南海东部69柱粒度分维指标与气候代用指标的分形比较及其意义

南海69柱粒度数据分析表明,晚更新世以来,粒度在0.2~11μm的标度范围内具有分形特征,粒度分维值DS为1.72~2.02,平均1.84;不同时期粒度分维值明显不同,氧同位素1期(冰后期)为1.88,氧同位素2期(冰期)为1.81,温暖的冰后期粒度分维值高且变化幅度大,寒冷的冰期粒度分维值低且变化幅度小,表明粒度分维值DS对沉积物的形成环境演化具有良好的指示意义。运用R/S分析法,对69柱沉积物的粒度分维值DS、UK37法估算的表层海水古温度、浮游有孔虫的δ18O、δ13C及其转换函数计算的冬季表层海水古温度、夏季表层海水古温度、季节性温差、沉积物SiO₂、CaCO₃含量9项指标进行尺度重整分析计算,得到其时间序列分维值D_H分别为1.2855、1.1712、1.2659、1.4244、1.2719、1.2214、1.2979、1.1366、1.1609。虽然这些气候指标是用不同物理单位测量的,但运用分形分析可以对它们进行数学比较,粒度分维值DS与季节性温差二者的时间序列分维值D_H最接近,从分形理论方面进一步证实粒度分维值D_S的变化主要反映气候的冷暖变化。综合粒度分维值DS及其他气候代用指标分析,识别出南海东部全新世以来的4次突发事件。     

Sedimentary and structural evolution of the Eastern South Korea Plateau (ESKP), East Sea (Japan Sea)

The East Sea (Japan Sea) is a semi-enclosed back-arc basin that is thought to preserve a significant record of tectonic evolution and paleo-climatic changes of Eastern Asia during the Neogene. We use here 2-D regional multi-channel seismic reflection profiles and borehole data from Expedition 346 of the Integrated Ocean Drilling Program (IODP) to provide new constraints on the geological history of the Eastern South Korea Plateau (ESKP). The ESKP represents a structurally-complex basement high in the southwestern East Sea which formed during rifting of the back-arc basin. Our new observations show that the ESKP is composed of numerous horsts and grabens controlled by NE-trending normal faults. The acoustic basement is blanketed by Oligocene to recent sediments that have preferentially accumulated in topographic lows (up to 1.5 km thick) and have been cored during Expedition 346 at Site U1430 close to the southern margin of the ESKP. Seismic profiles in the ESKP reveal three units separated by regional unconformities. These seismic units closely correspond to IODP lithostratigraphic units defined at Site U1430, where biostratigraphic data can be used to constrain the timing of three main evolutionary stages of the ESKP. Stage 1 was related to rifting in the late Oligocene and middle Miocene, terminated by a regional uplift leading to an erosional phase in the middle Miocene. Stage 2 was associated with subsidence in the middle and late Miocene and uplift and accompanying erosion or non-deposition in the latest late Miocene. Stage 3 (Pliocene to present) recorded overall uniform hemipelagic-pelagic subsidence of the ESKP with short-lived tectonically-induced uplifts in the late middle Miocene and latest Miocene-early Pliocene. The three stages of evolution of the ESKP closely correlate to sedimentary changes since the Oligocene and suggest a direct control of regional/local tectonics on sedimentation patterns in the southwestern East Sea, with secondary influence of regional climatic and paleo-oceanographic processes.     

Intense reducing conditions during the last deglaciation and Heinrich events (H1, H2, H3) in sediments from the oxygen minimum zone off Goa,eastern Arabian Sea

Two sediment cores, ABP-32/GC-01R and ABP-32/GC-03 were collected at a water depth of 642 m and 1086 m off Goa from the present day Oxygen Minimum Zone (OMZ) of eastern Arabian Sea (EAS) cover time span of last 18 ka and 32 ka respectively were analysed for multi-proxy redox-sensitive elements to understand the variation in the redox conditions and factors responsible for its development.Redox-sensitive elements concentration and their normalized ratios (Mn/Al, U/Th, Mo/Al and Ce/Ce*) suggest that sediment core ABP-32/GC-01R is under more reducing conditions due to its location within the centre of OMZ compared to core ABP-32/GC-03 which is at the base of OMZ. Sediments from the EAS are of non-euxinic environments where dissolved sulfide is present but restricted to the sediment pore-waters. Lack of significant correlation (r=< 0.1) of organic carbon with U and Mo suggest that productivity may not have control on the development of reducing conditions. The lowest Mn/Al ratio, strong negative Ce/Ce* anomaly and remarkable enrichment of U/Th and Mo/Al ratios during the last deglaciation, and Heinrich events (H1, H2, H3) indicate intense reducing conditions probably due to poor ventilation by oxygen depleted bottom waters from Subantarctic Mode Waters (SAMW) - Antarctic Intermediate waters (AAIW). There is a distinct lathanide fractionation in the sediment cores where, La_(n)/Yb_(n) ratio is <1, ≈1 and >1 during the last 10 ka (Holocene), 14–10 ka (includes-Younger Dryas and Bǿlling-Allerǿd), 18–14 ka (last deglaciation) and Heinrich events suggesting less reducing, terrigenous dominated and intense reducing condition respectively.     

Lower Cretaceous lacustrine successions,North Yellow Sea Basin,eastern China: Rift basin sequence stratigraphy and stacking patterns in response to magmatic activity

A series of Mesozoic rift basins formed in eastern China were associated with magmatic activity and subduction along the Eurasia, Izanagi and Pacific plate margins. The impact of magmatic activity on lacustrine sequence development was documented with well-log and 3-D seismic data from the Jupiter Depression in the North Yellow Sea Basin. We identified key surfaces, retrogradational and progradational parasequence sets, and defined the characteristics of systems tracts and the internal sequence components for the Lower Cretaceous (K₁SQ1). A 2-D SEDPAK numerical stratigraphic forward modeling was used to further constrain sequence development in the Jupiter Depression by considering different modeling parameters and the spatial-temporal characteristics of magmatic activity. Modeling results were compared and matched with the sequence architecture observed from seismic and well interpretations. Magmatic activity impacts on the development of the K₁SQ1 sequence in the North Yellow Sea Basin include topographic variation, lake level fluctuation, and sediment supply ratios. Results suggest that magmatic upwelling uplifted the northwestern area of the Jupiter Depression and formed its slope break during the late Jurassic or early Cretaceous. Along with uplifting, relative lake level dropped sharply and lake accommodation was reduced, but with increased sediment supply. Therefore, sediment accumulated along the slope break as a lowstand systems tract. Later on, as lake level continuously rose, transgressive and highstand systems tracts were developed. The proposed stacking pattern provides an analog, and a useful model, for lacustrine sequence development in response to magmatic activities in eastern China and other rift basins of similar tectonic setting.     

2012年河北唐山M_S4.8地震前首都圈东部视应力时空变化特征

本文采用近震源Brune模式,采用国家数字测震台网数据备份中心提供的地震波形资料,测定了2011年1月至2012年5月期间首都圈东部85次ML≥2.0地震的视应力,分析了2012年4月28日河北唐山MS4.8地震前动力学参数的时空变化特征,并讨论了震源参数的标度关系。结果如下:1视应力时序变化显示,唐山MS4.8地震前首都圈东部视应力出现了明显的升高变化过程;2视应力空间分布显示,唐山MS4.8地震前,首都圈东部视应力在震源区出现了相对高值集中区。     

The local atmosphere and the turbulent heat transfer in the Eastern Himalayas

To understand the local atmosphere and heat transfer and to facilitate the boundary-layer parameterization of numerical simulation and prediction,an observational campaign was conducted in the Eastern Himalayas in June 2010.The local atmospheric properties and near-surface turbulent heat transfers were analyzed.The local atmosphere in this region is warmer,more humid and less windy,with weaker solar radiation and surface radiate heating than in the Middle Himalayas.The near-surface turbulent heat transfer in the Eastern Himalayas is weaker than that in the Middle Himalayas.The total heat transfer is mainly contributed by the latent heat transfer with a Bowen ratio of 0.36,which is essentially different from that in the Middle Himalayas and the other Tibetan regions.     

东疆天宇岩浆Cu-Ni矿床的铂族元素地球化学特征及其对岩浆演化、硫化物熔离的指示

新疆东部天宇镁铁-超镁铁杂岩体位于中天山地块的北部边缘,北侧为塔里木板块前缘活动带－沙泉子深大断裂。该杂岩体由辉长岩、辉石岩、橄辉岩、辉橄岩和橄榄岩组成,橄辉岩、辉橄岩和橄榄岩是主要的Cu、Ni矿赋矿岩相。同位素稀释法测得的铂族元素（PGE）结果显示天宇镁铁-超镁铁岩和铜镍矿石中∑PGE含量低（0.106～57.369ppb）,为原始地幔的0.01～1倍。随岩石基性程度的升高,铂族元素含量略有增高。不同矿化程度的矿石大致表现出随硫化物含量的增多,∑PGE含量增高的趋势。岩石和矿石标准化曲线均表现出正斜率,Pt都为负异常或无异常（TY602-29除外）。根据岩浆和硫化物中Ni和S含量计算,得出天宇铜镍硫化物矿床R值为348～3807,该R值范围可以形成铜镍矿床,但无法形成铂族元素矿床。Pd/Ir-Cu/Ni的投图显示原始岩浆主要为高Mg玄武岩。矿石中100％硫化物PGE含量远低于地幔5％部分熔融形成的岩浆（R＝1000时）中PGE含量,与高Mg玄武岩10％的熔融程度不符。通过模拟计算,天宇矿区存在同源但R值不同的两批岩浆。     

Tourmaline geochemistry and δ<Superscript>11</Superscript>B variations as a guide to fluid–rock interaction in the Habachtal emerald deposit,Tauern Window,Austria

Tourmalines from the Habachtal emerald deposit in the Eastern Alps formed together with emerald in a ductile shear zone during blackwall metasomatism between pelitic country rocks and a serpentinite body. Electron microprobe and secondary ion mass spectrometric (SIMS) analyses provide a record of chemical and B-isotope variations in tourmalines which represent an idealized profile from metapelites into the blackwall sequence of biotite and chlorite schists. Tourmaline is intermediate schorl-dravite in the country rock and become increasingly dravitic in the blackwall zones, while F and Cr contents increase and Al drops. Metasomatic tourmaline from blackwall zones is typically zoned optically and chemically, with rim compositions rich in Mg, Ti, Ca and F compared with the cores. The total range in δ¹¹B values is −13.8 to −5.1‰ and the within-sample variations are typically 3–5‰. Both of these ranges are beyond the reach of closed-system fractionation at the estimated 500–550°C conditions of formation, and at least two boron components with contrasting isotopic composition are indicated. A key observation from tourmaline core analyses is a systematic shift in δ¹¹B from the country rock (−14 to −10‰) to the inner blackwall zones (−9 to −5‰). We suggest that two separate fluids were channeled and partially mixed in the Habachtal shear zone during blackwall alteration and tourmaline-emerald mineralization. A regional metamorphic fluid carried isotopically light boron as observed in the metapelite country rocks. The other fluid is derived from the serpentinite association and has isotopically heavier boron typical for MORB or altered oceanic crust. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

A new jadeitite jade locality (Sierra del Convento, Cuba): first report and some petrological and archeological implications

A new jadeitite jade locality has been discovered in the serpentinite-matrix subduction mélange of the Sierra del Convento (eastern Cuba) in a context associated with tectonic blocks of garnet-epidote amphibolite, tonalitic–trondhjemitic epidote gneiss, and blueschist. The mineral assemblages of jadeitite jade and jadeite rocks are varied and include combinations of jadeite, omphacite, albite, paragonite, analcime, clinozoisite-epidote, apatite, phlogopite, phengite, chlorite, glaucophane, titanite, rutile, zircon, and quartz formed during various stages in their P–T evolution. Field relationships are obscure, but some samples made almost exclusively of jadeite show evidence of crystallization from fluid in veins. In one of these samples studied in detail jadeite shows complex textural and chemical characteristics (including oscillatory zoning) that denote growth in a changing chemical medium. It is proposed that interaction of an Al–Na rich fluid with ultramafic rocks produced Al–Na–Mg–Ca fluids of varying composition. Episodic infiltration of these fluids, as a result of episodic opening of the veins, developed oscillatory zoning by direct precipitation from fluid and after reaction of fluid with pre-existing jadeite. The latest infiltrating fluids were richer in Mg–Ca, favouring the formation of omphacite and Mg–Ca rich jadeite in open voids and the replacement of earlier jadeite by fine-grained omphacite + jadeite at 550–560°C. This new occurrence of jadeite in Cuba opens important perspectives for archeological studies of pre-Columbian jade artifacts in the Caribbean region.     

Climate deterioration in the Eastern Mediterranean as revealed by ion microprobe analysis of a speleothem that grew from 2.2 to 0.9 ka in Soreq Cave, Israel

Analysis of oxygen isotope ratios (δ¹⁸O) by ion microprobe resolves a sub-annual climate record for the Eastern Mediterranean from a Soreq Cave stalagmite that grew between 2.2 and 0.9 ka. In contrast to conventional drill-sampling methods that yield a total variation of 1.0‰ in δ¹⁸O_calcite values across our sample, the methods described here reveal up to 2.15‰ variation within single annual growth bands. Values of δ¹⁸O measured by ion microprobe vary in a regular saw-tooth pattern that correlates with annual, fluorescent growth banding where calcite grades from light to dark fluorescence. Modern records of precipitation and of cave dripwater indicate that variable δ¹⁸O_calcite values record regular seasonal differences in δ¹⁸O_rainfall modified by mixing in the vadose zone. Large differences in δ¹⁸O values measured across a single band (i.e., between the dark and light fluorescent calcite, or Δ¹⁸O_dark-light) are interpreted to indicate wetter years, while smaller differences represent drier years. Oxygen isotopes record: 1) month-scale growth increments, 2) changes in Δ¹⁸O_dark-light that represent seasonality, 3) a systematic, long-term decrease in maximum Δ¹⁸O_dark-light values, and 4) an overall increase in average δ¹⁸O_calcite values through time. These results suggest a drying of regional climate that coincides with the decline of the Roman and Byzantine Empires in the Levant region.