DEEP MARINE BENTHIC FORAMINIFERAL FROM TEMBURONG FORMATION IN LABUAN ISLAND

A paleontological research was conducted in Labuan in pursue of the foraminiferal species of benthic species. Fifteen mudstone samples from Temburong Formation were taken and successfully extracted an amount of benthic foraminifera. The Labuan Island is consists of two major depositional environment; deep-marine and shallowmarine environment, which is highly valuable geologically but the samples were all of Crocker Formation and Temburong Formation to investigate the fossils content of the turbidite sequence. The Temburong Formation comprises of mainly flysch deposit. All of the benthic foraminifers were processed and extracted accordingly using the standard paleontological method with additional method of adding 25ml to 30ml of Hydrogen peroxide. A total of 37 species were found and identified, consist of hyaline and agglutinated group. Thus, the Temburong Formation is considered as deep-sea deposition with the evidence of deep-marine agglutinated foraminifers assemblages ranging from bathyal to abyssal.


INTRODUCTION
The The abundance of foraminifers in most marine sediments is not for a mere reason as they are absolutely useful especially in biostratigraphy correlation.Benthic foraminifer is a good indicator for ancient environment, due to different species will only be able to restrict habits which resulting them to be abundance in specific niche respectively.Thus, these types of foraminifers are widely used to determine a rock ancient depositional environment.The Temburong Formation is initially named and continued by a research researching the formation [1].This formation is characterized by flysch deposits of siltstone and shale repetition.Their argillaceous lithology has common intercalations with slight calcareous pelagic shale [2].Previous researcher concluded that the Temburong Formation is of deep-marine environment by low density turbidity currents [1,3].The last paleontological studies conducted on this formation are by a scientist on planktonic foraminifers concluded that the formation age range from Late Oligocene to late Early Miocene.The aim for conducting this research is to identify the existence of foraminifer's species and its respective depositional environment focusing on benthic foraminifers using standard micropaleontological method.

GENERAL GEOLOGY
Labuan Island consists of four lithological units which are Crocker Formation, Temburong Formation, Setap Shale Formation and Belait Formation [4][5][6][7].A geological map (Figure 1) of the research study area was build based on a study with several modifications [8].The oldest formation is the Crocker Formation followed by the Temburong Formation characterized by a deep-marine deposition [8,1].The Temburong Formation was formed during the deposition of the Oligocene to Upper Miocene along with the West Crocker Formation according to the basin filling of the Tertiary depocentre of North West Sabah Basin [9][10][11].A slight different lithological unit with Crocker Formation which consists of interbedded siltstone and shale, and thick shale unit [12].
Labuan Island was first geologically researched during J. Motley first visit in 1852 on agricultural potential along with lithological and stratigraphy thickness about Kubong Bluff.Another research recorded in a report is on coal deposits by Captain Sir Edward Belcher on his way to H.M.S Semarang.Carl Schmidt did his research on oil and gas occurrence offshore along with the Labuan Exploration Company Limited in 1919 until 1920.A research work on The Geology of the Colony of Borneo was recorded but incomplete until Shell Group restarted that made one of the first geological mapping of Labuan and surrounding areas.
A latest research on Labuan was about foraminiferal occurrence was by a scientist which was focused on the Miocene assemblages which was done in Setap Shale Formation and concluded the blooming of species during Late Early Eocene and said that it was of shallow marine deposition aging Early Miocene.A research on the Temburong Formation done in Tenom and concluded two biozones of foraminiferal which are Globorotalia Zone (P22) and Catapcydrax dissimilis-Praeorbulina sicana Zone (N7) aged Chattian (Late Oligocene) and Burdigalian (Late Early Miocene) respectively.Another research in Labuan Island was on agglutinated foraminifera of Miocene sedimentation.Unfortunately, the Temburong Formation was not directly discussed on the paper.

METHODOLOGY
The research was done with a total of 15 samples of mudstones and shale of Temburong Formation.Preparation of samples was done step by step following based on Armstrong.A crushed sample of shale was prepared in the laboratory by boiling.A quarter of a 500ml of beaker was filled with shale sample and mixed with distilled water for the rest.The mixture was then added a decomposing agent, Sodium Bicarbonate and boiled for averagely 2 hours.
Then, the samples were cleaned and left in an oven for it to dry.Dried samples were brought for selection and identification of foraminiferal under binocular microscope.Photograph of well-preserved specimens was taken using image analyzer microscope by Leica.A clear photograph was used for further identification of species using previous research and references [13][14][15][16].

RESULT
Out of fifteen samples brought from the outcrops, twelve of it was successfully extracted to have benthic foraminifera which majorly consist of agglutinated and hyaline group.The species or genus was taken as references for its respective bathymetry level using several papers and books as references.Figure 2 and Figure 3 shows illustration of the selected benthic foraminifera.
The following genera and species of benthic foraminiferal found are arranged based on using some research study.Species found was majorly agglutinated and calcareous walled with a total of 19 genuses was collected of a perfect specimen.

Ammosphaeroidina sp.
Plate 1-figs.1, 2, 3 The species was formerly known as Cystamminella pseudopauciloculata by Majatliuk (1966).Taxonomy: Genus Ammosphaeroidina Cushman 1910 -Order Foraminiferida, Suborder Textulariina, Superfamilia Haplophragmiacea, Familia Ammosphaeroidinidae, Subfamilia Ammosphaeroidininae, Genus Ammosphaeroidina Occurrence: 405 specimens from 12 samples Feature: This specimen has a test that is enrolled streptospirally with an involute and three chambers that shows in outer whorl.Shape of the chamber is spherical, tightly embraced which increase rapidly in size.While the aperture is a basal slit, when visible, the walls are surrounded by a perforated wall of finely agglutinated surface.Bathymetry: Outer Neritic to Abyssal -Order Foraminiferida, Suborder Rotaliina, Superfamilia Bolivinacea, Familia Bolivinidae, Genus Brizalina Occurrence: 1 specimen (Te03) Feature: Consist of biserial test that elongate upwards more than width.Compressed side view, chambers are many but seven to eight visible divided by curved and depressed sutures.Perforation of the wall can be seen but considerably smooth with aperture clearly seen from base extending with tooth plate.Bathymetry: Abyssal

Brizalina aliformis Houlborn 2013
Plate 2-figs.3Originally designed as Bolivina Mexicana Cushman var.aliformis Cushman 1926 Occurrence: 1 specimen (Te03) Feature: an elongated and strongly compressed test that can be seen as biserial growth series.The test are surrounded by keel almost transparent, with chambers imbricating the younger part of the next chamber, separated by strongly curved limbate.Sutures seen are becoming thicker along the centre part of the test with numerous chamber of calcareous wall but finely perforated.Aperture can be seen like a loop with lip.Bathymetry: Abyssal

Cibicidoides bradyi Trauth 1918
Plate 2-figs.14 Taxonomy: Genus Cibicidoides Thalmann 1939 -Order Foraminiferida, Suborder Rotaliina, Superfamilia Discorbinellacea, Familia Parrelloididae, Genus Cibicidoides Occurrence: 5 specimens from 3 samples (Tte02, Te03, Te09) Feature: Trochospiral tests, unequally biconvex cross-section, rounded periphery, inflated chamber mostly nine to ten in the last whorl and separated by radial sutures.Calcareous walls with coarse perforation on spiral side but smooth perforated on the umbilical side.Aperture are narrow and slit opening with lips extending onto the spiral side.Bathymetry: Bathyal to abyssal.Occurrence: 3 specimens from 2 samples (Te01, Te11) Feature: The test is triserial series that enlarge rapidly as it grows and last three chambers are distinctly bigger that the other.It has periphery that lobulate slight in shape but rounded and inflated chambers can be seen along with depressed sutures.Aperture found at the end of apertural face, arching with flattened tooth.

DISCUSSION
Generally, all the samples that were successfully extracted consist majorly of agglutinated foraminifera and several hyaline groups.All the identified genus and species before was used to do analysis of bathymetry and is presented in Table 1.A total of 37 species were perfectly extracted.Meanwhile, Bolivina sp. and its genus, Cyclammina sp., Gyrodinoides girardanus, Hanzawaia mantaensis, Lagena striata, Nodosaria rudis, Textularia agglutinans, Bathysiphon discretus, Bathysiphon sp., Nodosaria anomala, Nothia robusta and Uvigerina hispida are grouped as the assemblages of abyssal environment.Thus, it can be stated that the samples and the formation of the outcrop is deposited in bathyal to abyssal environment.All the species recorded are present in Upper Abyssal condition which could be the exact depositional of the sediments.
The species found show some distinction with previous work of a researcher, where several species is either absent or badly preserved specimen.Karreriella sp., and Trochammina sp. was merely found to absent making the assemblages of certain are quite incomplete.The depth of research including distribution of species in paleoenvironments should be done to further the research and depositional modeling based on benthic assemblages and distribution.
A different research on benthic foraminifera was done by a researcher the Kudat Formation and the Crocker Formation on smaller benthic presence in mudstone.With high number of agglutinated and calcareous benthic present, the assemblage of foraminifera for Kudat Formation was said to be sediments ranging from bathyal to neritic.Meanwhile, Temburong Formation is of Bathyal to Abyssal range.

CONCLUSION
The benthic foraminifera of the Temburong Formation are rich in deep sea agglutinated foraminifera consisting of two major assemblages measured up to sedimentation environment from bathyal to abyssal.All of the species found are mostly in upper abyssal depth environment.

Figure 3 :
Figure 3: Illustration of results for benthic foraminifera.

sp. 1
Smaller test compare to Cyclammina sp. 1, with a glossy test.The walls are perforate-like feature with sutures are depressed and can be seen 13 to 15 chambers.It also has a large aperture in the apertural face.

.11 Gyroidinoides girardanus (Reuss), Beckmann 1953
Smooth wall, with 8 or 9 chambers of the last whorl for the specimen.Aperture is basal slit with large opening and slightly inflated.

.16 Nothia robusta Kender et al. 2008 (Grzybowski 1898)
Test elongate and forms biserial into uniserial series.Slight inflated chambers with uniserial part arched centrally.The chambers have curved strong sutures on a calcareous wall which is finely perforated and an aperture of radial or denticulate rim shape.Bathymetry: Lower Neritic To Middle Bathyal 1ccurrence: 5 specimens from 3 samples (Te01, Te11, Te12) Feature: species are quite large, robust and tubular.They are reported to be rarely branching with in constriction or inflation, straight or slightly curved shape.Bathymetry: Upper Abyssal4.1.17PlectofrondiculariavaughaniCushman 1927Plate 2-figs.1

.19 Reophax cf. troyeri Houlborn et al. 2013
The agglutinated walls made the chambers look quite unclear but can be seen it is interfingering with corresponds chamber.The last chamber can be clearly seen elevated slightly than the one before making it a cupped-like feature.The triangular test has slit aperture with coarsewalled.almost rectangular test with triserial growth, longer than wider especially the midlle part of it.The walls have four to five longitudinal basal spines, on a chamber that increases in size greatly at later stages, separated by depressed sutures.A thin elongated neck has terminal apertures at the end bordered by a phialine lip.Feature: the test seen is triserial series which elongate in adult one.Length should be as twice as the width but widest part is the one nearest to the apertural face.Size of chambers increases fast as it grows but the chambers are inflated with fine perforation, hispid wall, covered with narrow spines all over the chamber wall.A short-raised neck holds a round-shaped aperture.

Table 1 :
Tabulation of foraminifers' distribution in the samples