Tectonic implications of new age data for the Meratus Complex of south Kalimantan, Indonesia

Cretaceous subduction complexes surround the southeastern margin of Sundaland in Indonesia. They are widely exposed in several localities, such as Bantimala (South Sulawesi), Karangsambung (Central Java) and Meratus (South Kalimantan).
The Meratus Complex of South Kalimantan consists mainly of mélange, chert, siliceous shale, limestone, basalt, ultramafic rocks and schists. The complex is uncomformably covered with Late Cretaceous sedimentary-volcanic formations, such as the Pitap and Haruyan Formations.
Well-preserved radiolarians were extracted from 14 samples of siliceous sedimentary rocks, and K–Ar age dating was performed on muscovite from 6 samples of schist of the Meratus Complex. The radiolarian assemblage from the chert of the complex is assigned to the early Middle Jurassic to early Late Cretaceous. The K–Ar age data from schist range from 110 Ma to 180 Ma. Three samples from the Pitap Formation, which unconformably covers the Meratus Complex, yield Cretaceous radiolarians of Cenomanian or older.
These chronological data as well as field observation and petrology yield the following constraints on the tectonic setting of the Meratus Complex.
(1) The mélange of the Meratus Complex was caused by the subduction of an oceanic plate covered by radiolarian chert ranging in age from early Middle Jurassic to late Early Cretaceous.
(2) The Haruyan Schist of 110–119 Ma was affected by metamorphism of a high pressure–low temperature type caused by oceanic plate subduction. Some of the protoliths were high alluminous continental cover or margin sediments. Intermediate pressure type metamorphic rocks of 165 and 180 Ma were discovered for the first time along the northern margin of the Haruyan Schist.
(3) The Haruyan Formation, a product of submarine volcanism in an immature island arc setting, is locally contemporaneous with the formation of the mélange of the Meratus Complex.     

Green growth rhetoric versus reality: Insights from Indonesia

By 2030 Indonesia aims to reduce its CO₂ emissions by 29% while maintaining a 7% annual GDP growth rate, thus making “green economy” a reality. Based on a review of literature and secondary data and interviews with key informants, this article examines the gap between these national ambitions and the reality on the ground, with particular attention to the challenges of multi-scalar environmental governance. It first introduces the green economy concept and discusses the main green growth policies and initiatives at the national level. The article then examines green growth ambitions at the provincial level in East Kalimantan province. Our findings suggest that existing plans to further expand oil palm plantations are at odds with provincial efforts to reduce emissions. This highlights a key paradox we identify at the heart of the green economy concept as it is developing in Indonesia: between a development trajectory based on resource extraction and agro-industrial development, and ‘green’ aspirations linked to environmental protection and greenhouse gas emissions reductions. We conclude that the main challenges to address these contradictions are related to the lack of coordination between different governance scales and a political economy that is not conducive to reforms in the land-based sector. There is a need to align investment, planning, and green growth policies, based on a strong political commitment and an awareness of social and environmental trade-offs. On a more general level the article shows that the green economy concept refers to a form of environmental governance in which authorities and interests may overlap and come into conflict at different scales. Hence, differing priorities may lead the material expression of the green economy to diverge significantly from policy as it is initially laid out.     

Impacts of land use and fire on the loss and degradation of lowland forest in 1983–2000 in East Kutai District, East Kalimantan, Indonesia

Deforestation and forest degradation are proceeding rapidly in the lowland forests of Indonesian Borneo. Time series analysis of satellite imagery provides an ideal means of quantifying landscape change and identifying the pathways which lead to the changes. This study investigates the forest and land cover changes by classifying Landsat MSS (Multispectral Scanner), TM (Thematic Mapper) and ETM+ (Enhanced Thematic Mapper Plus) images over three time periods (1983–90, 1990–98, and 1998–2000), creating land cover maps for each year and change trajectories for each year-pair. The study area chosen covers an area of 2160 km² of undulating topography and alluvial plains in the East Kutai District of East Kalimantan Province, which in the 1980s was covered mostly with lowland dipterocarp forest; today the landscape is a patchwork dominated by oil palm and timber plantations and degraded forest. We relate land cover change data to land use allocation and to fire impacts based on fire hotspot distribution and fire damage information. The multidate land cover change trajectories provide an insight into the forest loss and degradation pathways over the 17-year period spanning the first entry of commercial logging concessionaires, followed by a government-sponsored transmigration scheme, government-licensed timber and oil palm plantations and, finally, the devastating fires of 1998. The results show a mean deforestation rate of 42 km² or 6 per cent per year for 1983–2000, rising to 10 per cent per year for 1990–98; by 2000, 70 per cent of forest initially damaged by fire and drought during the 1982–83 El Niño event was classified as non-forest. Although our study area is perhaps a worst-case scenario in terms of land use planning outcomes, the lessons from this research are directly applicable to scenario prediction for informed forest and land use planning and monitoring.     

加里曼丹岛西北侧低盐水季节变化及机理分析

利用LEVITUS温盐资料、HOAPS降水及蒸发资料以及OFES模式资料等分析加里曼丹岛西北侧表层低盐水的季节变化规律,并使用盐度平衡模式诊断了海面淡水通量、径流、卷挟作用以及平流作用对低盐水变化的贡献.分析表明:加里曼丹西北侧全年均存在1个低盐水团,其季节变化具有"双峰"特征,3月至4月以及10月至11月会发生2次低...     

印尼加里曼丹岛东部主要含油气盆地油气富集差异

为加强印尼加里曼丹岛东部地区战略选区研究,指明选区方向,从分析已发现油气分布规律入手,重点探讨了油气分布的控制因素,分析了低勘探程度区勘探潜力。研究表明:(1)陆上和海上分别受控于始新统和中新统三角洲煤系烃源岩,烃源岩类型、成熟度和规模共同控制油气发现"海多陆少、中部为气、南北为油"格局;(2)烃源岩和输导体系是控制油气成藏和分布的两个关键因素,海上和陆上输导体系的差异控制了海陆油气发现,表现为"陆老海新"特征;(3)海上北部达拉根盆地"近源逆冲断裂带"与陆上南部巴里托盆地南部"基底潜山带",石油地质条件优越,勘探潜力较大。     

The Impact of Orographically-Induced Gravity Wave on the Diurnal Cycle of Rainfall over Southeast Kalimantan Island

Precipitation measurements from the Tropical Rainfall Measuring Mission (TRMM) satellite indicate that the southeastern area of Kalimantan (Borneo) Island receives much less rainfall than elsewhere on the island during the period from July to October.Results from sur-face meteorological observations show that the diurnal cycle of rainfall differs greatly between the eastern and western coasts of the island.Rainfall on the western coast of the island is frequent in the afternoon and evening,whereas almost all rainfall on the eastern coast occurs in the morning.Meanwhile,the Global Positioning System (GPS)-derived precipitable water (PW) on the eastern coast shows a substantial decrease in moisture in the af-ternoon and evening.Numerical experiments with a mesoscale model reveal that gravity waves driven by di-urnal heating of the elevated land surface of the moun-tains on Sulawesi Island,which lies approximately 300 kilometers to the east of Kalimantan Island,significantly affect the diurnal cycle of rainfall over southeast Kali-mantan Island.     

Medium resolution imaging spectrometer data for monitoring tropical coastal waters: a case study of Berau estuary,East Kalimantan,Indonesia

This article investigates the performance of MERIS reduced resolution data to monitor water quality parameters in the Berau estuary waters, Indonesia. Total suspended matter (TSM), Chlorophyll-a (Chl-a) concentration and diffuse attenuation coefficient (K_d ) were derived from MERIS data using three different algorithms for coastal waters: standard global processor (MERIS L2), C2R and FUB. The outcomes were compared to in situ measurements collected in 2007. MERIS data processed with C2R gave the best retrieval of Chl-a, while MERIS L2 performed the best for TSM retrieval, but large deviations from in situ data were observed, pointing at inversion problems over these tropical waters for all standard processors. Nevertheless, MERIS can be of use for monitoring equatorial coastal waters like the Berau estuary and reef system. Applying a K_d (490) local algorithm to the MERIS RR data over the study area showed a sufficient good correlation to the in situ measurements (R ² = 0.77).     

Danske provinsbyers indre differentiering og differentieringen mellem danske provinsbyer

Pedersen, P. O. & Rasmussen, P., 1973: Danske provinsbyers indre differentiering og differentieringen mellem danske provinsbyer. Geografisk Tidsskrift, 72, 49–56. København, September 30., 1973.

This paper analyses the inner differentiation in the three largest provincial towns in Denmark by means of a factor analysis of 25 variables characterizing the population and the housing in 40 zones, 14 in Århus (187,000 inh.), 14 in Odense (133,000 inh.), and 12 in Ålborg (123,000 inh.). The paper especially focuses on the differences in inner differentiation between the three towns.     

Cross dating (Th/U-C) of calcite covering prehistoric paintings in Borneo

We present the first application of cross-dating (Th/U measured by thermo-ionization mass spectrometry (TIMS) and ¹⁴C measured by accelerator mass spectrometry (AMS)) of calcite covering prehistoric paintings. Th/U age estimates of cave drapery range from 9800 to 27,300 yr B.P. while conventional ¹⁴C age is estimated between 9900 and 7610 yr B.P. depending on the dead carbon correction. The age discrepancy is attributed to a disturbance of Th/U and/or ¹⁴C geochemical systems, showing the limits of the geochronological approach applied to this kind of material. For the Th/U system, the poor consistency of U data (U content, ²³⁴U/²³⁸U activity ratios) and apparent ages argue for open system conditions. For ¹⁴C system, variation of the dead carbon fraction (dcf) and a possible mixing of successive generations of calcite could account for age discrepancy. Nevertheless, one sample shows concordant ages for the two methods. Compatible ages through corrections for open system conditions are assumed for other samples. Then, the cross-dating suggests 9900 yr as the minimum age of the piece of drapery; the underlying painting must be older. This study of rock art demonstrates the presence of a Pleistocene population before 9900 yr in the southeast of Borneo, whereas previously the only population in evidence in this area was of Austronesian type from ∼5000 to 6000 yrs ago.     

东南亚加里曼丹新生代金成矿作用及成矿动力学

对加里曼丹岛区域地质背景、金成矿作用与新生代岩浆弧关系研究认为,该区浅成低温热液金矿床与新生代岩浆弧内晚渐新世—中中新世钙碱性岩浆活动存在着密切的时空及成因联系。其动力学机制为,始新世—中新世期间印度—澳大利亚板块向欧亚板块俯冲引起的地幔物质向南东方向的流动导致早渐新世亚洲边缘发生裂解,裂解作用又导致南中国海板块向加里曼丹岛北缘俯冲。俯冲过程中加里曼丹岛北缘在晚渐新世—中中新世发生大规模的构造岩浆活动及浅成低温热液金成矿作用。成岩成矿作用是在总体挤压背景体制下的局部拉张环境下进行的。