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Research Paper | Geology | Indonesia | Volume 3 Issue 4, April 2014 | Popularity: 6.4 / 10

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The Lithological Succession in East Kutai Basin, East Kalimantan, Indonesia: Revisited in a New Data On Litho-Biostratigraphic

Sunardi.E, Isnaniawardhani.V, Cibaj.I, Amiruddin, Haryanto.I

Abstract: Discontinuous of lithological successive in the Kutai Basin was controlled by stratigraphic framework and geological structures. Integrated detail surficial mapping and laboratory analyses, supported by remote sensing interpretation, led to compile the lithological succession based on recent lithostratigraphy and biostratigraphy data. Serpentinite and deep marine turbiditic metasediment basement are the oldest exposure rocks in study area. Tertiary rocks was situated unconformably on basement with tectonic boundaries. Interval A (eq. Kuaro Formation) comprise beach pebbly sandstone overlain by repeated channel sandstone, shale/silt and coal beds. Lepidocyclina limestone of Interval B (eq. Pamaluan Formation) represents carbonate build ups on a shelf in inner to outer neritic zone since Early Miocene (Te zone, N.5 to N.7 or NN.2 to NN.4 zone). They are overlain by turbiditic carbonate layers and conglomeratic sand in a continental slope, channel and leeve. Six siliciclastic prograding shallow marine of Interval C (eq. Bebulu Formation) unconformably rest on older rocks. The coarsening up carbonaceous shale/silt overlain by sandstone refected strom activities was deposited in shoreface in Middle Mocene (N.7-N.8 or NN.4 to NN.5), capped by outer shelf break transgressive carbonate build up (Tf.1-2 zones). A platform limestone were recorded on the top of this interval. Interval D (eq. Pulau Balang Formation) is composed of a number sequences reflecting fluvial, delta and shalow marine depositional environments. Thirty prograding sequences are observed in this interval that characterized by progressively shallower facies, such as fluviatile flood plain carbonaceous shale and silt covered by channel sandstone; prodelta shale/siltstone by deltaplain shale and coal beds. At Interval E (eq. Balikpapan Formation), several fluviatil retrograding sequences indicated by repeating fining upward channel sandstone, flood plain shale/mudstone and marsh coal beds during latest Middle to Late Miocene in supratidal and intertidal zone with brackish influence. A series of deltaic sequences, prodelta shales and coal beds, as well sandstone delta front, presented in various levels during Middle-Late Miocene at upper section (Interval F eq. Kampung Baru Formation). Pre-Tertiary basement and Tertiary rocks in East Kutai Basin were generated by structural geology in NW-SE and NE-SW directions; besides N-S minor trend. Tectonic activities controlled the successions concerning with lateral and vertical lithologic distributions.

Keywords: East Kutai Basin, prograding, lithologic succession, delta, lithostratigraphy, biostratigraphy

Edition: Volume 3 Issue 4, April 2014

Pages: 707 - 713

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