Geology of Byobu Rock and Gobanme Rock, Prince Olav Coast, East Antarctica

We report here the geology of Byobu Rock and Gobanme Rock outcrops hitherto unmapped in the Prince Olav Coast, East Antarctica. Both these outcrops expose high-grade metamorphic and igneous rocks. The metamorphic rock units comprise mainly of gneisses migmatized to variable extent and amphibolites, whereas igneous rocks comprise of granites and pegmatites. Preliminary structural data obtained from the outcrops identified the regional, steep to moderately dipping foliation trend in the WNW-ESE at Byobu Rock, whereas they trend in the NW-SE direction at Gobanme Rock. Two generations of folding were identified, an earlier tight isoclinal intrafolial folds and a late regional open fold. The three deformational events identified are comparable and consistent with those reported in the neighboring outcrops in the Prince Olav Coast. Metamorphic P-T conditions estimated based on various geothermobarometries indicate that the rocks have experienced granulite grade conditions during peak metamorphism (770-880°C and 6-9kbar). The finding of orthopyroxene at Byobu Rock in this study extends the orthopyroxene-in isograd in the progressive metamorphic zone in the Lutzow-Holm Complex further eastward beyond Tenmondai Rock. Inclusions of kyanite within garnet in metapelitic rocks suggest a clockwise P-T path, consistent with the P-T paths suggested for the Lutzow-Holm Complex. Preliminary bulk rock geochemical investigations indicate that granitic rocks and quartzo-feldspathic gneiss mostly belong to volcanic arc granite suite, though their origin remains indistinct. Electron microprobe dating of monazites from representative rocks gave Pan-African ages (557±33Ma), consistent with the regional metamorphic ages reported earlier. Thus, based on the similarities on structural, petrological, geochemical and geochronological data, the Byobu Rock and Gobanme Rock are considered to be integral part of the Pan-African Lutzow-Holm Complex with analogous geological history

Calc-silicate rocks and marbles from Lutzow-Holm Complex,East Antarctica, with special reference to the mineralogy and geochemical characteristics of calc-silicate mega-boudins from Rundvagshetta

We report here the mode of occurrence of calc-silicate rocks and marbles from the Lutzow-Holm Complex, East Antarctica, and a worked example from Rundvagshetta. Calc-silicate boudins were observed in Cape Hinode, Akarui Point, Byobu Rock, Skarvsnes, Skallevikshalsen and Rundvagshetta, whereas they were reported earlier from Sinnan Rock, Cape Ryugu, Akebono Rock, Cape Hinode, Niban Rock, Kasumi Rock, Daruma Rock, Cape Omega, Langhovde, Ytrehovdeholmen and Skarvsnes. They vary in size from decimeters to few meters and are commonly enclosed within pelitic or psammitic gneisses. In addition, extensive layers of marbles and calc-silicate rocks are distributed in Skallevikshalsen. The calc-silicate mega-boudins within the layered pyroxene-gneiss from Rundvagshetta, up to 5m long and 2m thick, comprises of coarse to medium grained assemblage of scapolite+anorthite+garnet+clinopyroxene+calcite+quartz+titanite±wollastonite. Co-existing scapolite and plagioclase suggest a "minimum" estimate of peak metamorphic temperature of ～830°C . Peak metamorphic mineral assemblages equilibrated at moderate to high X_(CO2) conditions (0.3-0.7) and temperatures between 850 and 1000°C , consistent with the ultrahigh temperature metamorphic conditions reported in the region. Multistage garnet corona formation preserved in the calc-silicate assemblage suggests a local increase in hydrous fluid activity during retrogression. Preliminary bulk rock geochemistry of different mineralogical zones in the boudin shows chemical potential gradients in some major elements, especially SiO_2, Al_2O_3 and CaO, possibly controlled by the compositional variations in the protolith. Altogether, these results suggest that calc-silicate rocks preserve information on the metamorphic evolution and help us in deducing the geodynamic evolution of high-grade terrains

Geochemistry of mafic metamorphic rocks in the Lutzow-Holm Complex, East Antarctica: Implications for tectonic evolution

Mafic metamorphic rocks are widely distributed through the Lutzow-Holm Complex (LHC) of East Antarctica, as layers between or enclaves within metasedimentary and metaigneous lithologies. It has been inferred that the peak metamorphic grade of the LHC progressively increases in a southwestern direction from amphibolite-facies to granulite-facies conditions, with mineral assemblages in the mafic metamorphic rocks changing from hornblende (magnesiohornblende)±biotite+plagioclase to orthopyroxene+clinopyroxene±hornblende (pargasite, magnesiohasting-site and tschermakite)±biotite±garnet+plagioclase. Field relationships suggest that amphibolite-grade mafic metamorphic rocks derive from mafic magma intruded into metasedimentary units, whereas granulite-facies mafic metamorphic rocks are a mixture of detrital blocks and mafic sill or intrusions. Major and trace element compositions of mafic metamorphic rocks are similar to those of igneous rocks of tholeiite affinity, and can be divided into volcanic-arc basalt (VAB)-type or mid-ocean ridge basalt (MORB)-type compositions. On a regional scale, VAB-type lithologies are predominant in amphibolite-facies areas, and MORB-type lithologies predominate in granulite-facies areas. On the basis of HFSE concentrations and Nb/Y ratios, MORB-type lithologies have T-type and E-type MORB compositions with oceanic plateau basalt and back-arc basin basalt affinities, and are occasionally found in the field intercalated with metasedimentary layers, characteristic of magmatism and sedimentation cycles in a marginal sea basin setting. Such field relationships provide information on the tectonic environment of protolith formation in the LHC. Various crustal components have been amalgamated into a relatively narrow mobile belt, which was subjected to high-grade metamorphism during the final closure of oceanic basins as a result of continent-continent collision

Granulites from Cape Hinode in the amphibolite-facies eastern part of Prince Olav Coast, East Antarctica: New evidence for allochthonous block in the Lutzow-Holm Complex

High-grade metamorphic rocks occurring along the Prince Harald, Soya, and Prince Olav Coasts make up the Latest Proterozoic-Early Paleozoic Lutzow-Holm Complex, which is the youngest orogenic belt in the East Antarctic Shield. A systematic increase in metamorphic grade from east to west, ranging from upper amphibolite facies on the eastern Prince Olav Coast to upper granulite facies at the head of Lutzow-Holm Bay, has been well-established in the complex. However, granulites are newly found to occur as blocks sitting within meta-tonalites at Cape Hinode located on the amphibolite-facies eastern Prince Olav Coast. In addition, it is newly revealed that kyanite occurs rather commonly in meta-tonalites which contain hornblende with or without clinopyroxene. The modes of occurrence in the field, petrographical features, and major element bulk rock compositions of the granulites and related rocks are given in some detail in this study. These, along with the previously presented geochronological, geochemical and petrographical data, would indicate that the rocks in the Cape Hinode area as a whole make up a Mesoproterozoic allochthonous block in the Latest Proterozoic-Early Paleozoic Lutzow-Holm Complex

Mobile monitoring along a street canyon and stationary forest air monitoring of formaldehyde by means of a micro gas analysis system

A micro-gas analysis system (μGAS) was developed for mobile monitoring and continuous measurements of atmospheric HCHO. HCHO gas was trapped into an absorbing/reaction solution continuously using a microchannel scrubber in which the microchannels were patterned in a honeycomb structure to form a wide absorbing area with a thin absorbing solution layer. Fluorescence was monitored after reaction of the collected HCHO with 2,4-pentanedione (PD) in the presence of acetic acid/ammonium acetate. The system was portable, battery-driven, highly sensitive (limit of detection = 0.01 ppbv) and had good time resolution (response time 50 s). The results revealed that the PD chemistry was subject to interference from O3. The mechanism of this interference was investigated and the problem was addressed by incorporating a wet denuder. Mobile monitoring was performed along traffic roads, and elevated HCHO levels in a street canyon were evident upon mapping of the obtained data. The system was also applied to stationary monitoring in a forest in which HCHO formed naturally via reaction of biogenic compounds with oxidants. Concentrations of a few ppbv-HCHO and several-tens of ppbv of O3 were then simultaneously monitored with the μGAS in forest air monitoring campaigns. The obtained 1 h average data were compared with those obtained by 1 h impinger collection and offsite GC-MS analysis after derivatization with o-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine (PFBOA). From the obtained data in the forest, daily variations of chemical HCHO production and loss are discussed

ダイ46ジ ナンキョク チイキ カンソクタイ リュツォ・ホルムワン , プリンスオラフ カイガン オヨビ ニシ エンダビーランド チシツ・コチジキ カキ ヤガイ チョウサ ホウコク 2004-2005

第46次南極地域観測隊は,リュツォ・ホルム湾,プリンスオラフ海岸及び西エンダビーランドの露岩域を対象に,2004年12月17日から2005年2月17日にかけて地質・古地磁気野外調査活動を行った.この観測は,南極地域観測第VI期計画のプロジェクト研究観測「南極域から探る地球史」の中の「東南極リソスフェアの構造と進化の研究II」の一環として計画立案されたものである.第46次夏期観測では野外観測支援のための小型ヘリコプターが導入され,「しらせ」搭載ヘリコプターとともに野外調査の支援作業にあたった.ここでは,観測計画を実施するための,主に設営面での計画,準備,そして活動経過と問題点について報告する.The 46th Japanese Antarctic Research Expedition (JARE-46) conducted field operations on geological and paleomagnatic studies in the regions of Lutzow-Holm Bay, Prince Olav Coast and western Enderby Land during December 17, 2004 through February 17, 2005, under a part of the SEAL II (Structure and Evolution of East Antarctic Lithosphere II) project. A small helicopter was used to support field parties during the summer operations conducted by JARE-46. This report summarizes preparations for field operations and activities of the geological and paleo-magnetic team, and points out some problems for the future planning

Report on the activities of geological and paleomagnetic surveys in the regions of Lutzow-Holm Bay, Prince Olav Coast and western Enderby Land during JARE-46

The 46th Japanese Antarctic Research Expedition (JARE-46) conducted field operations on geological and paleomagnatic studies in the regions of Lutzow-Holm Bay, Prince Olav Coast and western Enderby Land during December 17, 2004 through February 17, 2005, under a part of the SEAL II (Structure and Evolution of East Antarctic Lithosphere II) project. A small helicopter was used to support field parties during the summer operations conducted by JARE-46. This report summarizes preparations for field operations and activities of the geological and paleo-magnetic team, and points out some problems for the future planning

Development of a Novel Antifouling Platform for Biosensing Probe Immobilization from Methacryloyloxyethyl Phosphorylcholine-Containing Copolymer Brushes

The immobilization of thiol-terminated poly­[(methacrylic acid)-<i>ran</i>-(2-methacryloyloxyethyl phosphorylcholine)] (PMAMPC-SH) brushes on gold-coated surface plasmon resonance (SPR) chips was performed using the “grafting to” approach via self-assembly formation. The copolymer brushes provide both functionalizability and antifouling characteristics, desirable features mandatorily required for the development of an effective platform for probe immobilization in biosensing applications. The carboxyl groups from the methacrylic acid (MA) units were employed for attaching active biomolecules that can act as sensing probes for biospecific detection of target molecules, whereas the 2-methacryloyloxyethyl phosphorylcholine (MPC) units were introduced to suppress unwanted nonspecific adsorption. The detection efficiency of the biotin-immobilized PMAMPC brushes with the target molecule, avidin (AVD), was evaluated in blood plasma in comparison with the conventional 2D monolayer of 11-mercaptoundecanoic acid (MUA) and homopolymer brushes of poly­(methacrylic acid) (PMA) also immobilized with biotin using the SPR technique. Copolymer brushes with 79 mol % MPC composition and a molecular weight of 49.3 kDa yielded the platform for probe immobilization with the best performance considering its high S/N ratio as compared with platforms based on MUA and PMA brushes. In addition, the detection limit for detecting AVD in blood plasma solution was found to be 1.5 nM (equivalent to 100 ng/mL). The results have demonstrated the potential for using these newly developed surface-attached PMAMPC brushes for probe immobilization and subsequent detection of designated target molecules in complex matrices such as blood plasma and clinical samples