Search

The eastern Kendeng Hills (Java, Indonesia) expose a 1000 m thick series that is used as a stratigraphic standard, representing the emergence of eastern Java from the sea. The fluvial top is rich in vertebrate fossils and yielded the Mojokerto (Perning) hominin skullcap, which is regarded as the earliest evidence of Homo erectus on Java, with age estimates ranging between 1.9 and 1.49 Ma. The series is commonly regarded as an uninterrupted record of coastal progradation. However, recent studies show that the emergence of eastern Java has been a complex process, under influence of tectonism, volcanism, sea-level fluctuations and fluvial dynamics, leaving a fragmented depositional record that varies from site to site. This is at odds with the prevailing stratigraphic practice of long-distance correlations and questions the existing interpretations of the eastern Kendeng reference sections. Here we present the results of a fieldwork-based re-interpretation of this key stratigraphic record, which we identified as the fill of a previously unrecognized Plio-Pleistocene embayment, surrounded by elongate uplift zones. Clinoform-bedded sandstones relate to a stage of explosive, high-silica volcanism, supplying large volumes of ash. The embayment fill is incised and covered by fluvial deposits, which we relate to the Middle Pleistocene Brantas. The fluvial strata have a cyclic build-up, probably representing sea-level controlled stages of aggradation and degradation. Based on a reconstruction of fluvial cycles, we provisionally link the conglomerate bed in which the Mojokerto Homo erectus was found to MIS14 (similar to 550ka). We infer that the published radiometric ages derive from reworked volcanic clasts that make up this incisive fluvial lag and are not representative for the age of deposition. Our study places the eastern Kendeng series in a new landscape context and changes our view of the timing of hominin migration to Java. (C) 2022 Published by Elsevier Ltd.

In a previous presentation at the Messinian Seminar 3 (Malaga, 1977), Geerlings described the distribution of planktonic foraminifera in the Los Perales section of the Sorbas basin. The same section has now been analysed quantitatively for its benthonic foraminifera content, to serve as a standard for our investigations in the adjoining basins. The preliminary results of a paleoecological analysis are discussed in relation to the lithological facies development. Various explanations can be offered for the faunal and lithological changes in the latest Miocene : change in salinity, change in depth, change in temperature. It seems most likely, that all three factors mentioned were effective ; an increased salinity in a shallowing basin, possibly accompanied by a pronounced cooling, set on during deposition of the upper part of the studied interval. Initial investigations in neighbouring basins (Vera, Campo de Nijar) seem to indicate, that comparable trends are present over a wider area., Au 3° Séminaire sur le Messinien (Malaga, 1977), Geerlings a présenté la distribution des foraminifères planctoniques dans la coupe de Los Perales située dans le bassin de Sorbas. Une étude quantitative de la microfaune benthique de cette coupe a été réalisée maintenant pour servir de standard pour nos recherches dans les bassins voisins. Les résultats préliminaires de l'analyse paléoécologique et leurs relations avec la lithologie sont discutés. Plusieurs explications peuvent être proposées pour les changements lithologiques et faunistiques intervenant à la fin du Miocène : variations de salinité, de profondeur ou de température ; ces trois facteurs ont vraisemblablement joué un role effectif ; un accroissement de la salinité dans un bassin dont la profondeur diminue, peut-être accompagné d'un refroidissement, est intervenu pendant le dépôt de la partie supérieure de l'intervalle considéré. Des recherches préliminaires dans les bassins voisins (Vera, Campo de Nijar) semblent indiquer que ces phénomènes ont une extension géographique plus importante., Troelstra S.R., Van Der Poel H.M., Huisman C.H.A., Geerlings L.P., Dronkert Hans. Paleoecological changes in the latest Miocene of Sorbas basin, S.E. Spain. In: Géologie Méditerranéenne. Tome 7, numéro 1, 1980. Aspects dynamiques du passage Miocène – Pliocène en Méditerranée. pp. 115-125.

A boxcore taken from the top of a seamount south of Crete, on the outer (south) side of the Hellenic Trench, contains allochtonous coarse clastics, consisting mainly of rock fragments of alpine basement, brecciated Early/Middle Pliocene marls and reworked older Neogene sediments. This mixture of lithologies is interpreted as an Early/Middle Pliocene mass-flow deposit, which can be correlated with similar deposits from adjoining on- and offshore areas. The wide distribution of these sediments may be related to a period of increased tectonic activity which caused substantial vertical movements in the south Hellenic Arc. It is concluded that at the time of the formation of the mass-flow deposits this part of the Hellenic Trench had not yet evolved.

This paper summarizes micropaleontologic (foraminifera, calcareous nannoplankton, radiolaria, pteropods and pollen grains) and sedimentologic piston core data from the Eastern Mediterranean Tyro and Kretheus basins. 14 C datings indicate a Holocene age for the Tyro Basin cores. The latter show anoxic bottom conditions throughout, while the Kretheus Basin core indicates anoxic conditions prior to 3000 years ago and oxic conditions after that time. Resedimentation — through slumps, turbidity currents and from suspension — resulted in high sediment accumulation rates in both basins. Reworking in the Tyro Basin predominantly originated from the basin flanks, while the presence of common to abundant metamorphic clastics in the Kretheus Basin points to a more distant source. The Minoan eruption of Santorini (ca.3350 yrs B.P.) which is supposed to have caused a gigantic tsunami, is linked to the presence of turbidites and a thick homogenite in the Tyro Basin. The same event may be responsible for the initiation of oxic conditions in the Kretheus Basin.

Paleoclimate changes are reconstructed from Late Miocene-earliest Pleistocene deep-water sediments of the Solo River section, using fluctuations in planktonic foraminiferal faunas, water depth and clastic influx. Intervals with common cold-water planktonics (Globigerina bulloides, Neogloboquadrina cf. pachyderma) are thought to reflect periods of increased upwelling, triggered by Antarctic glaciations. Correlations with well Bodjonegoro-1 (Java), DSDP Site 62-1 and Lamont Core RC 12–66 (Equatorial Pacific) using planktonic foraminiferal datum levels and paleoclimate trends suggest non-synchroneity of several commonly used datums, probably due to differences in species concepts. It also allowed dating of the climate changes with regard to the magnetostratigraphic and numerical time scales. For correlations between different faunal provinces global climate changes are an extremely useful tool, probably superior to any single faunal datum. Using this, with other evidence, the following correlations could be obtained between the five “climatostratigraphic” zones in the Solo River section and the Mediterranean and New Zealand stages (from bottom to top): 1. Zone I, samples SR 63–SR 53, cool, older than 6.0 m.y. – ±5.8 m.y., magnetostratigraphic Epoch 6 (and older?) — basal Epoch 5, planktonic zone (Upper N16?-) N17, Mediterranean stages (upper?) Tortonian—Early Messinian, New Zealand Stages Tongaporutuan—Early Kapitean, Late Miocene. 2. Zone II, SR 52–SR 35, moderately warm with fluctuations, ± 5.8 m.y.–5.0 m.y., Epoch—lowermost Gilbert, upper N17 (−N18?), Late Messinian (evaporite phase), Late Kapitean, Late Miocene. 3. Zone III, SR 34–SR 33, cool, 5.0–4.8 m.y., within Lower Gilbert, (N18?-) basal N19, latest Messinian (“Lago Mare” phase), latest Kapitean or earliest Opoitian, latest Miocene. 4. Zone IV, SR32–SR 18, warm to very warm, 4.8–±2.7 m.y., within Lower Gilbert — within Upperg Gauss, N19 within N21, Zanclean-Piacenzian, Opoitian Pliocene. 5. Zone V, SR17–SR 12, cool, ±2.7 m.y.—age of top unknown, Upper Gauss-Lower Matuyama, within N21 (−N22?), Santernian or basal Calabrian s.l., Waipipian, basal Pleistocene (Late Pliocene of workers with different Pliocene-Pleistocene boundary concepts).