楚雄盆地东部晚三叠世沉积环境

本文着重从野外剖面典型沉积相以及室内资料分析出发,通过对楚雄盆地东部晚三叠世古地貌、岩相、古生物、粒度以及微量元素等方面的分析,探讨盆地东部晚三叠世的沉积环境,认为晚三叠世的沉积环境从海相演变为过渡相和陆相。     

Geological evolution of the tethys belt from the atlantic to the pamirs since the LIAS

We discuss nine palinspastic geological maps (Plates 1–9), at scale, which depict the evolution of the Tethys belt from the Pliensbachian (190 Ma) to the Tortonian (10 Ma). A Present structural map (Plate 10) is shown for comparison at the same scale with the same conventions. Our reconstructions are based on a kinematic synthesis (Savostin et al., 1986), a paleomagnetic synthesis (Westphal et al., 1986) and geological compilations and analyses concerning in particular the western domain (Ricou et al., 1986), the eastern passive margins (Kazmin et al., 1986a), the eastern active margins (Kazmin et al., 1986b), the Black Sea-Caspian Sea basins (Zonenshain and Le Pichon, 1986) and the ophiolites (Knipper et al., 1986).     

Palaeozoic history of the Armorican Massif: Models for the tectonic evolution of the suture zones

The Armorican Massif (western France) provides an excellent record of the Palaeozoic history of the Variscan belt. Following the Late Neoproterozoic Cadomian orogeny, the Cambro-Ordovician rifting was associated with oceanic spreading. The Central- and North-Amorican domains (which together constitute the core of the Armorica microplate) are bounded by two composite suture zones. To the north, the Léon domain (correlated with the “Normannian High” and the “Mid-German Crystalline Rise” in the Saxo-Thuringian Zone) records the development of a nappe stack along the northern suture zone, and was backthrusted over the central-Armorican domain during the Carboniferous. To the south, an intermediate block (“Upper Allochthon”) records a complex, polyorogenic history, with an early high-temperature event followed by the first generation of eclogites (Essarts). This intermediate block overthrusts to the north the Armorica microplate (Saint-Georges-sur-Loire), to the south: (i) relics of an oceanic domain; and (ii) the Gondwana palaeomargin. The collision occurred during a Late Devonian event, associated with a second generation of eclogites (Cellier).     

New seismic images of the crust in the central Trans-Hudson Orogen of Saskatchewan

A reprocessing program to enhance the correlation between the surface geology and the seismic data has been completed for seismic line 9 (eastern 100 km) and line 10 in the central region of the Trans-Hudson Orogen of Saskatchewan, Canada. The new seismic images through lateral continuity of reflectivity provide sufficient detail to resolve the discrepancy between the low-dipping, layer-parallel and dextral-reverse nature of the Sturgeon-Weir shear zone (line 9) observed in the field and its steeply dipping (apparent) normal displacement character interpreted on the basis of the initial processing. Furthermore, the new interpretation provides a strong confirmation of the role of Pelican Thrust as a major detachment zone — the main `sole thrust' — along which juvenile allochthons have been carried across the Archaean microcontinental block. The images are also refined enough to suggest: (a) a boundary within the Pelican Thrust between its internal and external suites; (b) a possible boundary separating a lower (older?) Archaean basement from its upper (younger?) counterpart; and (c) sub-Moho events (M2) which reveal possible involvement of the upper mantle in the collisional tectonic process in addition to the well defined Moho (M1) which probably represents the youngest of the post-collisional detachments.     

On the consistency of proposed models for the Pyrenees with the structure of the eastern parts of the belt

The structure of the eastern Pyrenees consists mainly of south-directed thrusts involving basement and cover rocks. An antiformal stack developed by the piling up of basement thrust sheets which outcrop in the Axial zone. These structures account for a thin-skinned thrust model rather than a vertical fault model in which the Axial zone would be essentially autochthonous, and the North-Pyrenean fault the axial plane of a fan thrust system. New data from the Eastern Pyrenees and the thin-skinned model suggest that(1) the structure east of the Pedraforca nappe is similar to that of the Central Pyrenees; (2) the cover rocks of the South-Pyrenean units and of the Axial zone-after restoration—built up a northwards-thickening prism consistent with the existence of a unique Pyrenean sedimentary basin during Mesozoic time; (3) the Axial zone is only a complex antiformal stack developed as a part of South-Pyrenean system related to the Paleogene thrusting-tectonics. The Axial zone palaeogeographic area had no special meaning during Mesozoic time.     

长江中下游地区九瑞矿集区邓家山花岗闪长斑岩的地球化学与成因研究

邓家山是长江中下游成矿带九瑞矿集区西北部的一处矽卡岩型Cu-Au-Mo矿床.矿区与成矿关系密切的岩体为花岗闪长斑岩.本文通过锆石SHRIMP U-Pb定年确定,该岩体侵位于早白垩世早期(138.2±1.8Ma).常微量元素分析结果表明,邓家山花岗闪长斑岩具有埃达克质岩的地球化学特征,表现为高Sr(＞650×10~(-6))、Ba(＞700×10~(-6)),低Y(＜12×10~(-6)),Yb(＜1×10~(-6)),Nb(＜10×10~(-6)),Ta(＜0.7×10~(-6)),富集轻稀土而强烈亏损重稀土(LREE/HREE=12.2～13.5).邓家山花岗闪长斑岩的~(87)Sr/~(86)Sr,为0.7068～0.7071,ε_(Nd)(t)为-2.7～-2.3,Nd同位素两阶段模式年龄T_(2DM)为1.13Ga～1.15Ga.锆石的Hf同位素分析结果表明,~(176)Ht/~(177)Hf值为0.282475～0.282539,计算的ε_(Hf)(t))值为-5.2～-7.5,Hf同位素两阶段模式年龄T2DM为1.52Ga～1.67Ga.全岩ε_(Nd)(t)与锆石ε_(Hf)(t))之间出现了较为明显的Nd-Hf同位素解耦.根据以上特征,我们认为邓家山花岗闪长斑岩是壳幔相互作用的产物,即增厚下地壳拆沉并部分熔融,岩浆在上升过程中又与地幔橄榄岩发生大规模混染.     

准噶尔盆地南缘郝家沟剖面下侏罗统三工河组辫状河三角洲沉积特征

对准噶尔南缘郝家沟剖面下侏罗统三工河组的沉积相与层序地层特征进行了详细的研究,确认三工河组发育辫状河三角洲沉积。辫状河三角洲包括辫状河三角洲平原亚相、辫状河三角洲前缘亚相和前辫状河三角洲亚相。辫状河三角洲前缘亚相又可进一步划分为水下分流河道、水下分流河道间、席状砂和河口坝等微相类型。三工河组辫状河三角洲沉积除一些层位的辫状河道沉积物颗粒较粗外,主体沉积物以砂岩、粉砂岩和泥岩为主,为砂质辫状河三角洲。运用高分辨率层序地层学基准面旋回划分原理,将三工河组划分为2个中期基准面旋回,下部中期基准面旋回又可划分为4个短期基准面旋回,上部中期基准面旋回发育不完整。     

Seismic imaging of the transitional crust across the northeastern margin of the South China Sea

Crustal structure across the passive continental margin of the northeastern South China Sea (SCS) is presented based on a deep seismic survey cooperated between Taiwan and China in August 2001. Reflection data collected from a 48-hydrophone streamer and the vertical component of refraction/reflection data recorded at 11 ocean-bottom seismometers along a NW–SE profile are integrated to image the upper (1.6–2.4 km/s), lower (2.5–2.9 km/s), and compacted (3–4.5 km/s) sediment, the upper (4.5–5.5 km/s), middle (5.5–6.5 km/s) and lower (6.5–7.5 km/s) crystalline crust successively. The velocity model shows that the thickness (0.5–3 km) and the basement of the compacted sediment are strongly varied due to intrusion of the magma and igneous rocks after seafloor spreading of the SCS. Furthermore, several volcanoes and igneous rocks in the upper/middle crust (7–10 km thick) and a high velocity layer (0–5 km thick) in the lower crust of the model are identified as the ocean–continent transition (OCT) below the lower slope in the northeastern margin of the SCS. A thin continent NW of the OCT and a thick oceanic crust SE of the OCT in the continental margin of the northeastern SCS are also imaged, but these transitional crusts cannot be classified as the OCT due to their crustal thickness and the limited amount of the volcano, the magma and the high velocity layer. The extended continent, next to the gravity low and a sag zone extended from the SW Taiwan Basin, may have resulted from subduction of the Eurasian Plate beneath the Manila Trench whereas the thick oceanic crust may have been due to the excess volcanism and the late magmatic underplating in the oceanic crust after seafloor spreading of the SCS.     

On the origin of the western Mediterranean Sea basins

This is a report of a symposium organized by the Netherlands Commission for the Upper Mantle Project. The data relative to the generation of the western Mediterranean Sea basins, presented during this symposium, are summarized in the Appendix.

Several modes of origin have been discussed:

1. (1) the basins are remnants of a former larger ocean;

2. (2) they are formed in the wake of drifting continental blocks;

3. (3) by an erosion and denudation of a continental crust;

4. (4) by an upheaval and later subsidence of an ocean floor; or

5. (5) by sub crustal erosion of a continental crust.

It is concluded that, although many data are in agreement with the drift model, this process cannot have been the sole agent in the generation of the basins.     

The influence of the Evros River on the recent sedimentation of the inner shelf of the NE Aegean Sea

The transboundary Evros River discharges into the Alexandroupolis Gulf, located in the inner shelf of the northeastern Aegean Sea, where it has formed an extended delta. Grain-size and mineralogical analyses of five sediment cores, collected in the subaqueous delta, provide the following information about recent sedimentation processes in the northeastern part of the Aegean shelf: (a) river mouth deposits, consisting of coarse-grained sediments, are mainly deposited in front of the active mouth, whilst some sandy material is expected to be transported alongshore by nearshore currents; (b) delta front deposits are characterised by fine-grained sediments that include evidence of human activities which have taken place, in a more intense way, since the 1950s; and (c) prodelta deposits are represented by almost uniform riverine mud that cover the pre-existed relict sands of the shelf, indicating also the limit (some 15 km to the SW) of the influence of riverine sedimentation on the seabed of the inner shelf of the Alexandroupolis Gulf.     

Structural assemblies of the Vladimir-Vyatka dislocation zone and the position of the Puchezh-Katunki Crater,East European Platform

The Puchezh-Katunki (PK) structural unit is situated in the Middle Volga region of the central East European Platform (EEP). It is expressed as a system of complex dislocations and a meteoritic crater with a central uplift. Based on the results of structural study, the attributes of its long evolution have been revealed. Four deformation stages have been established: Hercynian (1) fold-nappe and (2) trancpressional deformations, (3) formation of the Early Jurassic impact crater and the related system of radial-concentric faults, and (4) low-amplitude tectonic reactivation of Hercynian faults during the Kimmerian-Alpine stage of evolution. In general, the PK structural unit is localized in the most strained segment of the Vladimir-Vyatka Dislocation Zone, which separates the largest structural domains of the EEP. This is a long-lived zone, which developed cyclically beginning from Paleoproterozoic collisional events and up to the Kimmerian-Alpine stage of reactivation. Such a direct impact to the cluster of concentrated deformations in one of the largest tectonic zones of the EEP seems unlikely. Nevertheless, available evidence, including the estimated stress related to the impact effect (up to 50 GPa) and its decrease with depth, does not rule out the meteoritic origin of the PK structural unit.     

The role of tectonic flow of crustal material in the formation of the Sea of Japan and the Sea of Okhotsk

Based on the concept of tectonic delamination of the lithosphere, we revealed that the Sea of Japan and the Sea of Okhotsk were formed as a result of the tectonic flow of crustal material. The intermittent southward movement of southwestern Japan (Late Cretaceous–Cenozoic) along the eastern Japanese leftlateral strike-slip fault zone resulted in the formation of paired structures: back-arc extensional (Central Japan rift) and frontal compressional (South Japan imbricate–thrust belt) structures. The Sea of Okhotsk was formed in a similar tectonic setting: South Okhotsk rift (back-arc extensional structure) and Kamuikotan–Susunai compressional belt (frontal imbricate-thrust structure). Synchronous extension, compression, and strike-slip movements suggest that the tectonic flow of crustal material played a critical role in the formation of the Sea of Japan and the Sea of Okhotsk.     

A high-resolution speleothem proxy record of the Late Glacial in the European Alps: extending the NALPS19 record until the beginning of the Holocene

Previous research has shown that speleothems from the northern rim of the European Alps captured submillennial-scale climate change during the last glacial period with exceptional sensitivity and resolution, mimicking Greenland ice-core records. Here we extend this so-called NALPS19 record across the Late Glacial using two stalagmites which grew continuously into the Holocene. Both specimens show the same high-amplitude δ¹⁸O signal as Greenland ice cores down to decadal resolution. The start of the warming at the onset of the equivalent of Greenland Interstadial (GI) GI-1e at 14.66 ± 0.18 ka agrees with the North Greenland Ice Core Project (NGRIP) (14.64 ± 0.28 ka) and comprised a temperature rise of about 5–6 °C. The transition from the equivalent of GI-1a into the equivalent of Greenland Stadial (GS) GS-1 (broadly equivalent to the Younger Dryas) commenced at 13.02 ± 0.13 ka which is consistent with NGRIP (12.80 ± 0.26 ka) within errors. The onset of the Holocene started at 11.78 ± 0.14 ka (11.65 ± 0.10 ka at NGRIP) and involved a warming of about 4–5 °C. In contrast to δ¹⁸O, δ¹³C values show no response to (sub)millennial climate shifts due to strong rock-buffering and only record a long-term trend of soil development starting with the rapid warming at 14.7 ka.     

有机化合物分子体积的加和性--Ⅰ.烃类的官能团的拓扑体积

液态的碳氢化合物分子体积等于官能团拓扑体积之和,即服从于加和性原则。在不同的烃类中相同的官能团有十分接近的体积贡献。官能团的拓扑体积,V（CH₂）=27.24Å3,V（CH₃）=55.11Å₃,V（-CH=CH₂）=70.12Å3,V（-CH=CH-）=40.98Å3,V（-C≡CH）=51.58Å3,V（-C≡C-）=21.18Å3,V（H）端部=29.32Å3。V（C₆H₅-）=120.08Å3,V（-C₆H₄-）=89.92Å3,V（-C₆H₄=）=61.51Å3。液态碳氢化合物的分子体积还可以用如下公式来表示。V=k+13.89·C+6.67HÅ3）K为液体常数,烷、烯和炔K=40,苯同系物K=25,环烷烃K=15。C、H分别是分子中C和H的原子数。     

Geomorphological evolution of the River Loukkos estuary around the Phoenician city of Lixus on the Atlantic Littoral of Morocco

The ancient city of Lixus, today situated on a hill on the right bank of the River Loukkos, 4km from the coast, was founded on the shore of a brackish lagoon that was sheltered from Atlantic storms. This geographical context provided the city with one of the best Phoenician harbors and abundant fishing resources, and allowed access to the Gharb cattle farming resources and cereal production systems. In this study, the historical evolution of the Loukkos estuarine environment is reconstructed through geomorphological and sedimentological analyses, combined with cartographic, archaeological, and geographical data. The outcomes reveal the progressive infilling of the estuarine lagoon of Lixus and its transformation into the current estuary and floodplain. The recent history of this estuary records four successive stages: (1) an initial stage associated with the maximum Holocene marine transgression (5500 to 5320 cal. yr B.P.) that reached the interior of the estuary; (2) a sheltered brackish tidal lagoon stage in Phoenician and Roman times; (3) a period of progressive infilling of the estuarine lagoon, from late Roman times to the Middle Ages (11th to15th centuries); (4) a period of rapid expansion of intertidal marshes (17th to 19th centuries) that saw the formation of the modern estuarine plain and meandering channel system (20th century). © 2009 Wiley Periodicals, Inc.     

Chandler wobble of the poles as part of the nutation of the atmosphere-ocean-Earth system

The paper presents calculated spectra of El Niño Southern oscillation (ENSO) indices. The ENSO spectra have components with periods that are multiples of the Earth’s free (1.2 years) and forced (18.6 years) nutation periods. Analysis of a 41-year series of exciting functions for the atmospheric angular momentum confirms the existence of such periodicity. Nutation waves responsible for the El Niño phenomena in the ocean, the Southern oscillation in the atmosphere, and the presence of subharmonics of the Chandler period (1.2 years) and superharmonics of the lunar period (18.6 years) in the ENSO spectra are described. A model for the nonlinear nutation of the Earth-ocean-atmosphere system is constructed. In this model, the ENSO, acting at frequencies of combinational resonances, excites the Chandler wobble of the Earth’s poles. At the same time, this wobble interacts with the nutation motions of the atmosphere and World Ocean.     

Geochemical structure of the Early Carboniferous volcanic complexes of the Southern Urals

In this paper, the concept of a geochemical structure (Yaroshevskii, 2004) was applied to describe chemical variations in the Early Carboniferous volcanic complexes and their distribution over the tectonic zones of the Southern Urals and Transuralian region in order to clarify the geodynamic settings of their formation. The cluster analysis of a geochemical dataset including 325 analyses of volcanic rocks from the Magnitogorsk, Southern Ural, Transuralian, and Valer’yanovskii tectonic zones allowed us to reduce the geochemical diversity of rocks to eight large geochemical groups. Based on average compositions, these geochemical groups (clusters) can be classed with the following rocks: (1) low-K tholeiitic basalts, (2) high-Ti subalkaline basalts, (3) high-Al subalkaline basalts, (4) subalkaline andesites, (5) subalkaline rhyolites, (6) Na subalkaline rhyolites, (7) potassic subalkaline rhyolites, and (8) high-Al potassic trachyandesibasalts. The distribution of these clusters in tectonic zones of the Southern Urals and Transuralian makes it possible to organize these complexes into four groups. The first group includes a differentiated series from high-Ti subalkaline basalts to sodic subalkaline rhyolites with the predominance of aluminous subalkaline basalts and subalkaline andesites. This group is most widespread in the Magnitogorsk and Valer’yanovskii zones. The second group corresponds to a differentiated series from low-K basalts to Na subalkaline rhyolites with a strong prevalence of high-Ti subalkaline basalts and less abundant aluminous subalkaline basalts. This group is widespread in the Eastern Ural zone. The third group includes subalkaline andesites and rhyolites with subordinate ultrapotassic rhyolites and trachyandesibasalts, which compose the Uya-Novoorenburg suture. The fourth group comprises high-Ti subalkaline basalts occurring in the Transuralian zone. Such a distinct distribution of the geochemical types of volcanic rocks is well consistent with concepts on the formation of the Southern Ural volcanic belts at the East European paleocontinent margin in a Californian-type setting. The Valer’yanovskii belt was formed at the active margin of the Kazakhstan paleocontinent.     

Structure and evolution of the passive margin of the eastern tethys

An extensive passive margin was formed in the Triassic along the periphery of Arabia, including the Tauric carbonate platform. This event is related to the opening of the Mesozoic Tethys when a number of microcontinents split off from Gondwana. Triassic extension and continental rifting resulted in the formation of a structural pattern which is uniform from the Dinarides to Oman. It includes the following elements:

1. (1) shelf,

2. (2) continental slope,

3. (3) deep basin probably with a floor of attenuated sialic crust,

4. (4) inner carbonate platform. In the Jurassic-Cretaceous stable conditions prevailed, influenced only by eustatic oscillations of the sea level. Turbidites accumulated on the continental rise while cherts and radiolarites were deposited in the deep basins (Hawasina, Pichakun, Antalya, Pindus) below the CCD level. Sedimentation on the shelf was controlled by north-northeast transverse tectonic elements which also continued across the passive margin, dividing it into a number of segments. Collision with an island arc led to obduction of the oceanic crust, deformation of the passive margin and overthrusting of its sedimentary cover onto the Arabian shelf. Obduction and deformation lasted for about 10 m.y. and created a new tectonic pattern with concentric structural zones surrounding the Arabian promontory.

These zones include:

1. (1) the flysch basin—a remnant of the closing Tethys;

2. (2) an uplift—a site of periodical emergence and erosion, corresponding to the frontal part of the ophiolitic nappes;

3. (3) the Border furrow—a depocenter of low-energy calcareous marls,

4. (4) the Arabian shield constantly emerged during the Tertiary. Tectonic deformation of these zones caused by the collision of Arabia with Eurasia began prior to the Early Miocene and it is still going on.

Data on Afghanistan demonstrate that its central part (the Gelmend-Argandab and Kabul blocks) belonged during the Paleozoic and Early Mesozoic to the continental shelf of India.     

Factors controlling the mineralogy and geochemistry of the recent surface sediments of the Kalloni Gulf,Lesvos Island,Greece

Detailed chemical and mineralogical data are presented for 37 samples of surface sediments collected from the Kalloni gulf, (eastern half), Lesvos island, northern Greece. The sediments are largely carbonate-rich muds, though near the eastern and northern coast of the gulf higher proportions of biogenic and lithogenic sands and gravels occur. The main minerals are quartz, feldspar (andesine), clay minerals (montmorillonite, illite, Kaolinite) and the carbonate minerals (calcite, Mg-calcite, aragonite). The mathematical method of factor analysis was applied in order to explain the mineralogical and geochemical variations. These variations can be interpreted in terms of variations in provenance and depositional environment. Six factors were produced accounting for 83.6 % of the total data variance: (a) a Si-Al-Na-K-Ti-Rb-Ba-Y-Zr factor controlled by clays and detrital minerals such as feldspars and zircon opposed by a CaCO₂-Cu-Sc-Sr-La association (carbonate, minerals), (b) an organic carbon factor (C-Fe-Ce-Zn-Rb-Ni-Y-Nb), (c) a Fe-Mg-Cr-Ni factor representing control by peridotite, (d) a Ce-Nd-Fe-Ni-Zn-La factor controlled by silicate minerals, (e) a Al-Fe-Ti-P-V factor controlled by chlorite amphiboles or pyroxenes of volcanic or basaltic intrusions, (f) a Mn-Fe-Zn-factor controlled by iron-manganese oxides. Similarities in trace element composition among Kalloni gulf bottom sediments, and source lithologies indicate that the trace elements are derived from the adjacent landmasses. The AI/Ti ratio of the sediments is consistent with the terrigenous nature of sendimentation in the Kalloni gulf.