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1.
The vegetational history of the penultimate glacial period, Marine Isotope Stage (MIS) 6 (c. 185–135 ka), has remained relatively unexplored. Here we present a new record from the Ioannina basin, north‐west Greece, which constitutes the highest‐resolution terrestrial pollen record for this interval produced to date. It shows that the vegetation history of MIS 6 in this region can be divided into two parts: an early period (185–155 ka) with pronounced oscillations in tree population extent, and a later period (155–135 ka) with much smaller tree populations and subdued oscillations. This pattern is analogous to the MIS 3/MIS 2 division during the last glacial in the same sequence, although the early part of MIS 6 had larger Pinus populations and fewer temperate trees relative to the equivalent interval in MIS 3. This implies cooler and wetter conditions, which is somewhat counterintuitive given the high summer insolation during MIS 6e, but is in line with other palaeoclimatic evidence from the Mediterranean. Comparison with North Atlantic records suggests that despite the absence of pronounced iceberg discharges during MIS 6, North Atlantic millennial‐scale variability had a significant downstream impact on tree populations in north‐west Greece. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
2.
通过设计特异性引物,采用PCR扩增的方法对厚壳贻贝足腺细胞cDNA文库进行筛选,共克隆得到14条厚壳贻贝mcofp3的cDNA序列和8条mcofp6的cDNA序列,并对其基因序列及推导的氨基酸序列进行了序列比对和变异位点初步分析。结果表明,14条mcofp3cDNA序列分属于厚壳贻贝mcofp3家族的两个亚家族,其成熟肽序列变异相对活跃;而8条mcofp6 cDNA序列并无明显的亚家族划分,序列相对保守。本次实验所获得的mcofp cDNA序列初步显示了厚壳贻贝足丝蛋白家族基因的分子多样性,为将来深入了解厚壳贻贝足丝蛋白的分子多样性机制以及在此基础上开发相关的新型生物黏附剂奠定了基础。 相似文献
3.
This paper presents an example of application of the double solid reactant method (DSRM) of Accornero and Marini (Environmental
Geology, 2007a), an effective way for modeling the fate of several dissolved trace elements during water–rock interaction. The EQ3/6 software
package was used for simulating the irreversible water–rock mass transfer accompanying the generation of the groundwaters
of the Porto Plain shallow aquifer, starting from a degassed diluted crateric steam condensate. Reaction path modeling was
performed in reaction progress mode and under closed-system conditions. The simulations assumed: (1) bulk dissolution (i.e.,
without any constraint on the kinetics of dissolution/precipitation reactions) of a single solid phase, a leucite-latitic
glass, and (2) precipitation of amorphous silica, barite, alunite, jarosite, anhydrite, kaolinite, a solid mixture of smectites,
fluorite, a solid mixture of hydroxides, illite-K, a solid mixture of saponites, a solid mixture of trigonal carbonates and
a solid mixture of orthorhombic carbonates. Analytical concentrations of major chemical elements and several trace elements
(Cr, Mn, Fe, Ni, Cu, Zn, As, Sr and Ba) in groundwaters were satisfactorily reproduced. In addition to these simulations,
similar runs for a rhyolite, a latite and a trachyte permitted to calculate major oxide contents for the authigenic paragenesis
which are comparable, to a first approximation, with the corresponding data measured for local altered rocks belonging to
the silicic, advanced argillic and intermediate argillic alteration facies. The important role played by both the solid mixture
of trigonal carbonates as sequestrator of Mn, Zn, Cu and Ni and the solid mixture of orthorhombic carbonates as scavenger
of Sr and Ba is emphasized.
相似文献
Luigi Marini (Corresponding author)Email: |
4.
JEAN‐FRANÇOIS GHIENNE FLAVIA GIRARD JULIEN MOREAU JEAN‐LOUP RUBINO 《Sedimentology》2010,57(5):1175-1198
Climbing dune‐scale cross‐statification is described from Late Ordovician paraglacial successions of the Murzuq Basin (SW Libya). This depositional facies is comprised of medium‐grained to coarse‐grained sandstones that typically involve 0·3 to 1 m high, 3 to 5 m in wavelength, asymmetrical laminations. Most often stoss‐depositional structures have been generated, with preservation of the topographies of formative bedforms. Climbing‐dune cross‐stratification related to the migration of lower‐flow regime dune trains is thus identified. Related architecture and facies sequences are described from two case studies: (i) erosion‐based sandstone sheets; and (ii) a deeply incised channel. The former characterized the distal outwash plain and the fluvial/subaqueous transition of related deltaic wedges, while the latter formed in an ice‐proximal segment of the outwash plain. In erosion‐based sand sheets, climbing‐dune cross‐stratification results from unconfined mouth‐bar deposition related to expanding, sediment‐laden flows entering a water body. Within incised channels, climbing‐dune cross‐stratification formed over eddy‐related side bars reflecting deposition under recirculating flow conditions generated at channel bends. Associated facies sequences record glacier outburst floods that occurred during early stages of deglaciation and were temporally and spatially linked with subglacial drainage events involving tunnel valleys. The primary control on the formation of climbing‐dune cross‐stratification is a combination between high‐magnitude flows and sediment supply limitations, which lead to the generation of sediment‐charged stream flows characterized by a significant, relatively coarse‐grained, sand‐sized suspension‐load concentration, with a virtual absence of very coarse to gravelly bedload. The high rate of coarse‐grained sand fallout in sediment‐laden flows following flow expansion throughout mouth bars or in eddy‐related side bars resulted in high rates of transfer of sands from suspension to the bed, net deposition on bedform stoss‐sides and generation of widespread climbing‐dune cross‐stratification. The later structure has no equivalent in the glacial record, either in the ancient or in the Quaternary literature, but analogues are recognized in some flood‐dominated depositional systems of foreland basins. 相似文献
5.
乌兰诺尔井田位于内蒙古自治区东北部,含煤地层主要为白垩系下统巴彦花组,6号煤是区内唯一可采煤层,其显微组分镜质组含量为85.2%~91.0%,惰质组含量为2.0%~13.4%,壳质组在2%以下。测试分析表明6号煤属中灰、低—中高硫、高热值褐煤,其挥发分高,化学反应性好,燃烧时速度快,反应充分,是很好的动力燃料,适用于火力发电。 相似文献
6.
7.
利用直接电位法,采用标准加入的方式测定了不同浓度和温度条件下,LiPF6水溶液中的F-浓度,同时考察了碱处理对LiPF6水解的影响,并采用电导率测定结果进行了验证.实验表明,LiPF6能够在水中稳定存在,且几乎不受碱度和温度的影响. 相似文献
8.
6-O-羧甲基壳多糖的细胞毒性效应研究 总被引:5,自引:0,他引:5
Chen Xiguang 《中国海洋大学学报(自然科学版)》2000,30(Z1):221-224
采用溶血试验和细胞毒性试验研究6 -O-羧甲基壳多糖的细胞毒性效应,结果表明:1% 浓度的6-O-羧甲基壳多糖对红细胞溶 血率小于5%,说明该材料无溶血现象。以手术缝合线和500μg/mL的苯酚为对照研究不同分 子量的6-O-羧甲基壳多糖分别在1000μg/mL和2000μg/mL浓度下对大白鼠皮肤成纤维细胞 生长的影响,经过2d,4d,7d细胞培养,细胞增殖率均大于100%,说明该材料对成纤维细胞 无毒性效应且对大白鼠皮肤成纤维细胞有促进生长的作用,分子量越小促生长作用越强,随 着培养时间延长促生长作用亦增强。此研究在一定程度上证明,6-O-羧甲基壳多糖作为医 用生物材料在细胞毒性方面是安全的。 相似文献
9.
探讨了1597年10月6日(明万历二十五年八月二十六日)地震的烈度特征,地震伴随的湖震和火山喷发,以及地震类型与规模.结果表明, 1597年10月6日地震为可能发生在ldquo;珲春——汪清深震区rdquo;的一次Mge;8深源地震;地震在中国东部地区产生了广泛的湖震,其多种形态可与1775年葡萄牙里斯本地震产生的湖震比拟;地震触发了望天鹅火山的一次中小规模爆发式喷发,其地点在中国吉林省长白县境内. 相似文献
10.
Five mobile digital seismic stations were set up by the Earthquake Administration of Yunnan Province near the epicenter of the main shock after the Ning’er M6.4 earthquake on June 3, 2007. In this paper, the aftershock sequence of the Ning’er M6.4 earthquake is relocated by using the double difference earthquake location method. The data is from the 5 mobile digital seismic stations and the permanent Simao seismic station. The results show that the length of the aftershock sequence is 40km and the width is 30km, concentrated obviously at the lateral displacement area between the Pu’er fault and the NNE-trending faults, with the majority occurring on the Pu’er fault around the main shock. The depths of aftershocks are from 2km to 12km, and the predominant distribution is in the depth of 8~10km. The mean depth is 7.9km. The seismic fault dips to the northwest revealed from the profile parallel to this aftershock sequence, which is identical to the dip of the secondary fault of the NE-trending Menglian-Mojiang fault in the earthquake area. There are more earthquakes concentrated in the northwest segment than in the southeast segment, which is perhaps related to the underground medium and faults. The depth profile of the earthquake sequence shows that the relocated earthquakes are mainly located near the Pu’er fault and the seismic faults dip to the southwest, consistent with the dip of the west branch of the Pu’er fault. In all, the fault strike revealed by earthquake relocations matches well with the strike in the focal mechanism solutions. The main shock is in the top of the aftershock sequence and the aftershocks are symmetrically distributed, showing that faulting was complete in both the NE and SW directions. 相似文献