原特提斯的消減極性:西昆侖128公里巖體的啟示

The Yirba (128 km) pluton is an early Paleozoic dioritic intrusion of western Kunlun orogenic belt, northwest China as an important element when reconstructing the evolution history of this belt. Due to the scarcity of field data and methodological difference in studying this pluton, however, no consensus for its age, source and tectonic setting has been adopted. In this paper, we present new geochronological and geochemical data for the Yirba pluton, aiming to better understand its age, source, and hence the early Paleozoic tectonic evolutionary history of western Kunlun. U-Pb data by single grain zircon analyses suggest that the Yirba pluton was emplaced 471 ± 5 Ma ago and contains ca. 490 Ma zircon grains inherited from source, or captured in the magma chamber. The pluton is enriched in Al 2 O 3 (15.7% ∼ 18.4%), Sr (470 ∼ 864 μg/g) and other LILEs (large ion lithosphile elements), but relatively depleted in HFSE (high field strength elements and HREE), with LREE-enriched patterns and low to medium europium anomalies (δEu = ∼ 0.7), showing typical characteristics of I-type, volcanic arc granitoids. Although its relatively high Al 2 O 3, Sr and low MgO contents make it resemble adakite, its relatively high Yb (1.92 ∼ 2.88 μg/g), Y (19.4 ∼ 34.0 μg/g) contents, low Sr/Y (24.2 ∼ 37.0) , Zr/Sm (7.3 ∼ 21) and relatively high initial Sr isotope ratios (0.7075 ∼ 0.7091) do not support a subducting slab origin. Its Nd model ages (1.06 ∼ 1.35 Ga) indicate a juvenile source, while its O isotope compositions (+5.7‰ ∼ + 7.4‰) and Sr-O isotope relationship preclude significant involvement of sialic materials. The major, trace, REE and Nd-Sr-O isotope compositions strongly suggest that the Yirba pluton was formed by partial melting of mafic lower crust in a southward growing, active continental margin environment. The existence of volcanic arc granitoids in the south margin of the North Kunlun terrane suggests that the subduction polarity of the Proto-Tethys was northward.128公里巖體是西昆侖造山帶中一個早古生代的花崗閃長巖體,長期以來一直是研究西昆侖構造演化的重要參考依據。然而由于區域地質資料的不足和研究手段的不同,對該巖體的形成年代、源區性質以及構造背景等方面還存在著不同的認識。本文試圖通過地質年代學和地球化學方面的研究,明確128公里巖體的成巖時代和構造背景,進而制約西昆侖的早古生代構造演化。單顆粒鋯石的U-Pb定年結果表明128公里巖體形成于471±5 Ma并含有可能形成于早期巖漿房或繼承自源區的490 Ma左右的鋯石。128公里巖體富Al_2O_3(15.7％～18.4％),Sr(470～864μg/g)和大離子親石元素但相對虧損 高場強元素,相對富集輕稀土且具有低到中等的負銪異常(δEu=～0.7),顯示出典型的Ⅰ型弧花崗巖特征。盡管其富集Al_2O_3、Sr、相對低的MgO含量和Y/Yb比值使其非常類似于埃達克巖,但其相對高的Yb(1.92～2.88μg/g)、Y(19.4～34.0μg/g)含量,低的Sr/Y(24.2～37.0)和Zr/Sm(7.3～21)比值以及相對高的初始Sr同位素組成(0.7075～0.7091)排除了消減板塊在石榴石穩定區發生部分熔融的可能性。低的氧同位素组成( + 5.7％～7.4％) 以及Sr-O 同位素关系表明该岩体并非形成于地慢来源的岩泉与变质围岩间的同化混染。高的稀土含量、明显的稀土分馏以及相对高的Sr 同位素组成表明12 8 公里岩体不大可能形成于受陆源物质影响较小的大洋岛弧, 而更可能形成于活动大陆边缘环境中基性地壳物质的部分熔融。北昆仑地体的南缘存在火山弧型花岗岩的事实表明, 原特提斯的消减方向应当是向北的。published_or_final_versio

阿爾泰哈巴河群的沉積時代及其構造背景

Habahe Group mainly consists of elastic sediments, which widely distribute in the Chinese Altai and can provide important constraints on the tectonic evolution of the Central Asian Orogenic Belt (CAOB). However, there are different opinions about its deposition time and tectonic background. Previous studies suggested that the Habahe Group formed in Sinian to Mid-Ordovician or Mid- to Late Ordovician in a passive continental margin. On the other hand, recent geological investigations reveal a long lasting subduction-related setting in the Chinese Altai at least since Cambrian. The current geochronological study for detrital zircons from the Habahe Group reveals that the detrital zircons of individual samples, irrespective of their lithological and metamorphic differences, all show similar age patterns, with the early Paleozoic ( 206Pb/ 238U age = 463 ± 542Ma) grains predominating. The youngest detrital zircons from different samples display similar ages (ca. 470Ma), which may reflect the maximum deposition time of the Habahe Group. Dating of growth rim of detrital zircons from migmatite yielded a Mid-Devonian age (384 ± 6Ma), which was coeval with intrusion of Early to Mid-Devonian granitic plutons in the area and clearly indicates the minimum deposition time of the Hababe Group. Therefore, the deposition time of the Habahe Group can be constrained to be Mid-Ordovician to Early Devonian. Zircon U Pb dating results indicate that the detrital zircons of the Habahe Group are dominated by early Paleozoic grains, with small proportion formed in Precambrian. The early Paleozoic detrital zircons are mostly magmatic in origin, and their less rounded shapes indicate a limited transportation. The age and morphological characteristics of the detrital zircons are consistent with those of detrital zircons in active tectonic settings and indicate that the Chinese Altai was under an active continental margin environment during the Early Paleozoic. 北疆阿爾泰造山帶的哈巴河群變質碎屑巖分布廣泛,其沉積時代和構造環境對于認識中亞造山帶的演化歷史有重要意義。早期研究認為哈巴河群沉積于震旦紀—中奧陶世時期,形成于被動大陸邊緣構造環境。而最近有學者根據中亞造山帶的地質演化背景提出,阿爾泰形成于活動陸緣構造環境。對哈巴河群中碎屑鋯石的年代學研究表明,不同巖性或變質程度不同的樣品碎屑鋯石主要類群具有相似的年齡分布特征,其206Pb/238U 年齡主要介于463～542Ma 之間。在這些樣品中, 最年輕的碎屑鋯石年齡均集中于470Ma 左右,代表了碎屑沉積的時代下限。而哈巴河群混合巖樣品中碎屑鋯石增生邊形成于中泥盆世晚期（384±6Ma）,與侵入該群的早古生代花崗巖的年齡十分接近,大致反映了哈巴河群碎屑巖沉積時代的上限,因此哈巴河群的沉積時代應在早泥盆世—中奧陶世之間。鋯石的形態和內部結構特征顯示哈巴河群的年輕碎屑鋯石類群（463～542Ma）主要為巖漿鋯石,其磨圓度較差,而且在比例上遠高于前寒武紀碎屑鋯石。上述特點與活動大陸邊緣碎屑鋯石類群分布特征完全一致,反映阿爾泰在中奧陶世至早泥盆世可能處于活動大陸邊緣構造環境。postprin

Unique Carboniferous-Permian tectonic-metallogenic framework of Northern Xinjiang (NW China): Constraints for the tectonics of the southern Paleoasian Domain

The late Paleozoic tectonic-metallogenic framework of North Xinjiang of the southern Paleoasian Domain was characterized by a serious of Carboniferous-Permian events, including: (1) late Carboniferous-Permian Chinese Altay island arc and its metamorphism, granulite in the Chinese Altay, radiolarian chert and high-pressure/ultra-high-pressure metamorphism; (2) late Carboniferous-early Permian adakites, Alaskan-type mafic-ultramafic complexes, and calc-alkaline magmatism, together with porphyry copper deposits, which occurred in the North Xinjiang; and (3) late Carboniferous ophiolite and island arc volcanic rocks located in the Tian Shan. Combined with the facts that there was no typical foreland basin, no typical collisional-type granitoid, and there were large amount of strike-slip faulting, it is suggested that in the Carboniferous-early Permian North Xinjiang was characterized by the coexistence of compression-extension-strike-slip structures with active magmatism and metallogeny. These phenomena all indicate that there were active margins during the late Carboniferous-early Permian, leading to the notion that the complicated accretionary orogeny along the southern Paleoasian Domain may have lasted to the latest Carboniferous-Permian.新疆北部晚古生代独特的构造一成矿作用以发育大量石炭纪一二叠纪构造一成矿事件为特征, 其中包括: (l) 发育于晚石炭世一二叠世的阿尔泰岛弧及其变质事件、阿尔泰麻粒岩与基性杂岩、西南天山放射虫硅质岩和高压一超高压一低压麻拉岩相变质事件; (2 )北疆发育的石炭纪(一二叠世)埃达克岩一高镁安山岩一富N d 玄武质岩组合、阿拉斯加型基性一超基性杂岩和大量的与俯冲相关的钙碱性岩浆活动与斑岩型铜矿床成矿作用; (3) 天山晚石炭世晚期蛇绿岩与岛弧火山岩等。结合北疆地区相关的前陆盆地发育不明显、碰撞型花岗岩欠发育与大量发育平行造山带大型走滑构造等现象, 可以认为新疆北部在石炭纪一二叠纪挤压一伸展一走滑并存, 岩浆活动与成矿作用活跃。这些新进展表明新疆北部在晚石炭世一二叠纪可能仍存在活动陆缘, 因此, 古亚洲洋构造域南部复杂增生造山作用最后延至晚石炭世晚期一二叠纪。published_or_final_versio

Company name identification in Chinese financial domain

2002-2003 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Selection of tuning parameters in bridge regression models via Bayesian information criterion

We consider the bridge linear regression modeling, which can produce a sparse or non-sparse model. A crucial point in the model building process is the selection of adjusted parameters including a regularization parameter and a tuning parameter in bridge regression models. The choice of the adjusted parameters can be viewed as a model selection and evaluation problem. We propose a model selection criterion for evaluating bridge regression models in terms of Bayesian approach. This selection criterion enables us to select the adjusted parameters objectively. We investigate the effectiveness of our proposed modeling strategy through some numerical examples.Comment: 20 pages, 5 figure

Modular immune-homeostatic microparticles promote immune tolerance in mouse autoimmune models

The therapeutic goal for autoimmune diseases is disease antigen-specific immune tolerance without nonspecific immune suppression. However, it is a challenge to induce antigen-specific immune tolerance in a dysregulated immune system. In this study, we developed immune-homeostatic microparticles (IHMs) that treat multiple mouse models of autoimmunity via induction of apoptosis in activated T cells and reestablishment of regulatory T cells. Specifically, in an experimental model of colitis, IHMs rapidly released monocyte chemotactic protein-1 after intravenous administration, which recruited activated T cells and then induced their apoptosis by conjugated Fas ligand on the IHM surface. This triggered professional macrophages to ingest apoptotic T cells and produce high quantities of transforming growth factor-β, which drove regulatory T cell differentiation. Furthermore, the modular design of IHMs allowed IHMs to be engineered with the autoantigen peptides that can reduce disease in an experimental autoimmune encephalomyelitis mouse model and a nonobese diabetic mouse model. This was accomplished by sustained release of the autoantigens after induction of T cell apoptosis and transforming growth factor-β production by macrophages, which promoted to establish an immune tolerant environment. Thus, IHMs may be an efficient therapeutic strategy for autoimmune diseases through induction of apoptosis and reestablishment of tolerant immune responses

From quantum fusiliers to high-performance networks

Our objective was to design a quantum repeater capable of achieving one million entangled pairs per second over a distance of 1000km. We failed, but not by much. In this letter we will describe the series of developments that permitted us to approach our goal. We will describe a mechanism that permits the creation of entanglement between two qubits, connected by fibre, with probability arbitrarily close to one and in constant time. This mechanism may be extended to ensure that the entanglement has high fidelity without compromising these properties. Finally, we describe how this may be used to construct a quantum repeater that is capable of creating a linear quantum network connecting two distant qubits with high fidelity. The creation rate is shown to be a function of the maximum distance between two adjacent quantum repeaters.Comment: 2 figures, Comments welcom

Simultaneous measurement of aqueous redox-sensitive elements and their species across the soil-water interface

The redox-sensitive elements, such as iron, manganese, sulfur, phosphorus, and arsenic, shift their speciation every millimeter (mm) across the soil-water interface in the flooded soil environments. Monitoring of element speciation at this high-resolution (HR) within the SWI is still difficult. The key challenge lies in obtaining sufficient porewater samples at specific locations along the soil gradient for downstream analysis. Here with an optimized inductively coupled plasma mass spectrometry (ICP-MS) method and a HR porewater sampler, we demonstrate mm-scale element profiles mapping across the SWI in paddy soils. High-concentrations of iron and manganese (> 10 mg/L) were measured by ICP-MS in an extended dynamic range mode to avoid signal overflow. The iron profile along the SWI generated by the ICP-MS method showed no significant difference (p < 0.05) compared to that measured independently using a colorimetric method. Furthermore, four arsenic (arsenite, arsenate, monomethylarsonic and dimethylarsinic acid), two phosphorus (phosphite and phosphate) and two sulfur (sulfide and sulfate) species were separated in 10 min by ion chromatography -ICP-MS with the NH4HCO3 mobile phase. We verified the technique using paddy soils collected from the field, and present the mm-scale profiles of iron, manganese, and arsenic, phosphorus, sulfur species (relative standard deviation < 8%). The technique developed in this study will significantly promote the measurement throughput in limited samples (e.g. 100 μL) collected by HR samplers, which would greatly facilitate redox-sensitive elements biogeochemical cycling in saturated soils

Geochemical characteristics and 40Ar- 39Ar ages of the amphibolites and gabbros in Tarlang area: Implications for tectonic evolution of the Chinese Altai

Amphibolitic and gabbroic rocks occur in Tarlang area in Chinese Altay. Amphibolites are metamorphosed products of mafic magmatic rocks (SiO 2 = 45.42% - 52.96%) and contain high Al 2O 3 (13.14% - 17.92%), Fe 2O 3 T (9.08% - 16.88%) and TiO 2 (0.82% - 3.23%) contents. The amphibolite samples show relatively flat REE patterns, without significant fractionations of REEs (La/Yb N = 1.53 - 1.79). These samples are depleted in HFSEs slightly, with slightly Ti-Nb-Ta negative anomalies, which suggest a subtle relation to subduction-related environment. The gabbroic samples (SiO 2 = 46.96% - 49.86%) have intermediate TiO 2 (0.38% - 1.89%) and relatively low K 2 O contents (K 2 O = 0.34% - 1.03%), belonging to subalkali rocks (Na 2 O > K 2 O). They have relatively high Al 2O 3 (15.0% - 20.81%), CaO (10.13% - 11.60%) and moderate MgO (7.3% - 8.3% ) contents. The gabbroic samples show two types of REE patterns. One is characterized by slight fractionation of REEs (La/Yb N = 1.10 - 1.67) and weak Eu anomalies (δEu = 1.03 - 1.10), while the other is enriched in LREE s (La/Yb N = 5.97 - 6.39), with significantly positive Eu anomalies (δEu = 1.31 - 1.44), which may reflect accumulation of plagioclase in the magma chamber. These gabbroic rocks all exhibit Ti-Nb-Ta troughs and Pb-Sr spikes, also implying a subduction-related origin. The 40Ar/ 39Ar spectrum of the gabbroic sample is simple and flat (plateau age of 266.9 ± 4.2Ma; isochron age of 261 ± 23Ma), indicating that its K-Ar isotopic system was not seriously disturbed by subsequent thermal events and may reflect the intrusion time of the gabbro. However, 40Ar- 39Ar analysis of the amphibolite give rise to a saddle-like spectrum, and its youngest plateau (297.3 ± 6.1Ma) probably reflects the last metamorphic event. The difference on age and geochemistry between the amphibolitic and gabbroic rocks implies that they probably represent different mafic magma. The protolith of amphibolites probably formed in a seamount near a subduction zone and subsequently accreated to the Altai. The gabbro exhibits subduction-releted characteristics and was coeval with transtensional movement in the Chinese Altai, probably reflecting a tectonic transition in the Permian.阿爾泰塔爾浪地區出露一些斜長角閃巖和輝長巖。其中,斜長角閃巖為基性巖漿巖變質的產物,SiO_2含量為45.42%～52.96%,具有較高的Al_2O_3(13.14%～17.92%)、Fe_2O_3~T(9.08%～16.88%)和TiO_2(0.82%～3.23%)含量。斜長角閃巖樣品稀土元素曲線比較平坦,輕重稀土元素分餾不明顯(La/Yb_N=1.53～1.79),無明顯的Nb和Ta虧損。通過野外產狀及地球化學特征分析,認為該斜長角閃巖形成于海山的構造環境。輝長巖SiO_2(46.96%～49.86%)含量稍低,TiO_2(0.38%～1.89%)變化較大,并富Al_2O_3(15.0%～20.81%)、CaO(10.13%～11.60%),具有中等至較高MgO含量(7.3%～8.3%)和相對較低的鉀含量(K_2O=0.34%～1.03%),屬亞堿性巖石系列(Na_2O>K_2O)。輝長巖呈現兩種稀土元素組成特征。一種輕重稀土分餾不明顯,配分曲線比較平坦(La/Yb_N=1.10～1.67),具有輕微的Eu正異常(δEu=1.03～1.10);另一種輕重稀土元素分餾較明顯(La/Yb_N=5.97～...published_or_final_versio

The Neurotoxicity of DOPAL: Behavioral and Stereological Evidence for Its Role in Parkinson Disease Pathogenesis

BACKGROUND: The etiology of Parkinson disease (PD) has yet to be fully elucidated. We examined the consequences of injections of 3,4-dihydroxyphenylacetaldehyde (DOPAL), a toxic metabolite of dopamine, into the substantia nigra of rats on motor behavior and neuronal survival. METHODS/PRINCIPAL FINDINGS: A total of 800 nl/rat of DOPAL (1 µg/200 nl) was injected stereotaxically into the substantia nigra over three sites while control animals received similar injections of phosphate buffered saline. Rotational behavior of these rats was analyzed, optical density of striatal tyrosine hydroxylase was calculated, and unbiased stereological counts of the substantia nigra were made. The rats showed significant rotational asymmetry ipsilateral to the lesion, supporting disruption of dopaminergic nigrostriatal projections. Such disruption was verified since the density of striatal tyrosine hydroxylase decreased significantly (p<0.001) on the side ipsilateral to the DOPAL injections when compared to the non-injected side. Stereological counts of neurons stained for Nissl in pars compacta of the substantia nigra significantly decreased (p<0.001) from control values, while counts of those in pars reticulata were unchanged after DOPAL injections. Counts of neurons immunostained for tyrosine hydroxylase also showed a significant (p=0.032) loss of dopaminergic neurons. In spite of significant loss of dopaminergic neurons, DOPAL injections did not induce significant glial reaction in the substantia nigra. CONCLUSIONS: The present study provides the first in vivo quantification of substantia nigra pars compacta neuronal loss after injection of the endogenous toxin DOPAL. The results demonstrate that injections of DOPAL selectively kills SN DA neurons, suggests loss of striatal DA terminals, spares non-dopaminergic neurons of the pars reticulata, and triggers a behavioral phenotype (rotational asymmetry) consistent with other PD animal models. This study supports the "catecholaldehyde hypothesis" as an important link for the etiology of sporadic PD