Studi Awal Geologi di Daerah Beruang Kanan Kabupaten Gunung Mas Propinsi Kalimantan Tengah

The regional tectonic conditions of the KSK Contract of Work are located in the mid-Tertiary magmatic arc (Carlile and Mitchell, 1994) which host a number of epithermal gold deposits (eg, Kelian, Indon, Muro) and significant prospects such as Muyup, Masupa Ria, Gunung Mas and Mirah. Copper-gold mineralization in the KSK Contract of Work is associated with a number of intrusions that have occupied the shallow-scale crust at the Mesozoic metamorphic intercellular junction to the south and continuously into the Lower Tertiary sediment toward the water. This intrusion is interpreted to be part of the Oligocene arc of Central Kalimantan (in Carlile and Mitchell 1994) Volcanic rocks and associated volcanoes are older than intrusions, possibly aged Cretaceous and exposed together with all three contacts (Carlile and Mitchell, 1994) some researchers contribute details about the geological and mineralogical background, and some papers for that are published for the Beruang Kanan region and beyond but no one can confirm the genesis type of the Beruang Kanan region The mineralization of the Beruang Kanan area is generally composed by high yields of epithermal sulphide mineralization. with Cu-Au mineralization This high epithermal sulphide deposition coats the upper part of the Cu-Au porphyry precipitate associated with mineralization processes that are generally controlled by the structure

Karakteristik Hidrolika Batuan Sedimen Tersier Berdasarkan Analisis Uji Pemompaan di Kabupaten Cilacap dan Banyumas, Provinsi Jawa Tengah

ABSTRAKSebagian wilayah Kabupaten Cilacap dan Banyumas memiliki tipologi akuifer sedimen terlipat yang tersusun atasbatuan berumur Tersier Formasi Halang, Kumbang, dan Tapak. Penelitian ini dilakukan untuk mengetahui karakteristikhidrolika dan potensi air tanah batuan tersebut berdasarkan analisis uji pemompaan sumur bor air tanah. Hasil analisismenunjukkan batuan tersebut memiliki karakter akuifer semitertekan hingga tertekan. Nilai konduktivitas hidrolikadan permebilitas intrinsik menunjukkan batuan tersebut relatif bersifat sebagai akuifer dengan karakter hidrolika samadengan lanau, lanau pasiran, dan pasir lempungan. Kuantitas air tanah berdasarkan transmisivitas akuifer menunjukkanpotensi jelek hingga sedang untuk kebutuhan domestik, dan potensi sangat jelek untuk kebutuhan irigasi. Nilaikapasitas jenis sumur bor menunjukkan pemompaan dengan debit 1 hingga 2 l/det. masih bisa diharapkan.Kata kunci: karakteristik hidrolika, air tanah, sedimen tersier, uji pemompaanABSTRACTParts of the Cilacap and Banyumas Regencies have folded sedimentary aquifer typology that consist of TertiarySediment of Halang, Kumbang, and Tapak Formations. This study was conducted to determine the hydrauliccharacteristics and groundwater potential of these rocks based on a pumping test analysis. The analysis shows therocks have confined and semiconfined aquifer characters. Based on rock hydraulic conductivity and permeabilityvalues, the aquifer has similar character to silt, sandy silt, and silty sand. Groundwater quantity, based on aquifertransmissivity, indicates poor to moderate for domestic need and insufficient for irrigation purpose. The specificcapacity value shows that pumping rate of 1 to 2 l/sec. can be expected.Keywords: hydraulic characteristics, groundwater, tertiary sediment, pumping test

STRUKTUR DIAPIR BAWAH PERMUKAAN DASAR LAUT DI KAWASAN PESISIR SELATAN KABUPATEN SAMPANG-PAMEKASAN, JAWA TIMUR

Penelitian seismik pantul dangkal saluran tunggal (seismic profiling) dilakukan di lepas pantai Kabupaten Sampang dan Pamekasan, pesisir selatan Madura dengan hasil rekaman sepanjang 300 km. Interpretasi data seismik dilakukan dengan cara memisahkan runtunan-runtunan yang diduga mempunyai karakter yang berbeda serta mencirikan urut-urutan pengendapan batuan sedimen. Ciri dari runtunan Kuarter ditandai dengan sedimen yang mempunyai runtunan yang tidak terganggu oleh aktivitas struktur geologi seperti perlipatan maupun pensesaran. Runtunan Tersier dicirikan dengan adanya aktivitas struktur lipatan sangat ketat seperti antiklin, sinklin, dibarengi dengan sesar-sesar, serta intrusi-intrusi diapir. Data interpretasi seismik pantul dangkal saluran tunggal memberikan gambaran tentang struktur geologi bawah dasar laut walaupun dengan penetrasi yang sangat terbatas (dangkal). Data tersebut juga memberikan gambaran serta indikasi adanya jebakan-jebakan gas bumi dan diapir di kawasan pantai Kabupaten Pemekasan dan Sampang. Kata Kunci : seismik, runtunan, diapir, Sampang dan Pamekasan Single channel seismic profiling activity carried out in the southern coast of Pamekasan and Sampang District, southern coast of Madura, has recorded data of more or less 300 kilometres. The interpretation of seismic profiling records have been done by separating the sequence of sediments which have chronologically different character and depositional environments. The characteristic of Quaternary sediment sequence is indicated by the sediment that did not disturbed by geological structures, such as folding and faulting. The Tertiary sediment sequences in the south coast of Pamekasan area have been tightly folded which consist of anticline, sincline shale diapir and faulting phenomena. The interpretation of seismic profiling data showed the indication of the geological structure under the sea floor although by means of the shallow penetration energy. It still can be helpful to indicate diapire and gas closures in the southern coast of Sampang and Pamekasan areas. Key words : seismic, sequence, diapire, Sampang and Pamekasan

Stratigraphy and Paleoecology of Quaternary Sediments Along Pasley River, Boothia Peninsula, Central Canadian Arctic

ABSTRACT Quaternary sediments exposed along Pasley River consist of a lower marine deltaic sand overlain in succession by complexly interbedded tills and glaciomarine sediments (the lower glacigenic assemblage), by a mid-section fluvial gravel, by an upper marine deltaic sand, and by glaciomarine sediment and till (the upper glacigenic assemblage). The midsection fluvial gravels contain plant and insect fossils indicating a climate as warm as and perhaps warmer than present. The top of the gravel is more than 55 000 years old ; the unit is probably of Sangamonian age (>75 000 ka) and separates Wisconsinan from lllinoian glacial deposits. The deltaic sands that underlie both glacigenic assemblages indicate substantial crustal depression during glacial buildup episodes prior to arrival of ice at the site. This implies that the process of buildup was slow and involved glacier expansion into major marine basins. Glaciomarine beds of the lower glacigenic assemblage locally contain abundant detrital terrestrial organic material as well as marine molluscs. The terrestrial organic detritus, an unusual constituent of glaciomarine sediment, is thought to have been released into the sea from glacier ice. These terrestrial fossil asemblages exhibit compositional differences which vary with the sediment faciès and probably reflect taphonomic factors such as differential buoyancy of the fossils. The upper marine deltaic sands contain some "old " rebedded plant detritus and amber indicating a nearby source of Tertiary sediment, possibly equivalent in age to the Beaufort Formation. Other rebedded fossils from the upper deltaic unit may be the same age as the mid-section fluvial gravels.

Microanalysis (Micro-XRF, Micro-XANES, and Micro-XRD) of a Tertiary Sediment Using Microfocused Synchrotron Radiation

Micro-focused synchrotron radiation techniques to investigate actinide elements in geological samples are becoming an increasingly used tool in nuclear waste disposal research. In this article, results using μ-focus techniques are presented from a bore core section of a U-rich tertiary sediment collected from Ruprechtov, Czech Republic, a natural analog to nuclear waste repository scenarios in deep geological formations. Different methods are applied to obtain various, complementary information. Elemental and element chemical state distributions are obtained from μ-XRF measurements, oxidation states of As determined from μ-XANES, and the crystalline structure of selected regions are studied by means of μ-XRD. We find that preparation of the thin section created an As oxidation state artifact; it apparently changed the As valence in some regions of the sample. Results support our previously proposed hypothesis of the mechanism for U-enrichment in the sediment. AsFeS coating on framboid Fe nodules in the sediment reduced mobile groundwater-dissolved U(VI) to less-soluble U(IV), thereby immobilizing the uranium in the sediment.