Asuka 12325: A new depleted shergottite

The Tenth Symposium on Polar Science/Special session: [OA] Antarctic meteorites, Thur. 5 Dec. / 3F Multipurpose conference room, National Institute of Polar Researc

Reconstructing seasonality through stable-isotope and trace-element analyses of the Proserpine stalagmite, Han-sur-Lesse cave, Belgium : indications for climate-driven changes during the last 400 years

Fast-growing speleothems allow for the reconstruction of palaeoclimate down to a seasonal scale. Additionally, annual lamination in some of these speleothems yields highly accurate age models for these palaeoclimate records, making these speleothems valuable archives for terrestrial climate. In this study, an annually laminated stalagmite from the Han-sur-Lesse cave (Belgium) is used to study the expression of the seasonal cycle in northwestern Europe during the Little Ice Age. More specifically, two historical 12-year-long growth periods (ca. 1593-1605 CE and 1635-1646 CE) and one modern growth period (1960-2010 CE) are analysed on a sub-annual scale for their stable-isotope ratios (delta C-13 and delta O-18) and trace-element (Mg, Sr, Ba, Zn, Y, Pb, U) contents. Seasonal variability in these proxies is confirmed with frequency analysis. Zn, Y and Pb show distinct annual peaks in all three investigated periods related to annual flushing of the soil during winter. A strong seasonal in-phase relationship between Mg, Sr and Ba in the modern growth period reflects a substantial influence of enhanced prior calcite precipitation (PCP). In particular, PCP occurs during summers when recharge of the epikarst is low. This is also evidenced by earlier observations of increased delta C-13 values during summer. In the 17th century intervals, there is a distinct antiphase relationship between Mg, Sr and Ba, suggesting that processes other than PCP, i.e. varying degrees of incongruent dissolution of dolomite, eventually related to changes in soil activity and/or land-use change are more dominant. The processes controlling seasonal variations in Mg, Sr and Ba in the speleothem appear to change between the 17th century and 1960-2010 CE. The Zn, Y, Pb, and U concentration profiles; stable-isotope ratios; and morphology of the speleothem laminae all point towards increased seasonal amplitude in cave hydrology. Higher seasonal peaks in soil-derived elements (e.g. Zn and Y) and lower concentrations of host-rock-derived elements (e.g. Mg, Sr, Ba) point towards lower residence times in the epikarst and higher flushing rates during the 17th century. These observations reflect an increase in water excess above the cave and recharge of the epikarst, due to a combination of lower summer temperatures and increased winter precipitation during the 17th century. This study indicates that the transfer function controlling Mg, Sr and Ba seasonal variability varies over time. Which process is dominant - either PCP, soil activity or dolomite dissolution - is clearly climate driven and can itself be used as a palaeoenvironment proxy

Report of the JARE-54 and BELARE 2012-2013 joint expedition to collect meteorites on the Nansen Ice Field, Antarctica

第54次日本南極地域観測隊員4名とベルギー南極観測隊員6 名の合計10名から構成される隕石探査隊は，2012年12月から2013年2月まで，セール・ロンダーネ山地南部に広がるナンセン氷原（南緯72°30′-73°，東経23°-25°，標高約2900-3000m）において隕石探査を実施した．ナンセン氷原には2012年12月26日から2013年2月2日まで39日間滞在した．今回の探査域は第29次日本南極地域観測隊以降探査が行われていない．探査の結果，採集した隕石の総数は424個，合計重量は約70kgであった．隕石発見地点は携帯GPSに記録されたので，探査域における隕石の分布が明確になった．これは隕石集積機構解明のための基礎データだけでなく，今後の探査計画に活用できる．本稿は主に日本隊による準備期間を含む実施報告書である．This paper reports on a joint expedition (JARE-54 and BELARE 2012-2013) that conducted a search for meteorites on the Nansen Ice Field, Antarctica, in an area south of the Sor Rondane Mountains (72°30′-73°S, 23°-25°E; elevation 2900-3000 m). The expedition took place over a period of 39 days during the austral summer, between 26 December 2012 and 2 February 2013. The team consisted of ten members: three researchers and one field assistant from the 54th Japanese Antarctic Research Expedition (JARE-54), and five researchers and one field assistant from the Belgian Antarctic Expedition (BELARE) 2012-2013. Previously, this area had only been searched by JARE-29. The team collected 424 meteorites, which had a total weight of about 70 kg. The search tracks of the ten members of the expedition were recorded using hand-held GPS units, and this allowed the distribution of meteorites within the searched area to be mapped. The resultant data will be useful for planning future expeditions and can be used to clarify the meteorite concentration mechanism on the ice field. This paper focuses on the activities of JARE-54 during the joint expedition

Exploring sedimentary micrometeorite traps in Western Greenland

The 14th Symposium on Polar Science/Ordinary sessions [OA] Antarctic Meteorite, Tue. 14 Nov. / 3F Multipurpose Conference room, Institute of Statistical Mathematicsconference objec

The effect of fluid alteration in Antarctic chondrites

The 14th Symposium on Polar Science/Ordinary sessions [OA] Antarctic Meteorite, Tue. 14 Nov. / 3F Multipurpose Conference room, Institute of Statistical Mathematicsconference objec

Quantitative elemental mapping of chondrites using LA-ICP-TOF-MS

The 15th Symposium on Polar Science/Ordinary sessions [OA] Antarctic Meteorite, Thu. 5 Dec. / 3F Conference room, The Institute of Statistical Mathematicsconference outpu

Stable isotope ratios and trace elements in modern mammal tooth enamel

Bioapatite from mammal tooth enamel is a popular biomineral used in the reconstruction of palaeoenvironment and palaeodiet. It records information about the animal’s environment and diet on a sub-annual scale and is proven to be highly resistant to diagenesis, allowing the preservation of its original chemical composition through archaeological and geological timescales. In this study, stable carbon and oxygen isotope analysis are used as a stepping stone to investigate the use of other chemical proxies for the reconstruction of environment and diet from mammal teeth. Concentration profiles of trace element distributions (measured with μXRF and cross-validated with Laser Ablation ICP-MS) and stable isotope ratios (13Cap, 18Oc & 18Op) are combined to test the reliability of trace element profiles from mammal teeth in recording seasonal changes in environment and diet of the animal. A method is presented that links the various geochemical records within a tooth sequence using mineralization sequences and oxygen isotope seasonality. This way, a 3 year trace element and stable isotope record from horse tooth enamel is created showing seasonal variation in trace elements and isotope ratios linked to changes in climatic conditions and diet through the animal’s lifetime. This study shows how an entire new set of trace element proxies, that can be measured quickly and non-destructively, may yield information on palaeoenvironment and palaeodiet. These trace element measurements yield information from precious archaeological samples that could otherwise be obtained solely through destructive sampling. The versatility of the μXRF and LA- ICP-MS methods opens up a wide range of applications for trace element analysis in archaeology

Antarctic micrometeorites as a resource to complement the current Solar System inventory: the case of 16O-poor cumulate porphyritic cosmic spherules

The 14th Symposium on Polar Science/Ordinary sessions [OA] Antarctic Meteorite, Tue. 14 Nov. / 3F Multipurpose Conference room, Institute of Statistical Mathematicsconference objec