozoic

## Regional Geology

* Sumatra
* Natuna
* Java & Java Sea
* Kalimantan
* Makassar Strait
* Sulawesi Sea
* Sulawesi
* The lesser Sunda Islands
* Halmahera
* Banda Arc
* Timor
* Arafura Sea
* Papua

## Petroleum Geology

* Sedimentary Basins
* Exploration License
* Petroleum Issues
* Recent Development

## Geological Hazards

* Earthquake
* Volcanoes
* Tsunami
* Landslides

## Geotourism

* Lake Toba
* Ngarai Sianouk
* Krakatau
* Tangkuban Perahu