KORELASI BIOSTRATIGRAFI FORAMINIFERA PLANKTON DAN NANNOPLANKTON TERSIER INDONESIA BAGIAN TIMUR (Studi Kasus: Pulau Sumba) - Isnaniawardhani, Vijaya; Abdullah, Chalid Ilham; Pratiwi, Santi Dwi (Fakultas Teknik Geologi Universitas Padjadjaran, 2021)
ABSTRAKStudi korelasi biostratigrafi Tersier dilakukan di Pulau Sumba yang tersusun oleh batuan sedimen klastik hasil pengendapan di lingkungan laut dalam. Foraminifera plankton dan nannoplankton dijumpai melimpah pada singkapan-singkapan batuan yang secara stratigrafi bisa ditelusuri kemenerusannya. Zonasi biostratigrafi foraminifera plankton dan korelasinya dengan zonasi biostratigrafi nannoplankton ditentukan berdasarkan batas pemunculan dan kepunahan spesies indeks. Tatanan biostratigrafi foraminifera plankton Pulau Sumba dapat dikelompokkan menjadi 12 zona, yang berurutan dari tua ke muda sebagai berikut: (1) zona selang Globigerina tripartita - Globorotalia centralis, (2) zona kisaran Globorotalia mexicana, (3) zona kisaran Globorotalia centralis, (4) zona kisaran Globigerina tapuriensis, (5) zona kisaran Globigerina ampliapertura, (6) zona kisaran Globigerinoides quadrilobatus altiaperturus, (7) zona kisaran Praeorbulina glomerosa curva, (8) zona kisaran Sphaeroidinella subdehiscens, (9) zona selang Globorotalia acostaensis – Globorotalia plesiotumida, (10) zona selang Globorotalia plesiotumida - Globorotalia tumida, (11) zona selang Globorotalia tumida - Sphaeroidinella dehiscens, dan (12) zona kisaran Sphaeroidinella dehiscens. Tatanan biostratigrafi nannoplankton Pulau Sumba dapat dibedakan menjadi 11 zona, yaitu: (1) zona kisaran Discoaster tani nodifer, (2) zona selang Chiasmolithus oamaruensisSphenolithus pseudoradians, (3) zona selang Sphenolithus pseudoradians – Sphenolithus distentus, (4) zona selang Sphenolithus distentus – Discoaster druggi, (5) zona selang Discoaster druggi - Helicosphaera ampliapertura, (6) zona selang Helicosphaera ampliapertura - Sphenolithus heteromorphus, (7) zona kisaran Discoaster hamatus, (8) zona selang Discoaster hamatus – Discoaster quinqueramus, (9) zona kisaran Discoaster quinqueramus, (10) zona selang Discoaster quinqueramus - Discoaster asymmetricus, dan (11) zona kisaran Discoaster asymmetricus. Korelasi biostratigrafi berdasarkan foraminifera plankton dan nannoplankton pada urutan batuan Paleogen yang umumnya tersingkap di Sumba Barat; maupun Neogen yang tersingkap di Sumba Barat dan Timur menunjukkan resolusi yang baik dalam penentuan umur.Kata Kunci:biostratigrafi, foraminifera plankton, sumba barat, paleogen, penentuan umur.ABSTRACTTertiary biostratigraphy correlation studies were carried out on Sumba Island which is composed of clastic sedimentary rocks deposited in the deep-sea environment. Plankton foraminifera and nannoplankton are abundantly found in rock outcrops which can be traced stratigraphically. The plankton foraminifera biostratigraphy zonation and its correlation with the nannoplankton biostratigraphy zonation was determined based on the occurrence and extinct of index species. The plankton foraminifera succession on Sumba Island can be grouped into 12 zones, from old to young as follows: (1) Globigerina tripartita - Globorotalia centralis interval zone, (2) Globorotalia mexicana range zone, (3) Globorotalia centralis range zone, (4) ) Globigerina tapuriensis range zone, (5) Globigerina ampliapertura range zone, (6) Globigerinoides quadrilobatus altiaperturus range zone, (7) Praeorbulina glomerosa curva range zone, (8) Sphaeroidinella subdehiscens range zone, (9) Globorotalia acostaensis - Globorotalia plesiotumida interval zone, (10) Globorotalia plesiotumida - Globorotalia tumida interval zone, (11) Globorotalia tumida - Sphaeroidinella dehiscens interval zone, and (12) Sphaeroidinella dehiscens range zone. The nannoplankton biostratigraphic succession on Sumba Island can be divided into 11 zones, namely: (1) Discoaster tani nodifer range zone, (2) Chiasmolithus oamaruensis - Sphenolithus pseudoradians interval zone, (3) Sphenolithus pseudoradians - Sphenolithus distentus interval zone, (4) Sphenolithus distentus - Discoaster druggi interval zone, (5) Discoaster druggi - Helicosphaera ampliapertura interval zone, (6) Helicosphaera ampliapertura - Sphenolithus heteromorphus interval zone, (9) Discoaster hamatus range zone, (8) Discoaster hamatus - Discoaster quinqueramus interval zone, (9) Discoaster quinqueramus range zone, (10) Discoaster quinqueramus - Discoaster asymmetricus interval zone, and (11) Discoaster asymmetricus range zone. Biostratigraphic correlation based on foraminifera plankton and nannoplankton in Paleogene rock sequences which are generally exposed in West Sumba; and Neogene exposed in West and East Sumba show a good resolution in age determination.Keyword: biostratigraphy, plankton foraminifera, west sumba, paleogen, age determination.