BIOSTRATIGRAPHY AND PALEOECOLOGY: HISTORY OF SAMBIPITU FORMATION EARLY –LATE –LATE MIOCENE IMPLICATED BY FORAMINIFERA FOSSIL *Harman Dwi R.(1), Moch Rahmat R. (2), Adnan W. (2), Ryan A. (2), Abraham I. P. (2) (1) Departemen Teknik Geologi, Fakultas Teknik, Universitas Gadjah Mada Jln. Grafika 2 Yogyakarta 55281, Indonesia (2) Fakultas Teknologi Mineral, Jurusan Teknik Geologi, Universitas Pembanguan Nasional “VETERAN”, Yogyakarta, Jl.SWK 104 (Lingkar Utara) Condongcatur, Yogyakarta 55283 Fax. 4864000
ABSTRACT
benthic sensitive to ecological changes and lithostratigraphy which show changes in deposition environment. Foraminifera is a very unique organism with the development of the marine region, with the distribution of rocks recorded in the sequence of stratigraphy Sambipitu Formation used in this study as a tool to identify deposition environment and paleoecology.
Understanding of ecology in the past, present and future temperatures can be possible to do by analysis abundance of fossil foraminifera. This research was conducted in Sambipitu Formation, Ngalang River, Nglipar, Gunung Kidul Regency. The research method is spatial, observation and sampling every 5 meters, Descriptive, analyzing samples consisting of a 10gram sample, biostratigraphy analysis and paleoecology analysis using abundance of fossil, diversity analysis, and comparing current temperature data. Biostratigraphy used as a parameter in assisting the determination of paleoecology, which can be evidence of changes of ecology at a certain age seen datum and biozones. Based on paleontological analysis found appearance and abundance of foraminifera bentonic which characterize the salinity environment in the Sambipitu Formation with early-to-late miocene. as well as the results obtained by fauna association (foraminifera), that the study area showed salinity normal marine water. From the analysis we found 1 phase of pelotemperatur based on appearance of Globorotalia menardii, Globigerinoides trilobus, Globigerinoides ruber, Orbulina universa, and appearance of Pulleniatina obliqueculata showing paleotemperature phase Warm Water Area and Warm Water Area (average surface water approximate 25oC).
2. SETTING GEOLOGY The southern mountainous zone, is a structural mountain range that extends from west to east in the direction of Java Island geometry, and is divided into the southern mountains of East Java and the western mountains of western Java. So what is meant by the southern mountains is the mountains located in the southern part of Central Java, starting from the southeastern part of the province of Yogyakarta Special Region, extending eastward along the southern coast of East Java. From the conclusion of the results of previous researchers, which lies to the south and southeast of Wonogiri-Baturetno depression stratigraphy order compiled by Sartono (1958). The constituent rocks at the bottom consist of coarse sandstones, then up gradually into fine sandstone alternating with flakes, rocks and clay.At the bottom of this rock group does not contain carbonate material or the sandstone still shows volcanic properties. But the more these volcanic properties change, especially sandstones, containing carbonate material. In this sandstone is often found fragments of coral and large foraminifera derived from the shallow marine environment, which dragged into the deeper environment due to the influence of turbid currents. Formation Sambipitu have a position of fingers and aligned above Nglanggran Formation.
Keywords: Abundance, Biost ratigraphy, Paleoecology, Sambipitu Formation. Formation. 1. INTRODUCTION Paleoecology is ecology in the past. At the Early – Late miocene the study area showed an environmental change, which has fluctuations due to changes in space and time. The paper is integrated in paleontological analysis that analyzes fossil foraminifera plankton and
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They can be used to reconstruct past climate by examining the stable isotope ratios and trace element content of the shells (tests). Global temperature and ice volume can be revealed by the isotopes of oxygen, and the history of the carbon cycle and oceanic productivity by examining the stable isotope ratios of carbon δ18O and δ13C. Geographic patterns seen in the fossil records of planktonic forams are also used to reconstruct ancient ocean currents. Because certain types of Foraminifera are found only in certain environments, they can be used to figure out the kind of environment under which ancient marine sediments were deposited. Fig. 2. Stratigraphy by previous researchers (Bothe (1929), Van Bemmelen (1949), Surono, et al. (1992))
4. BIOSTRATIGRAPHY
Biostratigraphy is the branch of stratigraphy which focuses on correlating and assigning relative ages of rock strata by using the fossil assemblages contained within them. In previous researchers stated that the age of Sambipitu was early – middle miocene (Surono, 1992) and there is a middle miocene (Van Bemmelen). In this study using the classification of B.S Wade (2011), in 2009 the reasearch of Integrated Ocean Drilling Program (IODP) Wade has analysis biostratigraphy using foraminiferal is extensively employed during shipboard and establish age-depth relationships. In this research obtained three datums: Datum Globigerinoides primordius; Globogerinoides altiaaperturus; and Globorotalia plesiotumida. Datum Globigerinoides primordius obtained on Sn 39 samples was 24.3 Ma. Datum Globogerinoides altiaperturus on samples Sn 31 aged 20.50 Ma. As for Datum Globorotalia plesiotumida on Sn 9 sample 8,58 Ma. And than the calibration is performed using zonasi Blow, 1969. 4.1. Globoquadrina dehiscens zone N4a dehiscens This zone, with the age of the early Miocene, attributed by first appearance in Globoquadrina dehiscens as a first occurrence to Globoquadrina altispira. N4a zone composed of sandstones and looping rock units of the shale stone where the abundance of fossils are abundant enough Globoquadrina dehiscens (Medium 20 – 30 specimens). 4.2. Globigerinoides primordius zone N4b This zone, with early Miocene age, characterized by the Globigerinoides primordius first appearance to the first occurrence Globigerinoides trilobus. N4b zone composed of rock units and shale stone looping sandstones where an abundance of fossil Globigerinoides primordius is abundant (ambundance > 50 specimen). 4.3. Globigerinoides obliquus zone N5
3. MATERIALS AND METHODS In this study the researchers conducted a measured section on the outcrop with 62 meters thick in the formation sambipitu. Precisely this research is in Ngalang which is the geoheritage area of Gunungkidul precisely in Yogyakarta Special Region. At the top is limited by Oyo Formations with clastic carbonate rocks and the bottom by Ngelanggeran Formation with rock breccia and volcanic rocks. In this area there is abundant bioturbation at the bottom and small foraminifera fossil content. This study focuses on the distribution of foraminifera which is used as biostratigraphy and paleoecology interpretation and stratigraphy data used for sequence stratigraphy on sambipitu formation with early-late miocene.
Fig. 1. Research Sites located on the Ngiono River. 3.1. FORAMINIFERA Foraminifera are members of a phylum or class of protists. Foraminifera typically produce a test, or shell, which can have either one or multiple cha mbers. These shells are commonly made of calcium carbonate (CaCO3) or agglutinated sediment particles. Because of their diversity, abundance, and complex morphology, fossil foraminiferal assemblages are useful for biostratigraphy, and can accurately give relative dates to sedimentary rocks. Calcareous fossil Foraminifera are formed from elements found in the ancient seas where they lived.
This zone, with early Miocene age, at the interval of the first attributed by appearance Globigerinoides obliquus to first occurrence Globigerina seminulina. Zone N5 unit of rocks composed of sandstones with perselingan shale stone and breksi where the abundance of fossil Globigerinoides obliquus is medium (Medium 20 – 30 specimens).
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4.4. Globigerinoides diminutus zone N6a
5. PALEOENVIRONMENT The research area is dominated by carbonate sandstone which is clastic sedimentary rock grain size ranges from gravel to very fine sand. Then there are also some structures recorded on the sandstone including wavy laminate, inverse graded bedding, laminate and crossbedding (Fig. 3.).
This zone was early Miocene, with interval from first appearance to the first occurance Globigerinoides diminutus, Globigerinoides altiaperturus. Penyusunya rocks are sandstone units with inset shale stone where an abundance of fossil Globigerinoides diminutus is medium (Medium 20 – 30 specimens). 4.5. Globigerinoides altiaperturus zone N6b This zone was attributed to early Miocene gift fisrt appearance Globigerinoides altiaperturus to the first occurance Globorotalia peripherorondes. N6b zone composed of rock units of the sandstones with inset shale stone. The abundance of Globigerinoides altiaperturus is medium (Medium 20 – 30 specimens). 4.6. Globorotalia peripherorondes zone N6 – N12 This zone is characterized by the appearance of the first Globorotalia peripherorondes to the first occurance Sphaeroidinella subdehiscens with the age of the early Miocene – Middle Miocene. rock units of the compiler of this zone is sandstones. The abundance of Globorotalia peripherorondes is medium (Medium 20 – 30 specimens). 4.7. Sphaeroidinella subdehiscens zone N13 This zone of the Middle Miocene age with the appearance of the first identifier Sphaeroidinella subdehiscens to the first occurance Globorotalia nepenthes. This zone is structured upon the rocks of sandstone with looping unit shale stone. An abundance of Sphaeroidinella subdehiscens is a medium (Medium 20 – 30 specimens). 4.8. Globigerina Nepenthes zone N14 This zone is characterized by first appearance Globigerina nepenthes to the first occurance of Globorotalia plesiotumida, Middle Miocene age. Rock units of the compiler of this zone is looping sandstones and shale stone. The abundance of fossil Globigerina nepenthes is abundant (Medium 20 – 30 specimens). 4.9. Globigerinoides immaturus zone N15 This zone was the late Miocene with the appearance of the first identifier Globigerinoides immaturus. Units constituting rocks are sandstone and shale stone looping. The abundance of fossil Globigerinoides immaturus is abundant (Medium 20 – 30 the specimen).
Fig. 4. A, Sn31 Ichnofossil, B, Sn27 Wavy Lamination, C, Sn26 Inverse Gradded bedding, D, Sn31 lamination, E, Sn33 Cross lamination. 5.1. SEQUANCE STRATIGRAPHY 5.1.1. SEQUENCE BOUNDARY In the study area there were five sequence boundaries, SB1, SB2, SB3, SB4, and SB5 which have been observed based on changes in rock texture and benthic foraminifera content. The entire sequence boundary is characterized by a decrease in paleobatimetry recorded on rocks. 5.1.2. LOWSTAND SYSTEM TRACK (LST) There are five observed LST hoses. The LST is usually indicated by altered paleobatimetry changes and then the fossil diversity of both planktonic and benthic foraminifera. LST deposits are usually characterized by the presence of fossils rework and mixing of shallow deep and shallow seawater foraminifera. 5.1.3. TRANSGRESSIVE SYSTEM TRACK (TST) In the study there were six TST, TST hose showed a deepening of the basin tends to show greater abundance of foraminifera plankton than benthic foraminifera. So it can be known if the process of deepening will usually show abundance of more plankton foraminifera. 5.1.4. HIGHSTAND SYSTEM TRACK (HST) There are five observed HSTs, indicating increasingly shallower with declining diversity and abundance. 5.1.5. TRANSGRESSIVE SURFACE (TS) There are five TS points where each TS indicates a relatively shallow depth environment - in characterized by permanent silting. Relatively shows the decline in
Fig. 3. List of fossils
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emergence of the Globorotalia menardii fossil, Globigerinoides trilobus, Globigerinoides ruber, Orbulina universa, and Pulleniatina obliqueculata showing the paleotemperature phase of the Warm water tropical area (Banerji, Schaper & Vine, 1971). Compared with the current temperature does not experience a significant temperature change where the current temperature indicates 35oC. 6.2. PALEOSALINITY Analyzing 18O data they also found that deep waters were within error of the freezing point, with oceanic waters exhibiting a greater degree of homogeneity in temperatures. In the result of abundance analysis of benthos foraminifera to know paleosalinity of some genus obtained normal marine. The benthos genus belongs to the stenohaline which means that the genus is only able to survive under normal marine conditions. Genus derived from an abundance analysis based on Murray 1973: Cibicides normal marine life in artictripical, shelf-bathyal, Cassidulina normal marine with cold temperature, shelf-bathyal, Lenticulina normal marine with cold temperature, outer shelf and bathyal, Cyclammina normal marine with temperature 10 oC, outer shelf and top bathyal, Textularia normal marine with artic tropical temperature, shelf and top bathyal. Gaudryina normal marine with medium temperature, upper bathyal shelf, Lagena normal marine with cold tropical temperature, shelf, Trochammina normal marine cold temperature, shelf-bathyal, normal marine Planorbulina with temperature subtropical, inner shelf, normal marine Eponides with normal temperatures, Quinquelloculina marine shelf bathyal and hypersaline lagoon with medium temperature - tropical, slight Globobulimina, hyposaline and normal marine with temperature <10o, Normal Marine normal with cold temperature, outher shelf and bathyal, Amphistegina temperature 25-26oC, inner shelf. The trend of fossil fossil presence in each sample shows a uniform abundance of no change in abundance though so researchers assume that no extreme salinity event occurs. 6.3. PALEOBATIMETRY Paleobathymetry the determination of ancient water depth is the paleoenvironmental interpretation. Benthic foraminifera are usually used for this purpose. As bottom dwellers, they provide information about conditions at the sea floor. Many species live within a relatively limited range of water depths in patterns normally related to water mass distribution within the basin rather than directly to bathymetry. Reconstruction of paleobatimetry based on data from benthic foraminifera fossils. Based on the result of the reconstruction, there was a strong retrogradation process shown in Sn 31-30 samples with depth reaching 1400 - 1450 asl (above sea level) at early miocene stage and the highest progradation process reaching height 165 - 175 m at middle miocene moment shown in Sn 15-14 samples.
abundance and diversity of both plankton and benthic foraminifera. 5.1.6. MAXIMUM FLOODING SURFACE (MFS) In the study there were as many as six times the MFS which showed an abundance of plankton foraminifera with varying diversity, followed by the difficulty of the difference between foraminifera which is a rework and insitu because sea level changes quite quickly. 6. PALEOECOLOGY Paleoecology is study of interactions between organisms and interactions between organisms and their environments across geologic timescales. The aim of paleoecology is to build the most detailed model possible of the life environment of previously living organisms found today as fossils. Often much of this information is lost or distorted by the fossilization process or diagenesis of the enclosing sediments, making interpretation difficult. 6.1. PALEOTEMPERATURE Understanding temperatures occurring in the past, present and predict future temperatures can be done by utilizing the analysis of the abundance of foraminifera. The foraminifera fossil is a reference for planktonic foraminifera because this planktonic foraminifera fossil is thought to interpret the temperature data more accurately on the surface. Banerji, Schaper & Vine (1971) conducted a paleotemperature study based on planktonic foraminifera located in the equator and the North Pacific Ocean. From the results, there are five zones of Warm water tropical area, Warm temperate area, Cosmopolitan species, Cold temperate area, Cold water area. Table 1. Table of fauna association equator area and North Pacific Ocean according to Banerji, Schaper & Vine (1971).
Area
Fauna
Warm water tropical area (average surface water approximate 25oC).
Gla. aequilateralis, Gs. conglobatus, Gs. ruber, Gs. sacculiferus, Gs. trilobus, Gr. menardii, Gr. tumida, Orbulina universa, Pulleniatina obliqueloculata, Sphaeroidinella dehiscens. Etc.
Warm temperate area (average surface water app. 20oC)
Gr. infilata, Gr. hirsuta, Gq. dutertrei (and some water species)
Cosmopolitan species Cold temperate area (northern boundary app. At 10oC isotherm)
Globigerina glutinata, Gr. inflata (in surface) G. bulloides, G. pachyderma (dextral), Gr. inflata ( some cosmopolitan species and warm water species )
Cold water area (average surface water at temperature less 10 oC).
G. bulloides, G. pachyderma (sinistral), Gq. dutertrei (small forms), Gr. cavernula, Globigerinita glutinata.
From the analysis of planktonic foraminifera fossils obtained a phase of paleotemperature based on the
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calibration to the geomagnetic polarity and astronomical time scale, Earth-Science (2011). Khoiril Anwar M., Sebaran foraminifera dalam hubungannya dengan stratigrafi sikuen (Studi kasus: daerah Blora dan seitarnya/daerah lintang rendah), PROC. ITB, Vol 30, (1998). Sartono, The Stratigraphy and Sedimentation of the Most Eastern Part of the Gunung Sewu, (1958). Van Bemmelen, Report on the volcanic activity and volcanological research in Indonesia during the period 1936 –1948, Springer (1949). Banerji,et al, Environmental relationships and distribution of planktonic foraminifera in the equatorial and northern Pacific waters: Dep. Energy, Mines, Res, Marine Science Branch, Atlantic Ocean Laboratory(1971). Muray, 1973 Distribution and ecology of living benthic foraminiferids, agris.fao.org (1973).
7. RESULTS AND DISCUSSION In this research obtained three datums: Datum Globigerinoides primordius obtained on Sn 39 samples was 24.3 Ma, Datum Globogerinoides altiaperturus on samples Sn 31 aged 20.50 Ma, As for Datum Globorotalia plesiotumida on Sn 9 sample 8,58 Ma, In the study area there were five sequence boundaries, SB1, SB2, SB3, SB4, and SB5 which the entire sequence boundary is characterized by a decrease in paleobatimetry recorded on rocks, there are five observed LST hoses, usually indicated by altered paleobatimetry changes and then the fossil diversity of both planktonic and benthic foraminifera, there were six TST hose, show greater abundance of foraminifera plankton than benthic foraminifera, there are five observed HSTs, indicating increasingly shallower with declining diversity and abundance, there are five TS points where each TS indicates a relatively shallow depth environment - in characterized by permanent silting. Relatively shows the decline in abundance and diversity of both plankton and benthic foraminifera, there were as many as six times the MFS which showed an abundance of plankton foraminifera with varying diversity, followed by the difficulty of the difference between foraminifera which is a rework and insitu because sea level changes quite quickly. Paleoecology, From the analysis of fossils obtained paleotemperature phase of the Warm water tropical area. Paleosalinity, The trend of fossil fossil presence in each sample assume that no extreme salinity event occurs. Paleobatimetry, there was a strong retrogradation process with depth reaching 1400 1450 asl (above sea level) at early miocene stage and the highest progradation process reaching height 165 175 m at middle miocene moment.
11. PHOTOS AND INFORMATION Harman Dwi R. received the S.T.
(2016) He with the Master Program of Departemen Teknik Geologi, Fakultas Teknik, Universitas Gadjah Mada Jln. Grafika 2 Yogyakarta 55281, Indonesia. His Current interests include Stratigraphy, Sedimentology and Paleontology Moch Rahmat Ramdhani. received
the student collage of Geological engineering from UPV “Veteran” Yogyakart. . His Current interests include Stratigraphy, Sedimentology and Paleontology.
8. CONCLUSIONS The pattern of distribution of foraminifera can be used as a reference to determine the deposition environment and paleoekologi when data taken in detail or referring to previous researchers. The role of foraminifera is also important as determination of age (biostratigraphy), as well as the identification of sequences and track systems. Paleoecology use of plankton and benthic foraminifera can be a problem solver in discussing paleobatimetry, paleocalinity, and paleo temperature.
Adnan Widodo. received the student
collage of Geological engineering from UPV “Vet eran” Yogyakarta. His Current interests include Stratigraphy, Sedimentology and Paleontology.
Ryan Avirsa. received the student
collage of Geological engineering from UPV “Veteran” Yogyakarta. His Current interests include Stratigraphy, Sedimentology and Paleontology.
9. ACKNOWLEDGMENT The authors thank the staff of the paleontology laboratory in UPN “Veteran” Yogyakarta. This research was supported by Paleontology Research. 10. REFERENCES C. Waelbroeck, et al, Sea – level an deep water temperature changes derived from benthic foraminifera isotopic records, Quaternary Science Reviews 21 (2002). Wade, et al, Review and revision of Cenozoic tropical planktonic foraminiferal biostratigraphy and
Abraham Ivan P. received the
student collage of Geological engineering from UPV “Veteran” Yogyakarta. His Current interests include Stratigraphy, Sedimentology and Paleontology.
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Fig. 5. Analysis paleoecology and biostratigraphy
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