Showing papers by "Indonesian Institute of Sciences published in 1994"

Quaternary uplifted coral reef terraces on Alor Island, East Indonesia

Abstract: A flight of six major coral reef terraces, up to 700 m in altitude, occurs along the eastern and northern sides of Kabola Peninsula, Alor Island, Indonesia. Some radiometric dates have been obtained from unrecrystallized coral samples collected in growth position by three different methods (14C, 230Th/234U, ESR). This enabled the identification of the terraces corresponding to the Holocene and to oxygen-isotope stages 5c, 5e and 7. According to the present elevation of the dated terraces, a 1.0–1.2 mm/y mean rate of uplift can be discerned. Extrapolation of this trend to the whole sequence of terraces reveals a good correlation between the development of major terraces and interglacial or interstadial stages corresponding to astronomically calibrated oxygen isotope records, up to stage 13. The relatively rapid uplift rate in this region minimized the possibility of polycyclic sea-level stands at the same levels and contributed to the good preservation of some morphological reef features. Two superimposed marine notches are visible near the present shoreline, with retreat points at about 5.0 m and 8.6 m respectively above the present MLWST level. They can be interpreted as corresponding to a glacial interstadial (the upper notch) and to the Holocene sea-level peak (the lower one). As Holocene emergence has been less than what could be expected from a 1 mm/y rate of uplift, a major coseismic vertical displacement may occur in the future.

Low frequency variability of the currents in Indonesian channels (Savu-Roti and Roti-Ashmore Reef)

Abstract: Direct current measurements of one year duration were obtained in two Indonesian channels, between Savu and Roti and in the Timor Passage. Their analysis, together with data from Indonesian coastal tide gauges, supports the rather high value of transport deduced from geostrophic calculations across the hydrographic section made in August 1989. At that time, the Timor Passage may have fed more than half of the throughflow. A strong variability was observed in the form of sudden changes in the current regime with amplitude of the same order as the seasonal one. Observations indicate the importance of sea level measurements along the Indonesian coast, which show some correlation with the flow through the Timor Passage.

Measurements within the Pacific-Indian oceans throughflow region

Abstract: Two hydrographic (θ, S, O2) and trichlorofluoromethane (F-11) sections were carried out between the Australian continental shelf and Indonesia, in August 1989, on board the R.V. Marion Dufresne. The sections lie in the easternmost part of the Indian Ocean where the throughflow between the Pacific Ocean and the Indian Ocean emerges. They allow us to describe the features of the water-property and circulation fields of the throughflow at its entrance in the Indian Ocean. Between the Australian continental shelf and Bali, the Subtropical and Central waters are separated from the waters of the Indonesian seas by a sharp hydrological front, located around 13°30 S, below the thermocline down to 700 m. Near the coast of Bali, upwelling occurs in the near-surface layer under the effect of the southeast monsoon; at depth, between 300 m to more than 800 m, a water mass of northern Indian Ocean origin was present. From the characteristics of the bottom water found in the Lombok basin, the maximum depth of the Java ridge which separates the Lombok basin from the Northwest Australian basin lies around 3650 m. Off Sumba, Savu, Roti and Timor channels a core of low salinity and high oxygen content near-surface water was found in the axis of each channel, which suggests strong currents from the interior Indonesian seas towards the Indian Ocean. The entrance of the deep water flowing in the opposite direction, from the Indian Ocean to the Timor basin, was marked below 1400 m to the sill depth, through an increase of salinity and oxygen content. The flow reversal, observed briefly by a Pegasus direct current profiler in the Timor strait, was located at 1200 m depth. During the southeast monsoon, the net (geostrophic + Ekman) transport calculated on the section Australia-Bali give an estimate of the throughflow between 0 and 500 m of 22 ± 4 × 106 m3 s−1 towards the Indian Ocean, with a concentration of the transport in the upper layers (19 × 106 m3 s−1 in 0–200 m) and near the Indonesian coast, north of 13°30 S. In this region of intense mixing, attempts to make a salinity budget were inconclusive but did not imply any reduction in estimated throughflow transport. Below 500 m the net transport is of the order of the uncertainty. The total estimated transport (0–1900 dbar, deepest sill depth) is 18.6 × 106 m3 s−1 (±7) with a mean temperature of 23°C and a mean salinity of 34.0 psu (but may be as large as 23 × 106 m3 s−1, with mean temperature of 20°C and mean salinity of 34.1 psu).

An enriched soft systems methodology (SSM) and its application to cultural conflict under a paternalistic value system

Abstract: A modification of soft systems methodology (SSM) especially suitable for tackling problematic situations under the Eastern cultural influence is proposed. It emerged when we tried to apply SSM to a cultural conflict problem caused by the introduction of new technologies into an R&D institute in Indonesia. Our modification, the main constituent of which is the replacement of the debate stage by what we call indirect debate, is inevitable for dealing with this problem to satisfy the kernel of SSM, since the philosophy of SSM requires communicative competence. We believe that our modified SSM, combined with the descriptive analysis of Davies and with the cultural analysis of Checkland and Scholes, provides a powerful way of improving problematic situations where Eastern cultural factors play dominant roles.

GEOGRAPHIC AND SEX DIFFERENCES IN POSlTIONAL BEHAVIOR OF ORANG-UTANS

Abstract: The basic aim of this paper is to present a synthesis of the field work that we have been conducting on the positional behavior of orang-utans. The data have been collected from two study sites, of which one was at Ketambe, Gunung Leuser National Park, northern Sumatra and the other at Mentoko, Kutai National Park, eastern Kalimantan. We attempt to interpret positional behavior in an ecological context, and we evaluate several hypotheses, some of which can not be tested conclusively at the present time.

Observation on the avifauna of siberut island, 1992-1994

Abstract: The recent studies were carried out in 1992-1994, and aimed at investigating recent status and distribution of the avifauna of Siberut Island. Ninety-six species were recorded during the observations, of which all endemic subspecies and one endemic species were observed. From all species, 11.5% were very common and 37.5% were common in the island, while 28.1 % of them were uncommon and22.9% were rarely found. Protected and endemic species were amongt the rarely found birds, except the nectar feeding birds which were abundant in the island. Most of these birds might have functioned as either secondary or tertiary consumers, which are vulnerable to habitat deterioration. Habitat conservation may be the best measures to be considered.

A study on the cementation of gold from thiourea leach liquors of cimanggu-type gold ore

Abstract: As an alternative hydrometallurgical route, the gold ore from Cimanggu was leached in solutions containing thiourea and sulphuric acid with and without the addition of sodium bisulphite. In order to recover gold from the leach solutions, cementation with zinc, lead and aluminium powders was studied. The study reveals that recovery of cemented gold increases with stirring rate, metal loading and temperature, and is dependent on type of metal and leaching parameters. The use of lead as a cementant is advantageous in terms of gold recovery and metal consumption. Optimum recovery (about 50%) is obtained from a leach liquor produced by a leaching solution containing 10 g/l thiourea, 4.9 g/l sulphuric acid and without the addition of sodium bisulphite. Gold cementation with Zn/Pb is predicted to be diffusion controlled behaviour.