Petrology,U/Pb dating and (C-O) stable isotope constraints on the source and evolution of the adakite-related Mezcala Fe-Au skarn district,Guerrero, Mexico     

Gilles?LevresseEmail author  Eduardo?González-Partida  Alejandro?Carrillo-Chavez  Jordi?Tritlla  Antoni?Camprubí  Alain?Cheilletz  Dominique?Gasquet  Etienne?Deloule 《Mineralium Deposita》2004,39(3):301-312

  相似文献   

Corrigendum to “Revision of the Upper Cretaceous Rudists from Northwestern Peru” [South American Earth Science 17 (2004) 39–48]     

Jean Philip  Etienne Jaillard   《Journal of South American Earth Sciences》2005,19(4)

  相似文献   

Latest Precambrian to Early Cambrian U–Pb zircon ages of augen gneisses from Calabria (Italy), with inference to the Alboran microplate in the evolution of the peri-Gondwana terranes     

Francesca Micheletti  Pierre Barbey  Annamaria Fornelli  Giuseppe Piccarreta  Etienne Deloule 《International Journal of Earth Sciences》2007,96(5):843-860

In situ U–Pb dating of zircons from five samples of Calabrian augen gneisses shows that their protoliths are Latest Precambrian to Early Cambrian in age (562 ± 15, 547 ± 7, 540 ± 4, 539 ± 16 and 526 ± 10 Ma), and contain Archaean (3.1 Ga), Palaeoproterozoic (1.7–2.4 Ga) and Neoproterozoic (0.6–0.9 Ga) inheritance. Geochemical signature of augen gneisses is typical of high-K calc-alkaline post-collisional magmatism. Their Sr–Nd isotopic compositions [0.7093 < (⁸⁷Sr/⁸⁶Sr)_i < 0.7139; −3.2 < ɛ_Nd(t) < −5.4; 1.5 < T _DM < 1.7 Ga] indicate the involvement of a crustal component in significant proportions. The Calabrian augen gneisses have, therefore, to be distinguished from the orthogneisses of Sardinia and northern Algeria, and from the porphyroids of Sicily, which are Middle Ordovician. By contrast, the Calabrian augen gneisses show a close similarity to the Pan-African post-collisional granitoids of the northern edge of the West African craton (e.g. the Moroccan Anti-Atlas). This suggests a peri-Gondwana origin and corroborates previous palaeogeodynamic reconstructions attributing the Alboran microplate to the northern margin of the West African craton.  相似文献   

Behaviour of Li and its isotopes during metasomatism of French Massif Central lherzolites     

Christiane Wagner  Etienne Deloule 《Geochimica et cosmochimica acta》2007,71(17):4279-4296

Li behaviour and distribution in the mantle were investigated by ion microprobe in situ measurements on co-existing olivine (ol), orthopyroxene (opx), clinopyroxene (cpx) and amphibole (amp) in xenoliths from the French Massif Central. The fertile spinel lherzolites of this study record increasing degrees of mantle metasomatism, from unmetasomatised anhydrous samples through cryptically metasomatised samples to highly metasomatised amphibole-rich samples. In anhydrous lherzolites, Li is preferentially incorporated into olivine (1.1-1.4 ppm, average values) compared to pyroxenes (0.2-0.9 ppm). The hydrous samples clearly show enrichment of Li in ol (1.5-5.0 ppm), opx (1.1-2.4 ppm) and cpx (2.4-5.4 ppm), while amphibole incorporates less Li than the co-existing phases (0.8-1.3 ppm). Average δ⁷Li values range from +7.6 to +14.5‰ in ol, from 5.1 to +13.7‰ in opx and from 8.8 to +10.3‰ in cpx from the anhydrous lherzolites. A layered peridotite sample (Sdi) shows higher Li content in all phases, with lighter isotopic composition in opx and cpx (−0.6 and −2‰ average δ⁷Li values, respectively). In the hydrous lherzolites average δ⁷Li values both overlap and extend beyond these ranges in ol (up to 17.5 ‰) and in opx (up to 22.9‰), and vary widely in cpx (−2.7 to +9.7‰). Low δ⁷Li values are observed in some opx (−10.4‰) and cpx (−13‰) from sample Sdi, and in cpx from three hydrous samples (from −9.7 to −5.3‰). The different anhydrous phases from the hydrous samples show large intra-grain variations in Li isotopic ratios (e.g., up to 18‰) compared to the same phases from the anhydrous samples (mostly less than 6‰), excepting sample Sdi which has up to 20.4‰ variation in cpx. Similar to the anhydrous silicates, amphiboles show a wide variation of δ⁷Li values on the intra-grain scale (2-27‰). These variations are interpreted to result from fractionation processes during metasomatism by a silicate melt undergoing compositional changes as it percolates through and reacts with the peridotite phases. Thus Li abundances and isotopic in situ measurements are useful for tracing metasomatic processes but the heterogeneities observed in the samples preclude any identification of a specific mantle source by its Li signature.  相似文献   

Andean geodynamics: main issues and contributions from the 4th ISAG, Göttingen     

Etienne Jaillard  Grard Hrail  Tony Monfret  Gerhard Wrner 《Tectonophysics》2002,345(1-4)

  相似文献   

碧溪岭岩体中石榴橄榄岩的锆石显微结构及离子探针定年   总被引：7，自引：1，他引：7  

吴元保  陈道公  程昊  Etienne Deloule  夏群科 《高校地质学报》2001,7(3):356-362

对碧溪岭岩体中石榴橄榄岩的锆石进行了BSE和CL显微结构分析，并在此基础上用离子探针进行了锆石微区U－Pb定年。锆石CL图像显示其有明显的核边结构，核部具岩浆锆石，边部是变质增生锆石的特征。结合锆石的外形特征认为，边部的变质锆石是在超高压变质作用中重结晶形成的。离子探针分析结果在一致曲线图中构成不一致线，得到上下交点 年龄分别为824±39Ma和254±38Ma。结合CL图像认为上交点824±39Ma的年龄代表其原岩形成年龄，下交点254±38Ma为基超高压变质作用的年龄。另有少量较年龄的捕虏晶锆石，可能来自岩浆上升过程中同化混染的围岩。  相似文献   

变质锆石拉曼光谱研究--以大别造山带为例   总被引：5，自引：0，他引：5  

程昊  陈道公  Etienne Deloule  吴元保 《矿物学报》2002,22(4):353-358

对大别山的道士冲辉石岩、双河榴辉岩和碧溪岭石榴橄缆岩的锆石进行了激光拉曼探针，阴极发光（CL）观察和U、Th等微量元素的微区分析及U－Pb同位素测定，发现锆石拉曼光谱波数和半高宽都能指示其蜕晶化程度，但对于高度蜕晶化锆石，波数已经不再完全适用，而只能通过其特征谱峰半高宽来确定。碧溪岭石榴橄榄岩锆石微区微量元素和拉曼探针分析发现，半高宽和Th/U比正相关，这是由岩浆锆石在变质过程中不同程度的固态重结晶作用造成的，其可能曾经遭受过约220Ma的热事件扰动。双河榴辉岩锆石则可能遭受了流体参与下的变质重结晶作用的影响。锆石重结晶作用是变质岩中锆石年龄和化学组成变化的主要原因。  相似文献   

The Rocourt Tephra, a widespread 90–74 ka stratigraphic marker in Belgium     

Andr Pouclet  Etienne Juvign  Stphane Pirson 《Quaternary Research》2008,70(1):105-120

A new study of the stratigraphy and composition of the Rocourt Tephra is performed at five sites in Belgium and brackets the age of the tephra between 90.3 and 74 ka. The volcanic glass grains have a typical shape of phreatomagmatic eruption products. A large set of tephra minerals were analyzed, namely clinopyroxene, orthopyroxene, amphibole, and Cr-spinel. The compositions of these minerals have been compared with the lava xenocrysts, megacrysts, and phenocrysts of the proximate Eifel volcanic province for which the origin has been determined (mantle xenoliths, high-pressure cumulates, and middle- to low-pressure magmatic phases). This allowed us to determine the likely origin of the tephra minerals. The Rocourt Tephra source could be a West Eifel volcano that was fed by a deep-seated magma batch rich in high- to middle-pressure minerals.  相似文献   

Society Awards 2017          下载免费PDF全文

Etienne Nel 《New Zealand geographer》2018,74(1):57-57

  相似文献   

Seismic stratigraphy and paleogeographic evolution of Fairway Basin,Northern Zealandia,Southwest Pacific: from Cretaceous Gondwana breakup to Cenozoic Tonga–Kermadec subduction          下载免费PDF全文

Pierrick Rouillard  Julien Collot  Rupert Sutherland  Francois Bache  Martin Patriat  Samuel Etienne  Pierre Maurizot 《Basin Research》2017,29(Z1):189-212

We present the first comprehensive seismic‐stratigraphic analysis of Fairway Basin, which is situated on the rifted continent of Zealandia in the Tasman Sea, southwest Pacific, between Australia and New Caledonia. The basin is 700 km long, 150 km wide, and has water depths of 500–3000 m. We describe depositional architecture and paleogeographic evolution of this basin. Basin formation was concurrent with two tectonic events: (i) Cretaceous rifting during eastern Gondwana breakup and (ii) initiation and Cenozoic evolution of Tonga–Kermadec subduction system to the east of the basin. To interpret the basin history we compiled and interpreted 2D seismic‐reflection profiles and make correlations with DSDP boreholes and the geology of New Caledonia. Five seismic‐stratigraphic units were defined. The deepest and oldest unit, FW3, folded and faulted can be correlated with volcaniclastic sediments and magmatic rocks in New Caledonia that are associated with Mesozoic Gondwana margin subduction. Alternatively, given the basin location 200–300 km west of New Caledonia and inboard of the ancient plate boundary, the unit could have formed as Gondwana intra‐continental basin with no known correlative. The overlying unit FW2b records syn‐rift deposition, probably associated with Cretaceous Gondwana breakup. Subaerial erosion supplied terrigenous sediment into the deltas in the northern part of the basin, as suggested by the truncation surfaces on the basement highs and sigmoid reflector geometries within unit FW2b respectively. Above, unit FW2a records post‐rift sedimentation and passive subsidence as the Tasman Sea opened and the Fairway Basin drifted away from Australia. Subsidence led to the flooding of the basement highs and burial of wave‐cut surfaces. Eocene compressive deformation resulted in minor folding and tilting within the Fairway Basin and was associated with the formation of many diapiric structures. The top of unit FW2 is an extensive unconformity that is associated with erosion and truncation on surrounding ridges. Above this unconformity, unit FW1b is interpreted as a turbidite system sourced from topography created during the Eocene tectonic event, which we interpret as being related to Tonga–Kermadec subduction initiation. Pelagic carbonate sedimentation is now prevalent. Unit FW1a has progressively draped the basin during Oligocene to Pleistocene subsidence. Many small volcanic cones were erupted during this final phase of subsidence, either as a delayed consequence of subduction initiation, or related to Tasmantid and Lord Howe hotspot trails. The northern Fairway Ridge remains close to sea level and its reef system continues to supply carbonate detrital sediments into the basin, most likely during sea‐level lowstands. Fairway Basin contains a nearly continuous record of tectonic and paleoclimatic events in the southwest Pacific since Cretaceous time. Its paleogeographic history is a key piece in the puzzle for understanding patterns of regional biodiversity in the southwest Pacific.  相似文献