E-ISSN : 2541-5794
P-ISSN : 2503-216X
Journal of Geoscience,
Engineering, Environment, and Technology
Vol 02 No 04 2017
242 Winantris & Jurnaliah, L./ JGEET Vol 02 No 04/2017
Pollen and Foraminifera Approaches to Identify
Sediment Sources In The River Mouth Mahakam
East Kalimantan
Winantris
1,
*, and Lia Jurnaliah
1
1
Faculty of Geology, Universitas Padjadjaran, Jl. Raya Bandung Sumedang Km.21, Kabupaten Sumedang, West Java 45363
* Corresponding author : win.oncos@gmail.com
Received: Sept 1, 2017. Revised : Oct 1, 2017, Accepted: Nov 9, 2017, Published: 1 Dec 2017
DOI : 10.24273/jgeet.2017.2.4.689
Abstract
The central role of Mahakam River in the construction of Mahakam Delta is to supply sediment from terrestrial to the
river mouth. The river upstream comes from Mount Camaru and the downstream part terminate at Makasar
Strait. The surrounding area of the river is overgrown by wet tropical flora that produces pollen. The existence pollen in river
sediments as an indicator that sediment came from terrestrial, and foraminifera as an indicator that sediment came
from marine. The ratio changes of pollen to foraminifera show that there were differences of sediment source supply. The
study was conducted at the river mouth. A shallow core, 200 cm depth, composed of sand and mud and sandy mud, from it
taken vertically 11 samples to be analyzed pollen and foraminifera. Sample preparation was using standard methods
acetolysis. Meanwhile, sample preparation of foraminifera using Hydrogen Peroxide method. Pollen found in all samples,
but foraminifera only found in 8 samples. The data indicating that sedimentation process in the mouth of a river not only
gets sediment supplies from terrestrial but also from marine. The quantity of pollen and foraminifera varies vertically. The
frequency of pollen much higher than foraminifera that indicates of source sediments dominance came from terrestrial
which carried by Mahakam river current. Sonneratia caseolaris pollen continuously found in all samples.
Stictogongylus vandiemensis is species foraminifera the most common that followed by Ramulina confossa, both of them
come from the sea particularly from the shallow sea.
Keyword: Pollen, foraminifera, sediment source, mouth of Mahakam River
1. Introduction
The river mouth is the place where a river
enters a lake, larger river, or the ocean is called its
mouth (Merriam-Webster,1828). The Mahakam
River is an icon for the Province of East Kalimantan.
Mahakam River upstream rises in
Mount Cemaru that empties into the Makassar
Straits. The position of a river mouth in the
upstream from Mahakam Delta. The main role of
the Mahakam river in the delta formation is
supplying sediment to the estuary area.
The Province of East Kalimantan, the place
of Mahakam River is located in the equatorial area
(Fig.1).
The landscape along the Mahakam River
overgrown by various types of tropical flora. In the
upstream section, there are hilly areas that
inhabited by tropical rainforest that located in the
district of Mahakam Hulu.
Mahakam river is generally covered by
vegetation of lowland forest and mixed forest.
Entering the delta plains area there are swamp
forests which dominated by Nypa fruitcans and
secondary mangrove plant, the true mangrove
grows at the end of the delta plains, precisely in the
area of mud flats (Winantris, et.al 2013, Fig.2).
The existence of tropical forest plants along the
river, makes sediments transported to the estuary
filled with pollen which produced by forest plants.
This is one reason why research is done. The study
aims to identify the types of pollen found in
sediments that before entering the Mahakam delta.
It is important to know the type of pollen that fills
a river as a tool to identify the source of sediment
deposited at the mouth of the river before entering
delta area. Benthic foraminifera classically used as
an indicator of marine depositional environments,
in particular, to detect the ocean depths
(bathymetry), it is closely related to the way of
living foraminifera are attached to the seabed. Both
pollen and benthic foraminifera have a similar
function in this case for identifying the source of
sediment.The Mahakam delta is a mixed, river and
tide-dominated delta (Galloway, 1975). The delta
characterized by a mixture of sediment from the
river and the sea. Furthermore, the delta is
presently in a transgressive phase (Salahuddin and
Lambiase, 2013). Tide rise in Mahakam Delta
Winantris & Jurnaliah, L./ JGEET Vol 02 No 04/2017 243
triggered by the waves that come from the
Makassar Straits which cause water accumulation
in the delta plain area (Allen and Chamber, 1998).
High tides are also as transport media of sediment
from the sea to the delta region
Evidence that the tide rise could encourage
marine sediments towards the river mouth by
looking for the presence of foraminifera in
sediment. Kind of foraminifera is an indicator of
the marine bathymetry of the origin sediments.
Referring to the bathymetry and habitat
classification of benthic foraminifera, it will be
known the depth of sedimentary origin which is
transported and deposited at the mouth of the
river comes. Likewise, the source of sediments that
comes from upstream can be traced by the pollen
data. Pollen analysis is one of foundation for
reconstructing past ecosystems, by fossil pollen
preserved within accumulating sediment whose
provenance can be identified back to the parent
plant (Lovett, et.al 2007).
Fig.1 Location of Mahakam River (Duxbury, 2010)
Fig. 2 Vegetation zone of Mahakam Delta (Winantris, et.al.2013).
244 Winantris & Jurnaliah, L./ JGEET Vol 02 No 04/2017
2. Material and Methods
A shallow core taken at the mouth of the
Mahakam river with a depth of 200 cm, from it
taken 11 samples at intervals of 20 cm for the
analysis of pollen and foraminifera, consist of: MR-
1 (0 cm), MR- 2 (20cm), MR-3 (40cm), MR-4
(60cm), MR-5 (80cm), MR-6 (100cm), MR-7
(120cm), MR-8 (140cm), MR-9 (160 cm), MR-10
(180cm) and MR-11(200cm). The position of
sample location at Mahakam River upstream from
the delta (Fig.3).
Sample preparation for the palynological
analysis was done using acid treatment method.
Each sample was taken 10-gram dry weight for
pollen analysis, and only 0,5 ml/slide from the
residue of the sample that observed. Identifying
pollen used light binocular microscope under high
magnification x100, 400x and 1000x, and scanning
electronic microscopy. Pole observation used LO
analysis method. To get a clear pollen morphology
the picture was taken under magnification 1000x.
The same as pollen treatments, for the analysis of
foraminifera are also using 10 gr dry
weight/sample. Processing sample of foraminifera
used Hydrogen Peroxide method, and for
observation using a binocular microscope.
Identification of foraminifera refers to Lobliech &
Tappan (1994). Meanwhile, the ocean depths refer
to the classification of bathymetry (Tipsword et al
1966), see Fig 4.
3. Pollen analysis
The shallow core consists of sand and silt
sediment, from a depth of 200 cm to 131cm
consists of fine sand, medium and coarse sand.
From the depths of 131cm up to the surface at
position 0 cm composed of silts and clay. All
samples which analyzed found the pollen. The total
pollen sum of sand sediment only 30 to 70 grains
in each sample, that include the poor to moderate
category, and average just 51,2 grains/sample.
Different from silt sediment, pollens found more
than in sand sediment. Minimum pollen is
126 grains at MR-3 and maximum 256 grains at
MR-4, pollen average reach 210,83
grains, it's belong rich category (Table 1and Fig.7).
Fig 3. Spot location of study at Mahakam River, Kalimantan.
Winantris & Jurnaliah, L./ JGEET Vol 02 No 04/2017 245
Fig.4 Classification of bathymetry (Tipsword et. al,1966).
Table 1. Pollen quantity
Sample code Depth (cm) Pollen (grains)
MR-1 0 254
MR-2 20 232
MR-3 40 126
MR-4 60 256
MR-5 80 180
MR-6 100 217
MR-7 120 52
MR-8 140 52
MR-9 160 52
MR-10 180 70
MR-11 200 30
The data illustrate that there were a supplied of
sediment from the mountains, surrounding the
upstream area, besides from the lowland and the
environment around the river mouth. The role of
Mahakam River as an agent to supply pollen from
upland to downstream area. Pollen of Montane
Forest Zone which found consist of Altingia exelsa,
Arenga pinnata, Celtis sp, Dacrycarpus imbricatus,
Engelhardtia sp, Erica sp, Ilex
sp,Phyllocladus hypophyllus, Pinnus sp, Podocarp
us neriifolius, Quercus laurifolia, Taxodium sp and
Vaccinium sp.
Pollen of Altingia exelsa, Arenga pinnata
and Celtis sp produced by vegetation
of Submontane Forest Zone that grows an altitude
1000- 1500 m above sea level.
Dacrycarpus imbricatus, Podocarpus neriifolius,
Quercus laurifolia, Engelhardtia sp derived from
Lower Montane Forest zone which occupies an
area at an altitude of 1400-1800 m above sea level.
Specifically, Vaccinium sp and Erica sp both are a
type of pollen from the Upper Montane Forest that
occupies an area at an altitude of 2400-3000
meters above sea level (Whitmore, 1975; Stuijts,
1933). Vegetation in the downstream area consists
of Lowland Forest, Mixed Forest, Swamp Forest and
mangrove forests, and in the upstream area, there
are Montane Forests.
Based on the quantity of pollen can be known
that the pollen from the vegetation in the
downstream area is the most common. Generally,
there were mixed pollens which produced by
mangrove, swamps, vegetation, lowlands and
mountain vegetation (Fig.5) Pollen from lowland
forest more various than from upland. The species
that commonly found are Eugeissona insignis,
Dipterocarpus sp. and Cocos nucifera. Sonneratia
alba is the most mangrove pollen, while Nypa
fruit cans andOncosperma tigillarium are common
pollen that comes from the delta plain. Based on
vegetation zone of Mahakam Delta, mangrove
pollen which produced by mangrove plant came
from mud flat area, that laid in the distal part of
lower delta plain. The existence of mangrove
pollen in the mouth of a river is indicated that there
was a mobilisation of pollen from distally lower
delta plain to the mouth of the river (Fig .8).
Fig. 5. Erica sp (1),.Dacrycarpus imbricatus (2),
Cocos nucifera(3), Oncosperma tigillarium (4),
Eugessona insignis(5), Vaccinium sp (6).
Microscope magnification 1000x).
1 2 3
4 5 6
246 Winantris & Jurnaliah, L./ JGEET Vol 02 No 04/2017
4. Foraminifera analysis
Small benthic foraminiferas were found in 8
(eight) sediment samples of 11 sediment samples
from river mouth Mahakam. Based on foraminifera
analysis there are 13 species and 56 specimens.
The
specimen, found in MR-9 sample with 160 cm
species is 7 species, found in MR-11 sample with
200 cm depth. Fig. 7 shows that the amount of
foraminifera increased toward deeper core (Table
2).
Table 2. Quantity of foraminifera
Sample code Depth (cm)
Species Specimen
MR-1 0 2 4
MR-2 20 2 2
MR-3 40 0 0
MR-4 60 0 0
MR-5 80 0 0
MR-6 100 2 2
MR-7 120 3 8
MR-8 140 3 3
MR-9 160 6 19
MR-10 180 2 3
MR-11 200 7 15
Total 56
Discover of small benthic foraminifera in the river
mouth area are evidence of the energy came from
sea direction. Tidal wave have a role to encourage
the sediment from the sea towards the
downstream of Mahakam river. (Fig.6)
The chart shows the quantity of foraminifera in
the sand sediment is a significant differ from silt
sediment. The quantity of Foraminifera from sand
more common than from silt sediment. Inversely
condition with mud sediments that showing the
quantity of pollen is very high (Fig.7). There are no
benthic foraminifera in 40 cm-80 cm depth. Lack
of benthic foraminifera in those interval shows that
the source sediment from terrestrial. This
condition is significantly different from sand
sediment in 120 cm-200 cm depth which is small
benthic foraminifera is more common. It means
that in deeper core the source sediment not only
came from terrestrial but also came from marine
(Fig 8).
The species of small benthic foraminifera in all
sample sediments include shallow species such as
Reusoolina stellula and Stictogongylus
vandiemenensis, and deep species such as
Uvigerina bradyana. Those foraminifera
assemblages are evidence of sediment marine
came from shallow sea and deep sea.
The presence of benthic foraminifera in the river
mouth sediment, possibly related to the
transgressive phase in the modern delta area.
Salahuddin and Lambiase (2013) found benthic
foraminifera in the Nypa swamp area which
located on the delta plains, they said that the
sediment of modern delta shows the transgression
product.
(1) (2)
Fig.6 Reusoolina stelulla (1), Stictogongylus vandiemenensis (2),
(Microscope magnification 56x)
Winantris & Jurnaliah, L./ JGEET Vol 02 No 04/2017 247
Fig 7. Quantity of pollen (grains) and foraminifera (specimen)
= mud = sand
Fig. 8. Illustration of Source of sediment which filled mouth of Mahakam River based on origin of Pollen and
foraminifera
248 Winantris & Jurnaliah, L./ JGEET Vol 02 No 04/2017
5. Conclusions
The sources of sediment that fills the mouth of
the Mahakam River dominated by terrestrial
sediment and only a small portion of the sediment
from marine. About 77, 23% samples who have
observed, indicated that sediment supply from
terrestrial and marine, and 27.27% samples the
sediment supply only from terrestrial. The highest
presence of foraminifera only 25 %, contrary to its
pollen reaches 75% is the lowest presence of total
pollen-foraminifera in the 200 cm depth. After
that, the presence of foraminifera decrease and
reaches minimum in 80-40 cm intervals by 0% so
in the same intervals presence of pollen 100%
While the sources of terrestrial sediment include
from the delta and surrounding areas, lowlands
and highlands.Sediment from the ocean, covers
shallow sea and deep sea.
There were no benthic foraminifera at the
interval 40 cm-80 cm depth it indicates that the
source of sediment just comes from the mainland.
The differences in the depth of sediment source
that fills the mouth of the river indicate the
strength of tidal waves was triggered by a wave of
Makassar Strait also vary in the strength.
Acknowledgements
We are particularly grateful for the assistance
given by Maria who help us in processing samples.
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1. Introduction
2. Material and Methods
3. Pollen analysis
4. Foraminifera analysis
5. Conclusions
Acknowledgements
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