Local zonation of foraminifera in the North West Java Basin

Abstrac
Role of analysis foraminifera in North West Java Basin is importance because it can be determine age and depositional environment very well. This research observes foraminifers’ that emerging at the age Miocene in North West Java Basin. Research data is result of biostratigraphic analysis from 6 chosen well representing some fields oil and gas property of XXXXX which ahead done by group of Stratigraphy PPPTMGB "LEMIGAS" through service. The purpose is analyze and makes local of zonation foraminiferal that later earns as reference at the time of determination of zonation or age other well in North West Java Basin.

The age Miocene of planktonic foraminifers is enough abundance especially in the Upper Cibulakan and Parigi Formation, but unable to grow in the Talangakar and Baturaja Formation. The growth of bentonic foraminifers is good enough started from Talang Akar until Parigi Formation. Based on some literature and calibrated with nannoplankton and palinomorf, the benthonic foraminiferal earn also determine age. This thing based from first or last appearance of larger and smaller benthonic foraminiferal. The marker species of planktonic foraminifers are composed of Globorotalia tumida, Globorotalia merotumida, Globorotalia plesiotumida, Globorotalia acostansis, Globorotalia siakensis, Orbulina universa, Globigerinoides subquadratus, Globorotalia fohsi robusta, Globorotalia fohsi fohsi, Globigerinoides bisphaericus and Globigerinoides diminutus. The larger benthonic foraminiferal species is Lepidocyclina (T) orientalis, Borelis melo, Lepidocyclina (N) inflata, Lepidocyclina (N) tournoueri, Spiroclypeus sp. and Miogypsina sp. The age diagnostic species of the benthonic foraminifera of rotaliid group covers Pseudorotalia catiliformis, Pseudorotalia indopacifica, Pseudorotalia shcroeteriana angusta, Cavarotalia annecten, Asterorotalia yabei and Ammonia umbonata.

Result of this research is the form of 3 column of local zonation foraminiferal Miocene covering planktonic foraminiferal, larger benthonic foraminiferal and smaller benthonic foraminiferal (rotaliid group) zonation. Benthonic foraminiferal zonation only as complement when marker species of planktonic foraminifers unable to grow.