Interpretation problems of LA-ICP-MS U-Pb geochronology

The existing practice for characterizing the time of a metamorphic event by the average mean of radiogenic mineral dates gives a false idea about the event duration. In the present communication this practice is discussed from the viewpoint of regional geology and geodynamics. Conclusions about the interpretations of radioactive mineral dates for the mineral event duration and the metamorphic event duration are also made.

Peran Kontaminasi Kerak pada Diferensiasi Magma Pembentuk Batuan Vulkanik Sungai Ampalas, Mamuju, Sulawesi Barat

ABSTRAK Anomali radiometri telah ditemukan di area Sungai Amplas pada bongkah batuan vulkanik. Nilai yang terukur dari spektrometer gama adalah 787 ppm eU dan 223 ppm eTh. Penemuan ini menarik untuk pengembangan eksplorasi. Studi lebih lanjut diperlukan untuk mengetahui karekteristik batuan pembawa mineral radioaktif dari sampel in-situ. Penelitian ini bertujuan untuk mengetahui karakteristik petrologi dan geokimia batuan vulkanik Ampalas sebagai studi awal untuk mengetahui proses akumulasi mineral radioaktif pada batuan vulkanik Ampalas. Metodologi yang digunakan meliputi pengamatan lapangan, pengambilan sampel batuan, analisis petrografi dan X-Ray Fluorescence (XRF). Batuan vulkanik ampalas tersusun atas ponolit, foidit, dan foid-syenit. Tekstur batuannya terdiri dari porfiritik, aliran, rim piroksen, zoning, pseudo-leusit, korosi, inklusi mafik, dan sieve. Karakteristik geokimia menunjukkan alkalinitas tinggi dan indikasi pengayaan mineral radioaktif yang tersebar dalam batuan. Proses magmatis yang berperan dalam pembentukan batuan vulkanik adalah fraksionasi kristal (fraksionasi leusit dan alkali felspar), asimilasi kerak kontinen, dan pencampuran magma. Interaksi antara magma dan kerak menyebabkan diferensiasi magma berkelanjutan yang menghasilkan akumulasi uranium dan torium lebih tinggi.ABSTRACT Anomalous radiometry has been found in Ampalas River Area on volcanic rock boulder. The values measured from gamma spectrometer are 787 ppm eU and 223 ppm eTh. This discovery is promising for exploration development. Further study need to figure the radioactive mineral bearing rock characteristic from in-situ samples. The research aim is to determine the petrology and geochemical characteristics of Ampalas volcanic rocks as preliminary study to find radioactive mineral accumulation process of Ampalas volcanic rocks. The methodologies are field observation, rock sampling, petrography, and X-Ray fluorescence (XRF) analyses. The Ampalas volcanic rocks consist of phonolite, phoidite, and phoid syenite. Their textures are porphyritic, flow, pyroxene rim, zoning, pseudo-leucite, corrosion, mafic inclusions, and sieve. The geochemical characteristics show high alkalinity and radioactive mineral enrichment disseminating on rock. The magmatic processes which play a significant role in radioactive mineral-bearing rocks formation are crystal fractionations (leucite and alkaline feldspar fractionations), continental crust assimilation, and magma mixing. Long interaction between magma and crust creates advanced magma differentiation causing higher uranium and thorium accumulation.

Study using Vetiver grass to treat radioacitve pollution at Sin Quyen copper miner area, Lao Cai Province

The article introduces the research results of using Vetiver grass in radioactive environment treatment (water waste, mud waste) in Sin Quyen copper mine area, Lao Cai province. After 30 days, uranium absorption efficiency reached 77.4% and thorium 83.5%, the total alpha and beta activity of the water dramatically declined, alpha treatment efficiency reached 95.3% while beta treatment efficiency reached 93.7%. The model of radioactive pollution treatment by Vetiver showed high efficiency, simple operation. Therefore, it is very promising to apply the treatment of radioactive sludge, radioactive waste sludge in the process of exploiting and processing Sin Quyen copper ore in particular, the areas of radioactive mineral mining in general.

Experimental evidence for the role of natural radioactivity in influencing viability of commensal microorganisms

The role of natural radioactivity in influencing viability of commensal microorganisms, with particular reference to those pertaining to the human microbiota, has not been investigated in detail. The results of experiments culturing a diversified array of microorganims - probiotics - in naturally radioactive mineral water or deuterium-depleted water are here described. Culturing microorganisms in naturally radioactive mineral water yielded one order of magnitude more live microbial cells in comparison with culturing in deuterium-depleted water. Based on these experimental results, a method for co-culturing prebiotic microorganisms (cyanobacteria) that are extremely resistant to the harmful effects of radiations, together with the probiotics mentioned above, is described. The goal of this co-culture in naturally radioactive mineral water is to transfer the information from the radiation-resistant microorganisms to the probiotics whose viability is enhanced by natural radioactivity. Expression of DNA repair genes in cyanobacteria is induced by co-culturing in a medium of carbonated mineral water naturally containing the radioactive isotopes 228U and 226Ra. The culture medium, in addition to naturally radioactive water, contains silica from vegetal origin to enhance horizontal gene transfer. Finally, it is described the transfer of resistance to the harmful effects of radiations to human cells through a Lactococcus phage-encoded protein, ORF252, that is the evolutionary precursor of human proteins involved in DNA repair and cancer protection.

The Crystallinity of Apatite in Contact with Metamict Pyrochlore from the Silver Crater Mine, ON, Canada

The purpose of this work is to evaluate the long-term effects of radiation on the structure of naturally occurring apatite in the hope of assessing its potential for use as a solid nuclear waste form for actinide sequestration over geologically relevant timescales. When a crystal is exposed to radioactivity from unstable constituent atoms undergoing decay, the crystal’s structure may become damaged. Crystalline materials rendered partially or wholly amorphous in this way are deemed “partially metamict” or “metamict” respectively. Intimate proximity of a non-radioactive mineral to a radioactive one may also cause damage in the former, evident, for example, in pleochroic haloes surrounding zircon inclusions in micas. Radiation damage may be repaired through the process of annealing. Experimental evidence suggests that apatite may anneal during alpha particle bombardment (termed “self-annealing”), which, combined with a low solubility in aqueous fluids and propensity to incorporate actinide elements, makes this mineral a promising phase for nuclear waste storage. Apatite evaluated in this study occurs in a Grenville-aged crustal carbonatite at the Silver Crater Mine in direct contact with U-bearing pyrochlore (var. betafite)—a highly radioactive mineral. Stable isotope analyses of calcite from the carbonatite yield δ18O and δ13C consistent with other similar deposits in the Grenville Province. Although apatite and betafite imaged using cathodoluminescence (CL) show textures indicative of fracture-controlled alteration, Pb isotope analyses of betafite from the Silver Crater Mine reported in previous work are consistent with a model of long term Pb loss from diffusion, suggesting the alteration was not recent. Thus, it is interpreted that these minerals remained juxtaposed with no further metamorphic overprint for ≈1.0 Ga, and therefore provide an ideal opportunity to study the effects of natural, actinide-sourced radiation on the apatite structure over long timescales. Through broad and focused X-ray beam analyses and electron backscatter diffraction (EBSD) mapping, the pyrochlore is shown to be completely metamict—exhibiting no discernible diffraction associated with crystallinity. Meanwhile, apatite evaluated with these methods is confirmed to be highly crystalline with no detectable radiation damage. However, the depth of α-decay damage is not well-understood, with reported depths ranging from tens of microns to just a few nanometers. EBSD, a surface sensitive technique, was therefore used to evaluate the crystallinity of apatite surfaces which had been in direct contact with radioactive pyrochlore, and the entire volume of small apatite crystals whose cores may have received significant radiation doses. The EBSD results demonstrate that apatite remains crystalline, as derived from sharp and correctly-indexed Kikuchi patterns, even on surfaces in direct contact with a highly radioactive source for prolonged periods in natural systems.

Studi Keterdapatan Torium Pada Endapan Laterit Bauksit di Pulau Singkep Dalam Rangka Pengembangan Eksplorasi Torium di Wilayah Granit Jalur Timah

Eksplorasi torium di wilayah granit jalur timah pada lima tahun terakhir ditargetkan pada keterdapatan torium di cebakan timah primer maupun sekunder. Pulau Singkep adalah bagian dari Granit Jalur Timah, yang potensial terhadap keberadaan torium, sebagai cebakan primer maupun sekunder. Penelitian ini bertujuan untuk mengetahui karakteristik keterdapatan torium pada laterit bauksit menyangkut kadar torium dan kaitannya dengan keterdapatan mineral radioaktif dan kandungan cerium (Ce), lantanum (La), itrium (Y), dan zirkon (Zr) pada laterit bauksit. Data yang diperoleh dari penelitian ini akan digunakan sebagai bahan evaluasi untuk pengembangan eksplorasi torium pada cebakan laterit bauksit di Indonesia. Metode yang digunakan adalah pemetaan geologi, pengukuran kadar torium, dan pengambilan sampel konsentrat dulang untuk analisis mineral butir dan analisis kadar Ce, La, Y, dan Zr. Litologi yang menyusun daerah penelitian terdiri atas granit lapuk yang telah terubah menjadi laterit bauksit dengan kadar torium berkisar antara 25,9 hingga 177,8 ppm eTh. Konsentrat hasil pendulangan adalah konsentrat zirkon-ilmenit dengan kandungan mineral radioaktif terdiri dari zirkon, monasit, dan anatas. Kadar lantanum pada konsentrat zirkon-ilmenit adalah 0–412 ppm, cerium 0–80 ppm, itrium 27–82 ppm, dan zirkon 9.420–100.000 ppm. Keterdapatan torium pada endapan laterit bauksit di Pulau Singkep berhubungan erat dengan keterdapatan mineral zirkon, monasit, dan anatas. Karakterisrik keterdapatan torium pada endapan laterit bauksit mempunyai kemiripan dengan karakteristik keterdapatan torium pada cebakan timah primer dan sekunder. The thorium exploration in the last five years in the granite tin belt region is targeted at thorium availability in primary and secondary tin deposits. Singkep island is the part of granite tin belt which potential for thorium occurences either primer or secondary deposits. The purpose of this study was to determine the characteristics of thorium availability in bauxite laterite deposits concerning thorium content and its relation to the availability of radioactive minerals and cerium (Ce), lanthanum (La), Yttrium (Y), and zircon (Zr) contents on the bauxite laterite deposit. The data obtained from this study will be used as an evaluation material for the development of thorium exploration in bauxite laterite deposits in Indonesia. The methods used are geological mapping, thorium concentration measurements, and sampling of pan concentrate for mineral grain analysis and analysis of Ce, La, Y, and Zr contens. The lithology of the study area was granite that had weathered and turned into bauxite laterite deposit with thorium content ranging from 25.9 to 177.8 ppm eTh. The concentrate of the repeating result is zircon-ilmenite concentrate with radioactive mineral content composed of zircon, monazite, and anatase. La concentration on zircon-ilmenite concentrate is 0–412 ppm, Ce is 0–80 ppm, Y is 27–82 ppm and zircon is 9,420–100,000 ppm. Avaibility of thorium at the bauxite laterite deposit on Singkep Island is closely related to the zircon, monazite, and anatase minerals. Characteristics of thorium availability in the bauxite laterite deposit are similar to the thorium characteristics of the primary and secondary tin deposits.

Pola Tahanan Jenis dan Konduktivitas Batuan Mengandung Mineral Radioaktif di Botteng dan Takandeang, Mamuju, Sulawesi Barat

AbstrakKegiatan penyelidikan umum mineral radioaktif di daerah Mamuju, Sulawesi Barat merupakan tindak lanjut dari hasil pengukuran radioaktivitas lingkungan yang menunjukkan adanya nilai radioaktivitas tinggi. Kandungan mineral radioaktif yang cukup tinggi ditemukan antara lain di Desa Botteng dan Desa Takandeang yang tersusun oleh batuan berkomposisi leusit-basal tetapi karakteristik bawah permukaan daerah ini belum diketahui. Untuk mengetahui karakteristik geologi bawah permukaan, terkait dengan mineralisasi Uranium dan Thorium di daerah Botteng dan Takandeang, pengukuran geofisika menggunakan metode tahanan jenis dan polarisasi terimbas (Induced Polarization/IP) dilakukan. Pengukuran tersebut dilakukan menggunakan konfigurasi Wenner dan dipole-dipole, dimulai dengan pembuatan enam jalur pengukuran, masing-masing tiga jalur: GF/BTGY-01, GF/BTGK-02, dan GF/BTGK-04 di Botteng, dan tiga jalur lainnya: GF/TKDK-01, GF/TKDK-07, dan GF/TKDY-06 di Takandeang. Pengukuran dilakukan dengan memotong arah kemenerusan anomali radiometri permukaan. Hasil pengukuran menunjukkan keterdapatan anomali berada pada sebaran batuan autobreksia yang terlihat jelas di lokasi GF/TKDY-6, GF/TKDK-07, dan GF/BTGK-04. Beberapa indikasi mineralisasi di permukaan teridentifikasi di penampang GF/BTGK-02 dan GF/TKDK-01, dicirikan dengan anomali-anomali chargeabilitas >25,14 ms di lintasan GF/BTGK-02 dan 81,4 ms di GF/TKDK-01. Anomali yang signifikan direkomendasikan sebagai lokasi pemboran. AbstractThe general investigation activities of radioactive minerals in Mamuju Area, West Sulawesi is a respon of the environmental radioactivity measurement result, which shows the existence of high radioactivity value. High radioactive mineral content found in Botteng and Takandeang Villages. From the outcrops, they composed of leucite-basalt rocks; meanwhile the subsurface characteristics of this area are unknown. To characterize the subsurface geology, related to uranium and thorium mineralization in Botteng and Takandeang area, geophysical measurement conducted using resistivity and Induced Polarization (IP) methods. The measurements carried out using Wenner and dipole-dipole configurations. The measurements started with the creation of six measurement paths where three lines: GF/BTGY-01, GF/BTGK-02, and GF/BTGK-04 are in Botteng and three other lines: GF/TKDK-01, GF/TKDK-07 and, GF/TKDY-06 are in Takandeang. Measurements conducted by crossing the surface radiometric anomaly distribution. The result showed anomaly occurences on autobreccia distribution in GF/TKDY-6, GF/TKDK-07, and GF/BTGK-04 locations. Several mineralization indication on surface identified in GF/BTGK-0, and GF/TKDK-01 sections, charaterized by chargeability anomalies more than 25.14 ms and 81.4 ms respectively. All significant anomalies are recomended as drilling location.

Tataan Tektonika Batuan Gunung Api di Komplek Adang Kabupaten Mamuju Provinsi Sulawesi Barat

Kompleks batuan gunung api Adang di daerah Kabupaten Mamuju, Sulawesi Barat secara lebih detail dapat dikelompokkan menjadi tujuh, yaitu kompleks Tapalang, Ampalas, Adang, Malunda, Karampuang, Sumare, dan Labuan Rano. Komplek Adang merupakan salah satu komplek gunungapi utama yang masih dapat diidentifikasi bentukan morfologinya dengan baik. Komplek ini tersusunatas batuan gunung api basa hingga intermediet yang memiliki nilai laju dosis radiasi cukup tinggi yang disebabkan oleh kandungan mineral radioaktif di dalamnya. Keterdapatan mineral radioaktif pada batuan basaltik-andesitik belum pernah dijumpai di Indonesia sehingga hal ini menjadi sangat menarik untuk dilakukan penelitian terutama tataan tektonika pembentukan batuan komplek gunung api tersebut. Tujuan penelitian ini adalah untuk menentukan tipologi magmatik yang terkait dengantataan tektonikanya dengan pendekatan geokimia batuan gunung api menggunakan analisis X-Ray Fluorescence (XRF). Batuan gunung api Adang merupakan hasil dari proses vulkanisme suatu komplekgunung api yang memiliki pusat erupsi dan beberapa kubah lava. Batuan tersebut tersusun atas batuan trachyte-phonolite, dengan afinitas magmatiknya ultrapotasik, Dari data tersebut dapat diinterpretasi bahwa tataan tektonika magmatologinya adalah active continental margin(ACM). Magma asal yang membentuknya dari aktivitas gunung apinya dipengaruhi oleh kerak benua mikro barat daya (South West/SW) Sulawesi. Adang volcanic complexlocated in Mamuju Region, West Sulawesi can be grouped more detail into seven complexes that are Tapalang, Ampalas, Adang, Malunda, Karampuang, Sumare, and Labuan Rano. Adang complex is one of the main volcanic complexes that still can be identified with good morphological formations. This complex is composed of alkaline volcanic rocks with basic to intermediates composition that have high value of radiation dose rate caused by their radioactive mineral content. Radioactive mineral occurrences on the basaltic-andesitic rocks has never been found in Indonesia, so it becomes very interesting to do research mainly tectonic settings of the volcanic rock complex formation. The purpose of this study is to determine magmatiic typology related with the tectonic setting based on volcanic rock geochemistry using X-Ray Fluorences (XRF) analysis. Adang volcanic rock is the result of a complex process of volcanism having a volcanic center and several lava domes. They are composed of phonolite to dacite rock, with ultrapotassic affinity, interpretation of data concluded that tectonic setting of magmatism formed in active continental margin (ACM). Magmatism source from vulcanic activities influenced by South WestSulawesi micro-continental crust.