Spatial and ontogenetic variability in the chemical composition of juvenile common sole (Solea solea) otoliths     

S.E. Tanner  R.P. Vasconcelos  P. Reis-Santos  H.N. Cabral  S.R. Thorrold 《Estuarine, Coastal and Shelf Science》2011

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Petrological and Sr-Nd evidence bearing on Early Proterozoic magmatic events of the subcontinental mantle: Sao Francisco craton (Uaua,NE-Brazil)     

G. Bellieni  E. M. Piccirillo  R. Petrini  V. A. V. Girardi  A. B. Menezes Leal  W. Teixeira  L. R. Bastos Leal  A. De Min  P. Comin Chiaramonti  M. A. F. Tanner de Oliveira 《Contributions to Mineralogy and Petrology》1995,122(3):252-261

: Early Proterozoic (2.0–2.4 Ga), unmetamorphosed mafic dykes intrude Archean (3.1–2.7 Ga) terrains of the northern Sao Francisco craton (Uaua, NE-Brazil). The dykes are composed of evolved [atomic Mg/(Mg+Fe²)<0.6] two-pyroxene quartz tholeiites, the compositional variations of which are compatible with gabbro fractionation from different parental melts. The incompatible trace-element patterns indicate that the parental melts derived from partial melting of chemically heterogeneous garnet peridotite sources. Geochemistry and Sr-Nd isotopes imply some contamination of the Uaua dyke magma by continental crustal components during emplacement. Sr-isotopes suggest that the “uncontaminated” dykes may be related to time-integrated depleted mantle materials, while Nd-isotopes suggest mantle sources similar to the bulk Earth composition. The “uncontaminated” dykes have a positive Nb-anomaly and incompatible element contents which do not support appreciable enrichment of large ion lithophile and light rare earth elements in the source(s) throughmantle metasomatism and/or crustal components related to dehydration of a subducting slab, and an anorogenic ensialic emplacement is inferred. The Uaua dykes are chemically and isotopically distinct from the Early–Middle Proterozoic (1.9–1.7 Ga) unmetamorphosed dykes from W-Uruguay (Rio de La Plata craton) which are believed to have originated from different garnet peridotite sources. This suggests that Uaua–Uruguay compositional differences may reflect different Archean mantle differentiation and evolution of the cratonization processes. If this possibility proves to be correct, then magma genesis from various South American cratons would be by independent cratonic processes and their imprints on the subcratonic mantle. Received: 22 November 1994/Accepted: 24 July 1995  相似文献   

REPLY TO the preceding Discussion by Dominique N. Brocard of "Dimensionless Time-Drawdown Plots of Late Aquifer Test Data"     

Dominique N. Brocard  Associate 《Ground water》1989,27(1):91-91

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Geological study of sedimentary basins using SPOT data     

Nathalie Pisot  Jean-Paul Xavier  Vronique Miegebielle  Dominique Coquelet  Pierre Leymarie 《ISPRS Journal of Photogrammetry and Remote Sensing》1993,48(6)

This paper illustrates the benefits of DTMs created from SPOT images for the exploration of sedimentary basins. We chose an example located in the Ebro sedimentary basin in Spain, characterized by good outcropping conditions and slight deformations. The data used consist of a pair of SPOT panchromatic images and a SPOT XS image. The work consists of making up a 3D database, followed by interpretation of stereo pairs computed from orthoimages and the DTM. This interpretation is made on a stereoscopic desk and results in a digital file containing in the form of vectors all the observed faults and lithology. These vectors are then used to make calculations on the geometry of the objects they represent: we demonstrate that we can accurately measure layer directions and dips, sediment thicknesses and fault throws. Synthesis of perspective views made at the same time provide a good understanding of the structures and help to test their geometric consistency. Thus knowledge about relief given by DTMs helps to interpret remote detection images in 3D space, and particularly to accurately quantify the results of this interpretation.  相似文献   

Using a decadal diatom sediment trap record to unravel seasonal processes important for the formation of the sedimentary diatom signal     

Dominique Béatrice Maier  Veronika Gälman  Ingemar Renberg  Christian Bigler 《Journal of Paleolimnology》2018,60(2):133-152

Sediment trap studies and high frequency monitoring are of great importance to develop a deeper understanding of how seasonal environmental processes are imprinted in sediment signal formation. We collected whole year diatom assemblages from 2002 to 2014 with a sequential sediment trap from a varved boreal lake (Nylandssjön, Sweden) together with environmental and limnological parameters, and compared them with the corresponding diatom record of the annual laminated sediment. Our data set indicates a large year-to-year variability of diatom succession and abundance patterns, which is well reflected in the varved sediments. Specifically, Cyclotella glomerata dominated the annual sediment trap record (as well as in the corresponding sediment varves) in years with warmer air temperatures in March/April, and Asterionella formosa dominated the annual sediment assemblages as a consequence of years characterized by higher runoff before lake over-turn. Years succeeding forest clearance in the lake catchment showed marked increase in diatom and sediment flux. The DCA scores of the yearly diatom trap assemblages clearly resemble the lake’s thermal structure, which indicates that the relative abundance of major taxa seems primarily controlled by the timing of seasonal environmental events, such as above-average winter air temperature and/or autumn runoff and the current thermal structure of the lake. The high seasonal variability between environmental drivers in combination with the physical limnology leaves us with several possible scenarios leading to either an A. formosa versus C. glomerata dominated annual diatom sediment signal. With this study we highlight that short-term environmental events and seasonal limnological conditions are of major importance for interpreting annual sediment signals.  相似文献   

Geological structure and kinematics of normal faults in the Otway Basin,Australia, based on quantitative analysis of 3‐D seismic reflection data          下载免费PDF全文

Jennifer Ziesch  Chiara M. Aruffo  David C. Tanner  Thies Beilecke  Tess Dance  Andreas Henk  Bastian Weber  Eric Tenthorey  Andrea Lippmann  Charlotte M. Krawczyk 《Basin Research》2017,29(2):129-148

The Otway Basin in the south of Victoria, Australia underwent three phases of deformation during breakup of the southern Australian margin. We assess the geometry and kinematics of faulting in the basin by analysing a 3‐D reflection seismic volume. Eight stratigraphic horizons and 24 SW‐dipping normal faults as well as subordinate antithetic faults were interpreted. This resulted in a high‐resolution geological 3‐D model (ca. 8 km × 7 km × 4 km depth) that we present as a supplementary 3‐D PDF (Data S1). We identified hard‐ and soft‐linking fault connections over the entire area, such as antithetic faults and relay ramps, respectively. Most major faults were continuously active from Early to Late Cretaceous, with two faults in the northern part of the study area active until at least the Oligocene. Allan maps of faults show tectonic activity continuously waned over this time period. Isopach maps of stratigraphic volumes quantify the amount of syn‐sedimentary movement that is characteristic of passive margins, such as the Otway Basin. We show that the faults possess strong corrugations (with amplitudes above the seismic resolution), which we illustrated by novel techniques, such as cylindricity and curvature. We argue that the corrugations are produced by sutures between sub‐vertical fault segments and this morphology was maintained during fault growth. Thus, they can be used to indicate the kinematics vector of the fault movement. This evidences, together with left‐stepping relay ramps, that 40% of the faults had a small component (up to 25°) of dextral oblique slip as well as normal (dip‐slip) movement.  相似文献   

Bootstrap determination of the reliability of b-values: an assessment of statistical estimators with synthetic magnitude series     

Mendy Bengoubou-Val��rius  Dominique Gibert 《Natural Hazards》2013,65(1):443-459

We consider some practical issues of the determination of the b-value of sequences of magnitudes with the bootstrap method for short series of length L and various quantization levels $\Updelta m$ of the magnitude. Preliminary Monte Carlo tests performed with $\Updelta m = 0$ demonstrate the superiority of the maximum likelihood estimator b _MLE, and the inconsistency of the, yet often used, b _LR estimator defined as the least-squares slope of the experimental Gutenberg?CRichter curve. The Monte Carlo tests are also applied to an estimator, b _KS, which minimizes the Kolmogorov?CSmirnov distance between the cumulative distribution of magnitudes and a power-law model. Monte Carlo tests of discrete versions of the b _MLE and b _KS estimators are done for $\Updelta m = \{0.1, 0.2, 0.3 \}$ and used as reference to evaluate the performance of the bootstrap determination of b. We show that all estimators provide b estimates within 10?% error for L????100 and if a large number, n?=?2?×?10⁵, of bootstrapped sample series is used. A resolution test done with $\Updelta m = 0.1$ reveals that a clear distinction between b?=?0.8, 1.0, and 1.2 is obtained if L????200.  相似文献   

Deformation related to Miocene westward translation in the core of the Betic zone Implications on the tectonic interpretation of the Betic orogen (Spain)     

Dominique Frizon de Lamotte  Jean-Claude Guézou  Marie-Anne Albertini 《Geodinamica Acta》2013,26(4):267-281

Abstract

The Cenozoic westward motion of the Betic-Rif internal zone (“Alboran block”) between Iberia and Africa is constrained by paleogeographic considerations and by wrench faulting which affects both sides of the external zones. However, in the Alboran domain itself there was so far no evidence of significant internal deformation related to this westward displacement which was consequently consider as an en bloc” motion. Our work, in Eastern Andalucia, demonstrates that the main tectonic units building up the Betic zone should be regarded as large-scale tectonic sheets with a typical duplex style. The direction of the tectonic transport is to the West. At meso-scale, the major structures exhibit a combination of hindward and foreward dipping imbricates on the respective east and west sides of antiformal stacks or “rigid cores”. On a broader scale, the same geometric framework appears on both east and west sides of the Sierra Nevada window which we interpret as a tectonic culmination on the hangingwall of a Subbetic décollement zone. The development of this tectonics, in retrogressive metamorphic conditions, postdates the ductile deformation of the internal complexes. The morpho-tectonic relationships between the culmination of the metamorphic cores and the Neogene basins give a way to date the westward motion of the “Alboran System of Nappes” of the middle and upper Miocene.  相似文献   

Géochimie et signification géotectonique des volcanites du Cryogénien inférieur du Saghro (Anti-Atlas oriental,Maroc) / Geochemistry and geotectonic significance of Early Cryogenian volcanics of Saghro (Eastern Anti-Atlas,Morocco)     

Abdelilah Fekkak  André Pouclet  Hassane Ouguir  Hassane Ouazzani  Lakhlifi Badra  Dominique Gasquet 《Geodinamica Acta》2013,26(6):373-385

Abstract

The Early Cryogenian groups of Sidi Flah, Kelaat Mgouna and Boumalne (Saghro, Anti-Atlas, Morocco) are constituted by turbiditic deposits and interbedded lavas, accumulated in tectonic basins. At Sidi Flah, volcanics are transitional showing initial rift tholeiites (IRT) fingerprint and alkali basalts of oceanic island basalt (OIB) compositions. At Kelaat Mgouna, volcanics consist of low-Nb continental tholeiites. At Boumalne, basalts are of IRT composition. The volcanic and sedimentary formations belong to a nascent rift caused by thermal doming along a SW-NE axis, the Saghro rift. The continental break-up occurred in the early Neopro- terozoic and during the Rodinia supercontinent dislocation, within a continent called “Ibero-saharian Craton” which was in front of the West-African Craton located near the South Pole. The Saghro rift is contemporaneous to the opening of an oceanic domain represented by Central Anti-Atlas ophiolites and related to the extension of the Brazialiano Ocean. © 2001 Éditions scientifiques et médicales Elsevier SAS  相似文献   

Reply to comment on Duplex at the lateral tip of a thrust fault: the “La Cagalière” example (NE Pyrenees,France) by B. Laumonier et al     

Dominique Frizon de Lamotte  Christine Souque  Pascale Leturmy  Philippe Robion 《Geodinamica Acta》2013,26(2):183-184

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