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Pattern analysis of organic component abundances from deltaic and open marine deposits: Palynofacies distribution (East Java, Indonesia)
Abstract
Eleven types of organic debris and thirty-one types of discrete organisms have been recognized in the surface samples obtained during research activities in Indonesia. The relative concentrations of these types have been submitted to reciprocal averaging and to cluster analysis. With reciprocal averaging two main groups can be distinguished: (1) open sea samples, characterized by the occurrence of identifiable remains of marine organisms, and (2) terrigeneously influenced samples characterized by the relative abundance of woody debris, pollen and spores. The clustering suggests that other depositional environments might be detected.
... Höhere Anteile opaker Phytoklasten können auch als Insitu-Oxidation gedeutet werden. Eine Voraussetzung für In-situ-Oxidation ist nach VAN WAVEREN (1989) eine niedrige Akkumulationsrate, es scheint aber eher unwahrscheinlich, dass dies für die bioklastischen Pack/Rudstones bzw. Wacke/Floatstones der Tempestite zutrifft. ...
... Meistens wurde bei palynofaziellen Untersuchungen ein Trend von gleichförmigen zu länglichen Phytoklasten mit zunehmender Entfernung von der Küstenlinie beobachtet (PARRY et al., 1981; VAN WAVEREN, 1989;WHITAKER, 1984). GORIN & STEFFEN (1991) berichteten von einer zunehmenden Sortierung und Abrundung opaker Partikel in sehr distalen Bereichen verbunden mit abnehmender Größe. ...
Aus: Jahrbuch der Geologischen Bundesanstalt (Wien) ; Bd. 144. 2004. Frankfurt (Main), Universiẗat, Diss., 2003.
... The 1ath:equant frequency ratio of black phytoclast particles has previously been used in palynofacies studies to indicate proximal-distal variations, because the proportion of lath-shaped particles generally increases in an offshore or distal direction (e.g. Parry ef al. Whitaker 1984;Van Waveren 1989;Gorin & Steffen 1991). However, in our study we observe that this ratio increases in a proximal direction (although the higher ratio in sample B15 may reflect the normal distal pattern). ...
The Early Carboniferous (Brigantian) Middle Limestone Group of Northumberland represents a prolonged period of rhythmic Yoredale-type deltaic sedimentation. Optical and geochemical analyses were undertaken on the minor Berwick Limestone Cyclothem, a prograding coarsening- and shallowing-upward cycle (parasequence) within the major Oxford Limestone Cyclothem. These indicate an overwhelming dominance of Type III-IV land-plant derived kerogen (woody phytoclasts). The hydrogen index shows a strong negative correlation with the palynologically determined black:brown phytoclast ratio. The total organic carbon content of the fine-grained lithologies increases upwards through the cycle and is positively correlated with silt content, presumably due to the hydrodynamic equivalence and common fluvial source of phytoclasts and silt particles. The lath:equant ratio of the black phytoclasts increases upwards through the cycle (i.e. in a proximal direction); this pattern is 'atypical' and results from the lath-shaped phytoclasts being larger than the equant ones. The section is marginally mature (about 0.64% vitrinite reflectance); reflectance is correlated with hydrogen index. The distribution of pyrite and siderite is apparently related to sediment accumulation rate, with siderite most common in the interval of probable highest sedimentation in the lower half of the cyclothem above the limestone. The marine flooding surface at the base of the cycle is overlain by black shale, not limestone; the traditional (limestone) base of the cyclothem does not correspond to the true base.
... Furthermore, the presence of Sordaria (Type 55A) could confirm the impact of grazing, since it is a fungal ascospore of coprophilous species (López-Sáez et al., 2000; van Geel, 2001). The percentage predominance of Foraminiferae (Type 700) among the NPPs, along with the presence of Tardigrada (Type 902) and Acritarche (Type 966), could indicate that in the chronological context of the sedimentary record of Portlligat Bay, the prevailing conditions could have been hyposaline (Van Waveren, 1989; Zamora et al., 2007). In the same way, the presence of Micrhystridium (Type 115) points to the marine nature of the record (Bakker and van Smeerdijk, 1982). ...
A high-resolution sedimentary sequence sampled from the Portlligat Bay (NE Iberian Peninsula) has been studied in order to assess its palaeoecological potential. This sedimentary sequence is considered a very particular one, as it is a peat-like deposit derived from the accumulation of the belowground dead parts of the marine phanerogam Posidonia oceanica through the last 1600 years. This study represents the first attempt to explore the palaeoecological potential of such deposits from a palynological point of view, and has allowed the reconstruction of the vegetation dynamics and changes, human impact and the palaeoclimatic characteristics, demonstrating the value of these sedimentary records in palaeopalynological studies.
The Rajang River and its delta accumulate siliciclastic sediments and dispersed organic matter within river and todal channels as rhythmically stratified sand, silt, and organic drapes. These deposits were vibracored and subsampled, resulting in a data set composed of 84 samples taken from 45 cores. Palynofacies preparations of this sediment facies were examined from throughout the alluvial valley and delta to determine if a single organic matter assemblage characterized these deposits. An underlying assumption of palynofacies analyses in ancient transitional settings is that each lithofacies or depositional environment is characterized by a specific organic matter (OM) assemblage. This specific hypothesis is no supported by the present investigation. However, the present investigation has demonstrated that the resultant dispersed OM assemblages within a single sediment facies is heavily influenced by the geochemistry of the system.
Three distinct palynofacies assemblages in this data set have been identified using nonparametric and multivariate statistical analyses. One assemblage, characterized by high amounts of Heterogenous and Homogenous (mainly dammar) Unstructured OM, moderate amounts of Structured OM and Finely Dispersed Unstructured OM, and low amounts of Black Indeterminate OM, is restricted to depositional sites that are principally found in freshwater settings. The second assemblage, characterized by the highest quantities of Heterogenous and Indeterminate Black and the least amount of Finely Dispersed Unstructured OM, is found in channels of the lower delta plain. The distribution of this palynofacies assemblage conforms to the limit of saline influence during the wet season. The third group, characterized by the highest quantitative amount of Finely Dispersed Unstructured OM, is found either in barforms or in black-water tidal channels that are sediment starved. These results indicate that OM assemblages preserved in a single sediment facies characteristic of transitional zones may vary in response to the abiotic processes operating within the system.
Shell beds pose questions of provenance, but determining the degree of pre-depositional transport of bioclasts can be speculative. Bioclastic beds deposited on a broad, shallow continental shelf may consist of a minimally transported accumulation. In contrast, islands may have steep shelves and accumulate disharmonious bioclastic assemblages in deeper water. The latter are a signature of the stratigraphic record on many islands. Herein, we contrast differing examples of jumbled shell beds preserved around islands. The Lower Permian Mengkarang Formation of Sumatra preserves deep-water facies at the base of a volcanic section. Nektonic cephalopods overlie a fine-grained ash containing a diverse association of terrestrial pollen. The Lower Miocene Montpelier Formation of Jamaica yields allochthonous packstones and slide blocks of reef limestone embedded in chalk; the ichthyofauna indicates deposition in >= 200 m water depth. Abundant evidence that deposition occurred in a deep-water turbidite basin flanking a volcanic island is found in the Middle Miocene Grand Bay Formation of Carriacou, the Grenadines. Diverse, deeper water taxa are preserved in association with land snails, hermatypic scleractinians, algal balls and planktic pteropods. The famous Upper Pliocene Bowden shell beds, Jamaica, preserve terrestrial, shallow-water, deep-water and planktic taxa.
The Mahakam Delta is a tropical, fluvio‐tidally dominated delta prograding onto a mixed siliciclastic‐carbonate shelf. Surface sediments were collected from 12 distinctive depositional environments extending from the head of the Mahakam Delta to the shelf edge. Organic matter was extracted from 200 samples by acid digestion, and seven palynomorph types (pollen, embryophyte spores, fungal spores, foraminiferal linings, copepod eggs, tintinnomorphs, and dinocysts) were identified and counted, and their percentages and concentrations calculated. Total organic carbon (TOC), lithology, and depositional environments were recorded for each sediment sample. The amounts of terrestrial palynomorphs in sediments can be explained by transport and depositional processes, and four groups of environments are identified (tidally influenced, detrital peat beach, lowland rain forest, and marine shelf)‐ Because of tidal flushing of the delta plain, pollen, embryophyte spores, fungal spores and soft plant debris from the soil litter are deposited together with clastic mud at slack‐water periods. As a result, all tidally‐influenced environments exhibit constant numbers of pollen, embryophyte spores, and fungal spores per unit of TOC. In lowland rain forest sediments, there is minor clastic dilution and the numbers of pollen and spores are three to 10 times higher per unit TOC than in tidally‐influenced sediments. In detrital peat beach and marine shelf sediments, the number of sporomorphs per unit TOC is lower than expected because of the selective removal of sporomorph‐sized particles by wave action and of dilution with autochthonous marine organic matter respectively.In contrast, the amounts of marine palynomorphs in sediments are related to the depositional environments. Relative amounts of marine palynomorphs increase gradually offshore, as both the sporomorph percentages and concentrations decrease simultaneously. Once in fully marine conditions, concentrations of marine palynomorphs are comparable in all shelf environments. The marine assemblages are mainly represented by Zooplankton (copepod eggs) and benthic protists (foraminiferal linings), the phytoplanktonic constituent (dinocyst) playing a subordinate role.
An actualistic investigation has been conducted on palynofacies recovered from a limited sample set of water column and grab samples in freshwater fluvial, brackish water fluvial, and estuary mouth (kuala) environments of the Rajang River and delta, Sarawak, East Malaysia. Palynofacies are overwhelmingly dominated by Unstructured Organic Matter (OM), with varying amounts of Structured OM, Palynological OM, and an insignificant amount of Indeterminate OM (black opaques). Non‐parametric statistical analyses (Chi‐Square and Mann‐Whitney rank sum) were conducted to determine if different physical processes operating in the delta (tidal range, time of sample collection, water chemistry, and depositional setting) affected assemblage composition. Palynofacies assemblages were evaluated using UPGA clustering techniques to determine if distributional patterns existed in the study area.
No statistical relationship was found between the OM particle category and sediment‐grain size within the delta. In general, assemblages from water‐column samples recovered from freshwater sites have significantly higher proportion of Unstructured OM than do assemblages from saltwater influenced sites. A similar distribution is seen in grab samples, except that river channels active during the dry season possess the same palynofacies assemblages at the sediment‐water interface and differ from abandoned, tidally flushed channels. The abandoned channels have higher proportions of Structured OM both in the water column and at the sediment‐water interface than do OM assemblages from freshwater collection sites. There is no 1:1 relationship between the OM assemblages found in the water column, at the sediment‐water interface, and sediment recovered from the subsurface (using vibracores) from the same generalized collection area. Early diagenetic alteration in sites influenced by marine waters alters the character of the acid‐resistant organic constituents with the production of Black Opaque Indeterminates, resulting in a different acid‐resistant organic assemblage.
Sediment samples from the Banda Sea were clustered according to the percentages of the different morphotypes of copepod egg-envelopes they contained. The clustering indicates a geographically distinct cluster determined by the occurrence of higher percentages of a single type of copepod egg envelope. It may be indicative of the influence of Equatorial Indian Ocean surface water, notably in the southwestern part of the Banda Sea that is not affected by upwelling.
Palynological analysis of box-core samples from surficial deep-sea sediments along three transects in the Banda Sea (Indonesia), demonstrates that associations of palynomorphs, palynodebris and diffuse organic aggregates are mainly composed of terrigenous and zooplanktonic constituents. Organic remains of phytoplankton and benthos play a subordinate role in this area. The presence of surprisingly high proportions of notably egg-envelopes and exoskeleton fragments of copepods indicates that areas with seasonally enhanced high productivity can serve as an important sink of organic carbon derived from primary consumers. These zooplankton remains, as well as a considerable part of the terrigenous organic matter originate from animal and plant tissues that are chemically characterized by a high polysaccharide (chitin, cellulose) content. The quantitative prominence of such labile components can be explained by high organic matter influx in combination with high sedimentation rates in the area. Considering the positive relationship between organic matter preservability and sedimentation rate, variations in the amount of transparent palynodebris derived from crustacean exoskeletons may serve as a proxy indicatpr for spatical variations in organic carbon burial efficiency in surficial sediments. It is emphasized that occurrences of structurally preserved organic matter with a presumed chitinous and cellulosic composition are not restricted to young sediments. For reasons not yet fully understood, some structures may even remain preserved under conditions of thermal maturation, so that their records may go well back into the Palaeozoic.
Four species of a new fossil microspore genus are described. Their resemblance to certain extra-Australian fossil and living microspores is noted.
The standard textbook of Vegetation Ecology. A reprint (2002) is available from The Blackburn Press, Caldwell, New Jersey.
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