Geologica Acta最新文献

{"title":"The structure of the South-Central-Pyrenean fold and thrust belt as constrained by subsurface data","authors":"J. Muñoz, Joana Mencos, E. Roca, N. Carrera, Ò. Gratacós, O. Ferrer, O. Fernández","doi":"10.1344/GEOLOGICAACTA2018.16.4.7","DOIUrl":"https://doi.org/10.1344/GEOLOGICAACTA2018.16.4.7","url":null,"abstract":"The interpretation of the available seismic lines of the South-Central-Pyrenean fold and thrust belt, conveniently tied with the exploration wells, define the main structural features of this realm of the Pyrenees. In particular, they define the geometry and areal extension of the autochthonous foreland underneath the sole thrust. The mapping ofseveral selected structural lines brings constraints for the structural interpretation of the South-Central Pyrenees, including the cut-off lines between selected stratigraphic horizons of the autochthonous foreland and the branch line between basement-involved thrust sheets and the sole thrust. The thrust salient which characterizes at surface the geometry of the South-Pyrenean fold and thrust belt contrasts with the linear trend of these structural lines at subsurface. This salient has been the result of a secondary progressive curvature developed since Middle Eocene times by thrust displacement gradients during verthrusting of the South-Pyrenean thrust sheets above a Paleogene autochthonous sequence. Displacement gradients resulted from the uneven distribution of weak salt layers, mostly the Triassic and the Upper Eocene ones. The minimum amount of South-directed displacement from early MiddleEocene times to Late Oligocene is 52km, which would be significantly higher if internal shortening by folding and cleavage/fracture development as well as hanging-wall erosion is added.","PeriodicalId":55107,"journal":{"name":"Geologica Acta","volume":"16 1","pages":"439-460"},"PeriodicalIF":1.5,"publicationDate":"2018-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41612133","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"First evidence of paleoearthquakes along the Carboneras Fault Zone (SE Iberian Peninsula): Los Trances site","authors":"E. Masana, Ximena Moreno, E. Gràcia, R. Pallas, M. Ortuño, R. López, O. Gómez‐Novell, P. Ruano, H. Perea, P. Štěpančíková, G. Khazaradze","doi":"10.1344/GEOLOGICAACTA2018.16.4.8","DOIUrl":"https://doi.org/10.1344/GEOLOGICAACTA2018.16.4.8","url":null,"abstract":"Seismogenic faults that have not produced historical large earthquakes remain unnoticed and, thus, are dangerously left out from seismic hazard analyses. The seismogenic nature of the Carboneras Fault Zone, a left-lateral strikeslip fault in the Eastern Betic Shear Zone (southeastern Spain), has not been fully explored to date in spite of having a morphological expression equivalent to the Alhama de Murcia Fault, a seismogenic fault in the same tectonic system. This study provides the first paleoseismic evidence of the seismogenic nature of the CarbonerasFault Zone, based on the analysis of 3 trenches at Los Trances site, on the northwestern edge of the La Serrata Range. Cross cutting relationships and numerical dating, based on radiocarbon, thermoluminescence and U-series, reveal a minimum of 4 paleoearthquakes: Paleoearthquake1 (the oldest) and Paleoearthquake2 took place after 133ka, Paleoearthquake3 occurred between 83–73ka and Paleoearthquake4 happened after 42.5ka (probably after 30.8ka), resulting in a maximum possible average recurrence of 33ka. This value, based on a minimum amount of paleoearthquakes, is probably overestimated, as it does not scale well with published slip-rates derived from offset channels or GPS geodetical data. The characterization of this fault as seismogenic, implies that it should be considered in the seismic hazard analyses of the SE Iberian Peninsula.","PeriodicalId":55107,"journal":{"name":"Geologica Acta","volume":"16 1","pages":"461-476"},"PeriodicalIF":1.5,"publicationDate":"2018-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44265130","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The extent of penetrative Pyrenean deformation in the Ebro foreland Basin: Magnetic fabric data from the eastern sector","authors":"J. Parés, D. Anastasio","doi":"10.1344/GEOLOGICAACTA2018.16.4.3","DOIUrl":"https://doi.org/10.1344/GEOLOGICAACTA2018.16.4.3","url":null,"abstract":"We studied Cenozoic sedimentary rocks in the NE Ebro foreland Basin using the Anisotropy of Magnetic Susceptibility (AMS) as a proxy for grain preferred orientation. Our new data, in combination with existing results, reveal that penetrative strain by layer-parallel shortening extends well beyond the Pyrenean thrust-wedge front into the Ebro foreland Basin, challenging the concept of the location of “deformation front” in the Southern Pyrenees. Penetrative strain, as revealed by the magnetic fabrics, seems to reach larger distances into the Ebro foreland Basin where stiffer layers constitute the main detachment level, whereas to the East strain dissipates closer to the deformation front when the detachment is mostly due to salt deposits.","PeriodicalId":55107,"journal":{"name":"Geologica Acta","volume":"16 1","pages":"375-390"},"PeriodicalIF":1.5,"publicationDate":"2018-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47526018","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Deformation pattern around the Conejera fault blocks (Asturian Basin, North Iberian Margin)","authors":"P. Granado, S. Tavani, N. Carrera, J. Muñoz","doi":"10.1344/GEOLOGICAACTA2018.16.4.2","DOIUrl":"https://doi.org/10.1344/GEOLOGICAACTA2018.16.4.2","url":null,"abstract":"The Asturian Basin is located on the coastline of the North Iberian Margin. This basin is dissected by long-lived E-, NE- and NW-striking faults that delineate a series of extensional fault blocks that became shortened during the Upper Cretaceous to Cenozoic Alpine convergence. In the Conejera cove, the NE-striking and SE-dipping Conejera Fault displays a remarkable example of contractional deformation, promoted by the mechanical contrast within the Lower to Middle Jurassic stratigraphic series. Field observations and structural analysis carried out in this study reveal: i) a first system of orthogonal cross-joints oblique to the Conejera Fault and other major onshore boundary faults, ii) a second system of meso-extensional faults parallel to the Conejera Fault, and developed by the reactivation and linkage of the orthogonal cross-joints and iii) a series of contractional folds, thrusts and pressure solution with a predominant NE to ENE trend. Observed relationships and structural analysis suggest an obliquity between the here inferred direction of the Late Jurassic-Early Cretaceous stretching ( i.e. about N015E) and the onshore boundary faults, whereas the contractional structures are broadly parallel to the NE-striking Conejera Fault and suggest a roughly SSE- to SE-oriented Alpine convergence.","PeriodicalId":55107,"journal":{"name":"Geologica Acta","volume":"16 1","pages":"357-373"},"PeriodicalIF":1.5,"publicationDate":"2018-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44556507","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"3D structure of subsurface thrusts in the eastern Jaca Basin, southern Pyrenees","authors":"P. Labaume, A. Teixell","doi":"10.1344/GEOLOGICAACTA2018.16.4.9","DOIUrl":"https://doi.org/10.1344/GEOLOGICAACTA2018.16.4.9","url":null,"abstract":"This paper presents a new model of the subsurface structure of the eastern Jaca flexural basin of the west-central southern Pyrenees, by means of subsurface structural maps and four new balanced cross-sections. The study is based on the interpretation of a set of publicly available seismic reflection profiles tied to deep exploration well logs, which constitute a unique database in the southern Pyrenees associated to the gas discovery of the Serrablo field. Investigation of the deep basin structure highlights strong mechanical-stratigraphic contrasts between basement, a competent Upper Cretaceous-Eocene carbonate sequence in the deep basin and a weak infill of Eocene to lower Miocene synorogenic clastic deposits. These contrasts promote the occurrence of various decollement levels and a decoupled style of deformation between intervals of different competence. A contour map for the top of basement reveals a complex structure with lateral variations of the number of thrusts and the displacement on these and local transverse elements. Between the Gavarnie thrust at the southern edge of the Axial Zone and the Guarga thrust at the leading edge of the \u0000basement thrust system, three main other basement thrusts are defined below the north-eastern Jaca Basin, from South to North the Fiscal, Yesero and Broto thrusts. In the Meso-Cenozoic sedimentary cover, two low-angle thrusts are mapped in the subsurface across the Upper Cretaceous-Eocene carbonates: i) the deep Oturia thrust, connected upsection to the emerging Oturia thrust known at the surface, and ii) the deep Jaca thrust, drilled by the Serrablo wells, and connected to the emerging Jaca thrust and Yebra de Basa anticline through a zone of disharmonic deformation. The deduced subsurface geometrical relationships are consistent with the connection of the Gavarnie and Broto basement thrusts to the Priabonian-Rupelian Oturia and Jaca thrusts while the younger Yesero, Fiscal and Guarga basement thrusts emerge at the South Pyrenean thrust front of the Sierras Exteriores, active until the early Miocene. This study highlights the complex structural pattern that characterizes the deep structure of the South Pyrenean basin and the role of disharmonic deformation that challenges the resolution of the deeper thrust system without the help of seismic profiles.","PeriodicalId":55107,"journal":{"name":"Geologica Acta","volume":"16 1","pages":"477-498"},"PeriodicalIF":1.5,"publicationDate":"2018-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47181488","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Weld kinematics of syn-rift salt during basement-involved extension and subsequent inversion: Results from analog models","authors":"M. Roma, O. Ferrer, K. McClay, J. Muñoz, E. Roca, Ò. Gratacós, P. Cabello","doi":"10.1344/GEOLOGICAACTA2018.16.4.4","DOIUrl":"https://doi.org/10.1344/GEOLOGICAACTA2018.16.4.4","url":null,"abstract":"Scaled analog models based on extensional basins with synrift salt show how basement topography exerts a control factor on weld kinematics during the extension and inversion phases. In the case of basement-involved extension, syn-rift salt thickness differences may lead to variable degrees of extensional decoupling between basement topography and overburden, which in turn have a strong impact on the development of salt structures. With ongoing extension and after welding, the basin kinematics evolves toward a coupled deformation style. The basin architecture of our experimental results record the halokinetic activity related to growing diapirs and the timing of weld formationduring extension. Moreover, the structures that result from anysubsequent inversion of these basins strongly depends on the inherited welds and salt structures. While those basins are uplifted,the main contractional deformation during inversion is absorbed by the pre-existing salt structures, whose are squeezed developing secondary welds that often evolve into thrust welds. The analysis of our analog models shows that shortening of diapirs is favored by: i) basement topography changes that induce reactivation of primary welds as thrust welds; ii) reactivation of the salt unit as a contractional detachment and iii) synkinematic sedimentation during basin inversion. Finally, in this article, we also compare two natural examples from the southern North Sea that highlight deformation patterns very similar to those observed in our analog models.","PeriodicalId":55107,"journal":{"name":"Geologica Acta","volume":"16 1","pages":"391-410"},"PeriodicalIF":1.5,"publicationDate":"2018-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46996811","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Review of the Ediacaran-Lower Ordovician (pre-Sardic) stratigraphic framework of the Eastern Pyrenees, southwestern Europe","authors":"M. Padel, S. Clausen, J. Álvaro, Josep María Casas Tuset","doi":"10.1344/GEOLOGICAACTA2018.16.4.1","DOIUrl":"https://doi.org/10.1344/GEOLOGICAACTA2018.16.4.1","url":null,"abstract":"The Ediacaran-Lower Ordovician successions exposed in the Eastern Pyrenees are updated and revised based on recent U-Pb zircon radiometric ages, intertonguing relationships of carbonate-dominated strata, and onlapping patterns marking the top of volcano-sedimentary complexes. A stratigraphic comparison with neighbouring pre-Variscan outcrops from the Montagne Noire (southern French Massif Central) and Sardinia is related to i) the absence of Cadomian deformation close to the Ediacaran-Cambrian boundary interval; ii) the presence of an episodic, Cadomian-related, acidic-dominant volcanism related to carbonate production punctuating the Ediacaran-Cambrian transition, similar to that recorded in the northern Montagne Noire; and iii) the lack of Guzhangian (Late Cambrian Epoch 3) regressive shoal complexes present in the Montagne Noire and probably in Sardinia.","PeriodicalId":55107,"journal":{"name":"Geologica Acta","volume":"16 1","pages":"339-355"},"PeriodicalIF":1.5,"publicationDate":"2018-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41417072","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Structure of an intraplate fold-and-thrust belt: The Iberian Chain. A synthesis","authors":"J. Guimerà","doi":"10.1344/GEOLOGICAACTA2018.16.4.6","DOIUrl":"https://doi.org/10.1344/GEOLOGICAACTA2018.16.4.6","url":null,"abstract":"The Iberian Chain is a complex intraplate fold-and-thrust belt resulting from the convergence between the Eurasian, Iberian and African plates during the late Eocene to the Miocene. The main trend of its contractional structures is NW-SE, but E-W, NE-SW and N-S-trending structures are also present. The boundaries of the chain with its surrounding foreland basins are always thrusts. The North-Iberian Thrust separates the chain from the Ebro Basin to the North, while the Serrania de Cuenca Thrust makes the SE boundary of the chain, separating it from the Tajo Basin and La Mancha foreland areas. Between these thrusts, the contractional structure is basement-involved, while South of the Serrania de Cuenca Thrust only Mesozoic and Cenozoic rocks are involved in the thrust-system, detached in the evaporitic Triassic materials. Two parts can be differentiated considering the major structure of the chain. The western and central areas hold two major anticlinoriums separated by the Almazan Synclinorium. East of the Teruel Depression, E-Wstriking N-verging thrusts in the North, and NW-SE-striking S-verging thrusts in the center and South are the dominant structures. The crust thickened during the Cenozoic contraction generating a mean crustal thickening of about 5km. The horizontal shortening obtained from cross-sections is 32km, and from a density-gravity section of 57.5km. These two values may be considered end values. The relief of the Iberian Chain has a strong areal coincidence with the contractional structures and the thickened crust, indicating that they are genetically related.","PeriodicalId":55107,"journal":{"name":"Geologica Acta","volume":"16 1","pages":"427-438"},"PeriodicalIF":1.5,"publicationDate":"2018-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41595615","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Integrated approach for zonation of a mid-Cenomanian carbonate reservoir in a sequence stratigraphic framework","authors":"R. Jodeyri-Agaii, H. Rahimpour-Bonab, V. Tavakoli, Rahim Kadkhodaie-Ilkhchi, Mohammadreza Yousefpour","doi":"10.1344/GEOLOGICAACTA2018.16.3.5","DOIUrl":"https://doi.org/10.1344/GEOLOGICAACTA2018.16.3.5","url":null,"abstract":"The mid-Cenomanian Mishrif Formation (Fm.) is considered as one of the most important rudist-bearing reservoir horizons in the Sirri Oil Fields of the Persian Gulf. Due to the general heterogeneity of carbonate reservoirs, the use of an integrated approach is helpful for investigating porosity and permeability distribution along with recognizing controlling pore system factors in the reservoir. Thus, for the reservoir characterization of the Mishrif Fm., an integrated approach including facies analysis, diagenetic history and sequence stratigraphic analysis is considered. Detailed petrographic studies showed a total of eight microfacies and seven facies belts, related to inner ramp to the basin of a homoclinal carbonate ramp. Humid climatic condition and tectonic activity, associated with eustatic sea-level fluctuations during the mid-Cretaceous, led to meteoric diagenesis of the Mishrif carbonates during subaerial exposures (mid-Cenomanian and Cenomanian-Turonian disconformities). General diagenetic overprints and modifications include micritization, cementation, dissolution, compaction, dolomitization, pyritization and fracturing. Considering this reservoir in the sequence stratigraphic framework reveals that the reservoir zones development is basically related to the Cenomanian–Turonian sequence boundary, recognized in the three studied wells, and also to the mid-Cenomanian boundary, identified only in one well. In addition, pore system properties were inspected by differentiation of Hydraulic Flow Units (HFUs) within the reservoir. The identified flow units, based on their capability for fluid flow, can be classified into four main rock types with very high- (HFUD), high- (HFUC), medium- (HFUB) and low-quality (HFUA). Accordingly, this study shows that the main part of the Mishrif Reservoir is affected by diagenetic processes related to subaerial exposures, resulting in zones with higher storage capacity and fluid flow rates. So, the study of depositional and diagenetic characteristics of the Mishrif carbonates in the sequence stratigraphy framework is essential to unravel the reservoir heterogeneity, and to describe the reservoir zones and their distribution in the field and regional scale. In addition, observed changes in the thickness of hydrocarbon column are attributed to the different location of the studied wells on the anticline structures, which show a tilted oil-water contact with a slope to the North.","PeriodicalId":55107,"journal":{"name":"Geologica Acta","volume":"16 1","pages":"321-337"},"PeriodicalIF":1.5,"publicationDate":"2018-08-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43201557","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Geochemistry and Petrogenesis of metabasites from the Gol-e-Gohar Complex in southern Sanandaj-Sirjan metamorphic zone, South of Iran; Evidences for crustal extension and magmatism at early Palaeozoic","authors":"H. Fatehi, H. Ahmadipour","doi":"10.1344/GEOLOGICAACTA2018.16.3.4","DOIUrl":"https://doi.org/10.1344/GEOLOGICAACTA2018.16.3.4","url":null,"abstract":"In Gol-e-Gohar metamorphic Complex from south-eastern Sanandaj-Sirjan metamorphic zone (Kerman province, Iran), there are two types of metabasites contain layered metamorphosed lava flows and the younger meta-gabbros. The protoliths formed in the Paleozoic era and were metamorphosed during the early Cimmerian orogenic phase in the late Triassic, under temperatures of 640–680oC and pressures of ~7–10.5kbar (amphibolite facies). These rocks are garnet-bearing amphibolites, garnet free amphibolites and metamorphosed gabbros. Many mineralogical and chemical aspects of these metabasites are similar, although the layered metabasites show tholeiitic and the meta-gabbros depict alkaline affinities. Evidences such as whole rock geochemical characteristics, Sr and Nd isotopic data, (143Nd/144Ndinitial=0.511913–0.512067; eNd550Ma=-0.31–2.68), relatively flat patterns of chondritenormalized Rare Earth Elements and multi-elemental diagrams, the enrichment in TiO2 (average content ~2.16) and high Zr/Y ratios (3–8), indicate that all of Gol-e-Gohar metabasites are formed in an extentional intracontinental rift zone from tholeiitic to alkaline magmas. The data suggest that the paren magmas could derived by low degrees of partial melting of spinel-lherzolite sources in subcontinental lithospheric mantle. These evidences confirm the existence of extentional environments in southern part of the Sanandaj-Sirjan metamorphic zone in the Paleozoic era, when large extensional depressions developed in the Sanandaj-Sirjan metamorphic zone and underlying asthenosphere ascent and partially melted during this time. Gradually, thick sequences of continental detritic sediments and tholeiitic lava flows accumulated in these troughs. Subsequent magmatic event in the area characterizes by emplacement of alkaline gabbro intrusions. At the early Cimmerian orogeny, these sedimentaryigneous rocks associations metamorphosed and the Gol-e Gohar metabasites formed.","PeriodicalId":55107,"journal":{"name":"Geologica Acta","volume":"16 1","pages":"293-319"},"PeriodicalIF":1.5,"publicationDate":"2018-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46867492","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}