Geology and Petrograpby of the Yamato Sanmyaku, East Antarctica

The Yamato Sanmyaku is a mountain range located at about 200km south of the Prins Harald Kyst, East Antarctica. The range forms an arcuate chain, extending 50km north-south, comprising seven massifs temporarily named A, B, C, D, E, F and G. The rocks of the area are divided into a charnockitic group (pyroxene gneisses and pyroxene syenites) and a granitic group (migmatitic gneisses, granitic gneiss, and microcline granites). In addition, metabasite interlayers and metadikes are found everywhere, associated with microcline pegmatites. The charnockitic group is involved in the older complex which crystallized under the conditions of a granulite facies. It has been partly modified by later granitization related to the granitic group which itself shows various stages of granitization. The grade of metamorphism increases towards the north, parallel to the gneissosity. The intercalated metabasite layers correspond to the host rocks in mineral paragenesis. Basic dikes are intruded obliquely into both the granitic gneisses and the pyroxene syenites, and are metamorphosed into various metabasites under the conditions of an amphibolite facies. This metamorphism is probably related to the subsequent intrusion of microcline granites and associated microcline pegmatite. A thrust movement from east to west represents the last stage of the structural evolution

Tectonics and Petrograpby of the East Ongul Islana, Lutzow-Holm Bukt, Antarctica

The East Ongul Island on the coast of the Lutzow-Holm Bukt, East Antarctica, was investigated from the tectonical and petrographical points of view. The rocks exposed in the island are petrographically classified into the following seven types : 1) Metabasites, 2) Pyroxene gneisses, 3) Hornblende gneisses, 4) Garnet gneisses, 5) Granites, 6) Feldspathic rocks, and 7) Pegmatites. It is verified that the unique structural feature of the island is represented by the isoclinal fold recumbent to the west with the frontal zone in which many small anticlinal as well as synclinal folds occur. The inner core of the main anticline is generally composed of the garnet gneisses with the pyroxene gneisses forming the outer mantle. The hornblende gneisses, which are distributed in front of the recumbent anticline, occur in the same horizon as the pyroxene gneiss, so the former may have been converted from the latter. This is also confirmed by the geological and petrographical observations. Besides, the hornblende gneiss zone coincides with the zone of granite and subsequent microcline pegmatite emplacement. The lineation of the rocks, represented by the undulating foliation, is defined to be a b-lineation parallel to the fold axis, but another lineation with the same character but perpendicular to the fold axis is also found. The fracture systems indicated by the pegmatite and joint patterns were analyzed by tectonic dating. The pegmatite intruded at the earlier folding stage, whereas the joint pattern was formed at the later upwarping stage. The gneisses and granites are classified mainly by the characteristic mafic minerals, and their modes of occurrence as well as the optical mineralogy are described. The optical data of the constituent minerals revealed that there is a tendency that the Fe/Mg ratio of the mafic minerals such as pyroxene, hornblende, biotite and garnet, may increase with acidity of the rocks, from the matabasites to the granites. The anorthite content of plagioclase is restricted within a rather narrow range between 22% and 35% when feldspar coexists with potash-feldspar, although that of plagioclase in metabasite and basic enderbitic pyroxene gneiss free from potash-feldspar ranges widely from 42% to 93%. The triclinicity of the potash-feldspar may become higher in the granite than the gneisses judging from the data of their 2V values. It is probable that the gneisses were formed originally under the condition of a granulite facies in the regional metamorphism. At the same time, the widespread developement of hornblende and biotite in the metabasites and gneisses suggests subsequent changes in temperature and pressure or the presence of water as well as changes in chemical composition which facilitated the mobilization and plastic deformation of the rocks. It is considered that two phases of metamorphism may be detected in the area; the granulite facies at an earlier phase and the amphibolite facies at a later phase. This has been suggested by the investigations not only in other regions of the East Antarctica but also in other Precambrian shields of the world

3 ヤマト サンミャク チシツ チョウサ ホウコク ヨホウ ダイ4ジ エットウタイ ヤマト サンミャク チョウサ リョコウ ホウコク ヨホウ

やまと山脈は,A～G(仮称)の7つの山塊よりなり,一種の弧状構造を示している.これらの山塊は,片麻岩類,深成岩類,変基性岩及びペグマタイトによって構成されるが,今回の調査旅行で採集された資料の整理分析によって,将来より詳しい結果が明らかにされるであろう

シラセタイ ニヨッテ サイシュウ サレタ キングエドワード ナナセイ リクチ ノ ガンセキ ニ カンスル オボエガキ

1911年～1912年にわたって,白瀬隊はロス氷床に上陸南下を試みたが,その間,開南丸は東方キングエドワード七世陸地に向って調査を行い,岩石と皇帝ペンギンを採集してきた.これらの岩石についての記載はこれまで行われていず,またキングエドワード七世陸地がアンデス褶曲帯に属するものか,あるいは,東部南極大陸の先カンブリア紀楯状地に属するものか,はっきりされていない状態である.幸い,当時の岩石標本の薄片が東京大学地質学教室に保存されてあり,とくに久野教授のおすすめと御好意により,その薄片を拝借して検鏡することができた.それによる記載と多少の考察をのべた.スチゥワート(1939)やフェアブリッヂ(1952)はキングエドワード七世陸地の岩石は東部南極大陸の先カンブリア紀楯沃地に属するものと述べているが,岩石学的にみて仏スチゥワートの分類の規準に反するものが多く,必ずしも先カンブリア紀のものというきめてはない.むしろどちらかと云えば,アンデス摺曲帯に属するものと云えそうである.何しろ薄片が六枚で,標本自体が見当らないのであるから,はっきりした結論は出す方が無理である.皇帝ペンギンの胃の中から発見された岩石片は,東方のエドセルフォー下山脈のものとまったく同じで,この山脈はアンデス摺曲帯に属するものである.これは,ペンギンがエドセフォード山脈の附近から氷に乗って流れてくる可能性が考えられるが,そうでないとしたら面白いことになる.今後の調査が期待されるゆえんであ

ナンキョク ハムナ ヒョウバク オヨビ ホノールブルッガ ヒョウガ ニオケル コウゾウ ヒョウガガク ノ ケンキュウ

リュッツォホルム湾沿岸には,大陸氷床に源を特つ多くの氷河や氷爆が存在する.そのなかの,ハムナ氷爆とホノールブルッガ氷河を研究の対象とした.この報告は,構造氷河学,つまり,微視的な氷結晶の方位をしらべるだけでなく,巨視的な氷河構造をも含めた予察的な研究である.しかし,ホノールブルッガ氷河の巨視的構造については,その巨大さと表面構造の複雑さ,危険さのために調査はできなかった.氷河の構造は,多くの面構造によって特徴付けられている.それらを次のように分けた.廊下(corridor),クレバス(crevass).透明縞(clear band),片理(foliation),断層(fault),節理(joint),劈開(cleavage).この分類はあくまで現象的なものであり,すべて氷河流動に伴う一連の変形の産物である.氷結晶の方位は,全てこれらの面,とくに透明縞,片理,劈開などの運動面に規定されて発達している.そのパターンは,底面を滑り面とする極大値をひとつ持つもの(single maximum)をはじめとして,偏圧あるいは剪断応力の増加にしたがって,4-極大値を持つダイアモンド型パターン,さらに,5-極大値を持つものに発達する.これらの現象は,RIGSBY(1958)やKAMB(1959)の多極大値にかんする仮説では説明できない.筆者は偏圧の強さに対応して氷結晶の滑り面が変化するために単極大値から多極大値に発展すると考えた.また,氷結晶の波動消光によって認められる結晶軸のわずかな移動とそれに伴う紬粒化作用(polygonization)を観察した.これは,氷結晶の定方位をもたらす初期段階の機構を示すものであろう

ナンキョク ヒガシ オングルトウ ノ コウゾウ チシツ オヨビ ガンセキ ダイ1ブ コウゾウ チシツ

東オングル島は,南北2.5km,東西2kmの小島で,まわりはいくつかの小さな島をめぐらしている.地形図は,地理調査所(現国土地理院)作製による1:5,000地形図を使用することができた.この島は,各種の片麻岩から構成されている.チャーノカイト質片麻岩(立見,菊池により閃緑岩質片麻岩とされたもの)・角閃石片麻岩・柘榴石片麻岩(同上花崗閃緑岩質片麻岩)・花崗岩シートおよび花崗岩質,含角閃石二種のペグマタイトである.この地域の構造の特徴は,ひとつの大きな西側に倒れた等斜褶曲構造である.その前面には,小褶曲の重なりあった前縁帯が,主褶曲に沿って南北に分布する.これら褶曲の内核に柘榴石片麻岩が分布している.褶曲の外郭は,チャーノカイト質片麻岩でとりかこまれているが,小褶曲帯の西側(前面)は,角閃石片麻岩帯となっている.この帯は,花崗岩シートの迸入帯であり,その交代作用によって,チャーノカイト質片麻岩が角閃石片麻岩に変ったものである(Fig. 5).線構造は,片理のうねりである.その方向と落しは,褶曲軸のそれと一致する(b-線構造).ところが,島の西部では,同じ性格の線構造が,褶曲軸に直角なa-線構造となっている(Fig. 1, Plate1).このことは,線構造形成が,主運動と直接関係のない,第2次の部分運動によることを示している,ペグマタイトと節理とは,運動後半の断裂ではあるが,そのパターンは一致しない.これは,その形成時期にずれがあるからである.ペグマタイトは褶曲の主運動期,節理はそれにやや遅れた曲隆運動期のものであろう.褶曲から断裂形成・衝上にいたる運動と,片麻岩の交代作用や花崗岩・ペグマタイトの迸入とには,深い関係が認められる

Petrographic Studies of Potash Feldspar from the Yamato Sanmyaku, East Antarctica

The Yamato Sanmyaku is a mountain range located about 200km south of Prins Harald Kyst, East Antarctica. The mountains are composed of charnockitic group and granitic group rocks which were described geologically and petrographically by K. KIZAKI (1965). The present paper deals with the potash feldspars from the charnockitic group and pegmatites. The occurrence of the potash feldspars and their optical characteristics are described first, revealing the mechanism of albitization of potash feldspars which have a wide range in the optical axial angle. Next, the two-feldspar geothermometry method is applied to the potash feldspars from the Yamato Sanmyaku and the results are compared with that of the Norwegian potash feldspars and also with the data of Japanese plutonic rocks. The formation temperatures estimated from the distribution coefficient k, triclinicity and 2Vx value are discussed on the basis of the subsolidus phase relation, the relation between the formation temperature and crystal symmetry, and the relation between the optical axial angle and triclinicity. These relations well support the conclusion held from the geological and petrographical points of view that the charnockitic rocks were originally formed under a granulite facies condition, but their characters were influenced more or less by the subsequent granitization under an amphibolite facies condition

Cloning and expression of SOLD1 in ovine and caprine placenta, and their expected roles during the development of placentomes

<p>Abstract</p> <p>Background</p> <p>The Ly-6 (Ly-6/uPAR) superfamily members share the Ly-6 domain defined by distinct disulfide bonding patterns between 8 or 10 cysteine residues. They comprise membrane- and secretory-type proteins. We recently reported the gene and protein characterization of the bovine secreted protein of Ly-6 domain 1 (SOLD1). Bovine SOLD1 is expressed in trophoblast mononucleate cells (TMCs) and is localized in the cotyledonary mesenchyme. Here, we compared the expression and functionality of SOLD1 among the ruminants. We examined mRNA expression by chorionic fibroblasts as a measure of one of the SOLD1 functions.</p> <p>Results</p> <p>Ovine and caprine SOLD1 mRNAs have 303 bp open reading frames and encode for deduced SOLD1 proteins with 100 amino acids, including a 22-aa-long signal peptide at the N-terminal. Both of the SOLD1 amino acid sequences have high similarities with the bovine sequence. Both SOLD1 mRNAs were also expressed in TMCs of cotyledons and intercotyledonary membranes. The mature SOLD1 proteins were localized in the mesenchymal villi of cotyledons after secretion. Bovine, ovine and caprine SOLD1 affected gene expression in mesenchymal fibroblasts <it>in vitro</it>; nucleoredoxin expression was upregulated and BCL2-like 13 was downregulated. Thus, we suggest that SOLD1 acts as a modulator of cell proliferation and apoptosis.</p> <p>Conclusion</p> <p>Expressing cells and protein localization of SOLD1 coincided among the three ruminants. SOLD1 participated in regulating nucleoredoxin and BCL2-like 13 expression in chorionic fibroblasts. SOLD1 is produced specifically in the cotyledons and intercotyledonary membranes in ruminants and appears to be involved in the construction of the ruminant placenta.</p