Tectono-sedimentary Evolution Research Articles

The Grès Singuliers of the Mont Blanc region (France and Switzerland): stratigraphic response to rifting and crustal necking in the Alpine Tethys

The Grès Singuliers unit represents an anomalous occurrence of a siliciclastic-dominated sedimentary system typifying a restricted geographic area around the Mont Blanc massif. Deposited during Early Jurassic rifting, this unit was influenced by the tectonic processes responsible for its development. This contribution integrates and reconciles sedimentological, stratigraphic and tectonic data and discusses the tectono-sedimentary evolution of the Mont Blanc basement and its autochthonous sedimentary cover. Based on depositional facies, a petrographic and detrital zircon provenance analysis, we propose that the Grès Singuliers unit is mainly derived from erosion of the local basement and pre-rift sedimentary cover. Furthermore, recognition of Jurassic cataclasites and black gouges capping the Mont Blanc basement confirms the hypothesis that the Mont Blanc domain formed an extensional core complex. The source to sink relationship between the Mont Blanc detachment system and the Grès Singuliers unit, as well as timing and location within the Alpine rift system, allows us to interpret this unit as the syn-tectonic sedimentary response to crustal necking, responsible for the onset of localized severe crustal/lithospheric thinning in the European margin of the Alpine Tethys rift system. The main result of this study was to show that the exhumation and uplift of basement during crustal/lithospheric necking produced a new source area for clastic sedimentary systems. Therefore, the local occurrence of a siliciclastic unit similar to the Grès Singuliers along passive margins may be symptomatic of necking zones in other rift systems.

Interacción entre vulcanismo, tectónica y sedimentación en una plataforma carbonatada somera: Ejemplo en el Tethys occidental (Jurásico Medio, sureste de la Cordillera Ibérica)

En el sureste de la Cordillera Ibérica (España) existen una serie de afloramientos de rocas volcánicas origi­nadas por erupciones submarinas, principalmente de tipo volcanoclástico, interestratificadas en las sucesiones carbonatadas del Jurásico Inferior y Medio. La cartografía geológica de los afloramientos de rocas volcánicas revela que se encuentran alineados a lo largo de tres elementos de debilidad cortical bien definidos (zonas de falla de Teruel, de Caudiel y de Alcublas), originados probablemente por fracturas relacionadas con la apertura y expansión del Tethys Ligur y del Tethys Alpino. En este trabajo se presentan los resultados del estudio de la evolución tectonosedimentaria de un ambiente submarino somero afectado por la presencia de una acumulación volcánica que tuvo lugar en el Jurásico Medio (límite Aaleniense‒Bajociense). Se trata del afloramiento volcánico de Caudiel, que es el más suroriental de todos los afloramientos localizados en uno de los tres elementos de debilidad estructural mencionados: la Zona de Falla de Caudiel. La presencia de un relieve positivo en el fondo de la plataforma, ya de por sí bastante somera, condiciona la sedimentación carbonatada, muy sensible a la pro­fundidad, hasta el punto de llegar a inducir cambios significativos de facies con respecto a otras áreas cercanas o de impedir la sedimentación. Los movimientos episódicos del substrato generaron una topografía irregular y cambiante a lo largo del tiempo, con tasas variables de hundimiento y levantamiento en diferentes áreas. El aflo­ramiento de Caudiel constituye un buen ejemplo fósil de interacción entre varios factores (vulcanismo, tectónica y sedimentación) en plataformas carbonatadas someras, en las que los cambios de acomodación y las tasas de sedimentación parecen estar subordinadas a perturbaciones tectónicas de carácter local.

Tectono-sedimentary evolution of the Late Ediacaran to early Cambrian trough in central Sichuan Basin, China: New insights from 3D stratigraphic forward modelling

Several conceptual models have been proposed on the tectono-sedimentary evolution of the Late Ediacaran to early Cambrian trough in the central Sichuan Basin, China. However, none of them has adequately accounted for the regional stratigraphic architecture, palaeogeography and sedimentary facies revealed by recent petroleum exploration in a quantitative manner. This study presents the first attempt to simulate the tectono-sedimentary evolution of the trough in three dimensions using a process-based stratigraphic forward modelling approach. The model simulates the tectono-sedimentary evolution and indicates that: (1) the trough started from a prototype of small sag during the Early Ediacaran Doushantuo stage; (2) it began to expand progressively during the Late Ediacaran Dengying stage, and (3) the trough was eventually filled up in the early Cambrian. The tectono-sedimentary evolution differs in the southern and central-northern parts of the study area, and also inside and outside of the trough. The developing mechanism of the trough is due primarily to a combination of regional extension, differential subsidence and especially differential carbonate growth or deposition. Differential subsidence and sea level changes resulted in relatively deep water in the central and western parts of the study area during the Deng-2 and Deng-3 deposition. Slope to basinal facies were deposited with relatively slow rates. The depositional rate of the deep-water sediments in the area could not catch up with the rate of tectonic subsidence. This had led the central and western parts of the study area to finally become “starved” and developed into a deep trough with steep slopes developed on both flanks of the trough. In contrast, in the eastern part of the study area shallow water carbonates were persistently developed with relatively high growth or depositional rates, maintaining a shallow-water carbonate depositional setting. Platform facies were well developed throughout the Dengying stage, although the area experienced a similar tectonic evolution history as the central and western parts with a slower subsidence rate. The new tectono-sedimentary model may offer some new insights for future hydrocarbon exploration in the Sichuan Basin.

Oligocene evolution of the outermost continental margin in response to breakup and early spreading of the South China Sea

Preliminary results of the International Ocean Discovery Program (IODP) Expeditions 367/368/368X have confirmed the unique opening mechanism of the South China Sea differentiating from that of the Atlantic Ocean. However, its detailed evolution history and controlling factors spanning from the early Oligocene breakup to the early Miocene steady spreading are still unclear. Here, we conducted sedimentary, geochemical, and mineralogical analyses to a special sequence recovered at IODP Expedition 367 Site U1499 to reconstruct the Oligocene tectono-sedimentary evolution of the outermost margin. Our results indicate that a Mesozoic arc-related source primarily provided terrigenous clastics during rifting and early spreading periods in submarine canyon and ridge-flank slope environments, respectively. Late Neoproterozoic to early Paleozoic epimetamorphic fragments were enriched along with continental breakup and decreased upward in the overall retrograding sequence. Biogenous and hydrogenous contributions increased gradually and became dominant after the establishment of a stable pelagic deep basin in the earliest Miocene. Provenance and environment features demonstrate that the South China Sea was characterized by a special early spreading stage during which the outermost margin was relatively unstable and developed gravity flows to transport clastics to Site U1499. Two retrograding events occurred simultaneously with mid-ocean ridge jumps at ca. 27.0 Ma and ca. 23.0 Ma implying the tectono-sedimentary evolution of the distal margin was influenced by mantle activities.

Evolution of sedimentation pattern in a continental rift basin of India, between the Late Triassic and the early Middle Jurassic: Tectonic and climatic controls

The spatial and temporal pattern of sedimentation in a rift basin is a result of complex interplay between tectonically induced vertical crustal movement and climatic condition. Though the conceptual and numerical models for tectono-sedimentary evolution of half grabens are available, the stratigraphic arrangement of lithofacies produced by the environments on hangingwall block is poorly documented till date. Additionally, the stratigraphic record resulting from the interactions between the hangingwall processes and those of the basin trough is less known. The purpose of this work is to delineate the tectonic and climatic factors controlling the distribution of sedimentary environments from the stratigraphic architecture of a Late Triassic to Early Jurassic syn-rift strata of a continental half-graben of India. This work also aims to characterize the deposits formed in the transitional environments that occur in between the fluvial system of the hangingwall dip slope and the lacustrine system at the basin trough. This work involves a detailed sedimentological study including facies analysis and palaeocurrent analysis.The studied syn-rift sediments record i) a changeover from axial to transverse fluvial system in the end of Triassic, ii) transition from fluvial to lake marginal environment in the Early Jurassic and iii) evolution of an extensive palustrine system in the Middle Jurassic. The corresponding changes in lithological and geochemical characters for the first change points towards incresed tectonic movement along the main boundary fault that caused the progradation of the hangingwall fans towards the basin trough. Later changes can be attributed to the reconfiguration of the sedimentary environments due to increase in aridity that influenced the introduction of coarse clastics to the basin.

Role of structural inheritance and salt tectonics in the formation of pseudosymmetric continental rifts on the european margin of the hyperextended Mauléon basin (Early Cretaceous Arzacq and Tartas Basins)

Arzacq and Tartas were two Cretaceous basins developing in the Bay of Biscay as secondary depocentres in the larger Aquitaine Basin. They belong to an Albian rift system, where recent studies have stressed the role of simple-shear thinning on the genesis of regional asymmetric basins. However, the two basins differ from recent models in having a pseudo-symmetric morphology. Here, we address the Early Cretaceous tectono-sedimentary evolution of the Arzacq and Tartas rift basins and the lithospheric processes associated with their genesis. These basins did not suffer major brittle deformation during rifting stage, but nevertheless record a major change in their configuration between the Aptian and the Albian. The Arzacq Basin shifted from a symmetric to a slightly asymmetric configuration. This change was controlled by gravity sliding of the pre-rift sedimentary cover in the eastern Arzacq Basin moving its depocenter south, and by salt diapirism in the western Arzacq Basin moving its depocenter north. Several inherited Paleozoic structures were reactivated as transfer zones and appear to be responsible for this depocenter shift, the emplacement of salt diapirs, at same time regionally limiting gravity sliding. The Tartas Basin maintained a symmetric regime throughout the Early Cretaceous, except along the Barlanès transfer zone where the Lussagnet salt diapir originated. Two drivers of subsidence are thus envisaged in the Arzacq Basin: a Neocomian-Aptian crustal thinning stage, followed by reactivation of Paleozoic faults in Albian time accompanied by salt diapirism and gravity cover sliding. The Mauléon North Pyrenean Basin and its north adjacent Tartas and Arzacq basins thus formed part of a series of rift basins that progressed in maturity southward, from a simple sag basin (Tartas) to a slightly asymmetric basin (aborted detachment, Arzacq) to a hyperthinned basin (Mauléon). Our results offer new insights on the role of: (1) structural inheritance in partitioning extensional strain, (2) transfer zones as able to influence the sedimentary record of basins during crustal thinning, and (3) pre-rift salt décollements as able to separate the structural styles of sub- and supra-salt successions. • Pseudo-symmetric rift basins resulting from Early Cretaceous hyperextension. • Barremian-Aptian sag basins, decoupled deformation between upper and lower crust. • Albian-Cenomanian asymmetric rifting stage. • Synrift salt tectonic and basinward cover gliding along Jurassic salt décollement. • Role of inherited transverse transfer zones during rift formation.

Tectono-sedimentary evolution and petroleum systems of the Mundaú subbasin: A new deep-water exploration frontier in equatorial Brazil

The Brazilian equatorial margin (BEM) evolved in response to transform motion between Brazil and Africa. In 2012, Petrobras drilled the Pecem well in the Mundau subbasin (Ceara Basin) of the BEM to record the first deep-water oil discovery in the region. This work investigates the deep-water evolution of the Mundau subbasin focusing on its structural and sedimentary evolution, and characterizes the petroleum systems in this new exploration frontier. For such purposes, poststack seismic reflection, borehole, and geochemical data were used. Three tectono-stratigraphic sequences representing synrift (Mundau Formation), transitional (Paracuru Formation), and drift strata (Ubarana Formation) were divided into seven seismic units. Different tectonic domains were interpreted: proximal, distal, and Romanche Fracture Zone. Typical structures of transform margins, such as marginal ridges and marginal plateaus, were not identified in the Mundau subbasin. Instead, the subbasin was predominantly deformed by transtensional movements. The Mundau and Paracuru Formations are mature within the oil window, whereas the Ubarana Formation is immature. Main reservoir intervals consist of approximately 1-m (∼3.28-ft)-thick intercalations of sandstone between shales, siltstones, and marls. The seal rocks comprise shales in the Ubarana Formation, whereas the hydrocarbon trap is related to an unconformity and a normal fault. This work concludes that the Paracuru Formation is the main source and reservoir in the deep-water Mundau subbasin, effectively comprising a Paracuru–Paracuru petroleum system. The results have significant implications for petroleum exploration in the BEM by proposing a developed transitional petroleum system in the distal parts of northeastern Brazil.

LA "GONFOLITE LOMBARDA": STRATIGRAFIA E SIGNIFICATO NELL'EVOLUZIONE DEL MARGINE SUDALPINO

The Oligocene-Miocene succession of the "Gonfolite Lombarda" outcrops in Western Lombardy and is largely represented in the subsurface of the northern PO Plain. In the this group was considered as a typical example of post- orogenic molasse deposit. The new data suggest that it represents a clastic wedge infilling a deep foreland basin flanking a zone of continental collision. The stratigraphic evolution of the succession strictly reflects the tectono-sedimentary evolution of the basin.
 The succession (almost 3000 m thick) between Como and Varese covers a time span from late early Oligocene (late Rupelian) at least to early Miocene (Burdigalian). It consists of clastic sediments deposited in a deep-sea environment. Both the benthic Foraminifera and the macrofossil assemblages indicate that these sediments were deposited in the epibathial zone (from 500-700 m to 1000-1300 m) throughout all the time span considered. The succession can be splitted in two main segments based on their different sedimentary characters and because they are separated by a regional unconformity corresponding to a hiatus of several million years. The lower one is represented by the Chiasso Formation (about 170m thick) and the upper one by the Gonfolite Group s. Str. (about 2800 m thick).
 The Chiasso Formation is a depositional sequence late Oligocene (late Rupelian to early Chattian) in age. It consists of mudstones and rare thin-bedded turbidites, representing slope or slope-base deposits. The overlying Gonfolite Group represents the build-up of several deep sea fan systems one on top of the other during the very late Oligocene (late Chattian) to the early Miocene (Aquitanian- Burdigalian) and perhaps to the middle Miocene. Resedimented conglomerates infilled deeply incised canyons confined by natural levees in their distal part. The canyons evolved laterally and distally to still partly confined sandy depositional lobes during the early Miocene.
 In the Gonfolite Group three depositional sequences could be recognized. The first one is represented by the Como Conglomerate (800-1500 m thick) and of some heteropic formations, covering a time span from late Chattian to early Burdigalian. This depositional sequence represents an asymmetric megacycle with an initillly very rapid progradation of the conglomeratic system followed by its gradual regression and, in the Como area, by a westward shift of the system axis. Moreover, it is worth mentioning that pebbles of granodiorite-diorite called "ghiandone and serizzo" of the Val Masin0-Val Bregaglia Massif make their appearance already in the basal part of the Como Conglomerate.
 The second depositional sequence consists of the Lucino Conglomerate (800-1000 m thick) and of some heteropic formations. It represents a gradual progradation of the whole deep sea fan system during the late earIy Miocene (Burdigalian).
 In the Varese area, the Gurone Sandstone (120 m thick) may represent a third depositional sequence, which because of its stratigraphic position is younger than the late Burdigalian, and it appears to be deposited prior to the late Miocene (Tortonian).
 The "Gonfolite Lombarda" basin was interested by an intense and continue tectonic activity with at least two periods of "crisis" occurring in the late Chattian and in the early Burdigalian. Because of the strong tectonic Control it's difficult to correlate the "Gonfolite Lombarda" depositional sequences with the generalized sea level curves.

Garnet trace element geochemistry as a sediment provenance indicator: An example from the Qaidam basin, northern Tibet

Abstract Major element geochemistry of detrital garnet is a widely-used approach for sedimentary provenance analysis, in particular for unravelling parent-rock lithology of siliciclastic sediments. However, garnets from felsic crystalline rocks (e.g., intermediate–acidic igneous rocks and metapelites) often have similar major element composition. This results in ambiguity of provenance interpretation in most cases. Here, we collect trace element data of garnets from different rock types to explore the feasibility of detrital garnet trace element geochemistry in sediment provenance analysis. The Qaidam basin in northern Tibet is taken as an example and provenance of Cenozoic sedimentary rocks therein is interpreted based on detrital garnet trace element composition. We find that garnets in intermediate–acidic igneous rocks have much higher heavy rare earth element (ΣHREE > 600 ppm) and yttrium (Y > 800 ppm) abundances than garnets in metapelites (ΣHREE 4 ppm) and zinc (Zn > 150 ppm) abundances than garnets in low-, medium-grade metapelites (up to amphibolite facies). Based on these findings, we suggest that Fe- and Mn-rich detrital garnets in the Cenozoic sedimentary rocks from the northern Qaidam basin were probably derived from low-, medium-grade metapelites and Mg-rich, Ca-poor detrital garnets therein were most likely derived from granulite-facies metapelites. This provenance interpretation supports that the Qilian Mountains to the north was the major source for the northern Qaidam basin and major deformation style along the Altyn Tagh Fault to west have been dominated by large-amplitude lateral offset and extrusion, rather than crustal thickening and uplift during the early Cenozoic. This study emphasizes high potential of detrital garnet trace element geochemistry in provenance analysis and reconstruction of tectono-sedimentary evolution of clastic sedimentary basins.

Tectono-sedimentary characteristics in the area with distributed normal faults: Lower Cretaceous Prosopis Formation in the northern slope of Bongor Basin, Chad

Based on an integrated database (e.g., core observations, well logs, and seismic data), the characteristics of depositional systems, as well as the response to tectonics, are systemically delineated in the Prosopis Formation of the Lower Cretaceous at Bongor Basin, Chad. The tectonic setting of this study area experienced multiple, active sub-basins with narrow-spaced intra-basinal normal faults. The multiple normal faults formed in the initial rifted stage leading to the development of a corridor-shaped basin consisting of small-scale sub-basins. As this basin is attracting increased attention due to further hydrocarbon exploration, deciphering the process of sediment partition, especially in the initial rifted stage, would provide a further understanding of the tectono-sedimentary evolution in lacustrine rift basins. Based on core observations, well logs, and three-dimensional seismic data, fan-delta and sub-lacustrine-fan depositional systems are widely developed in this area. Two depositional systems (e.g., fan-delta and sub-lacustrine-fan) and three categories of slope break belts (single-faulted, step-faulted, and flexure types) have been identified. Overall, during the initial rifted stage, the formation of multiple normal faults mainly dominates the geomorphology and sediment supplies that generate the spatio-temporal features of depositional systems in semi-closed lacustrine basins. Climatic perturbations, furthermore, regulated the composition of sediments (coarse versus fine deposits). For the economic perspective, this study highlights the significance of fault systems in further hydrocarbon exploration during the initial rifted stage of lacustrine basins.

The Variscan foreland in Poland revisited: new data and new concepts

An earlier concept of the Variscan foreland in Poland (Narkiewicz, 2007) is reconsidered in the light of new stratigraphic, tectonic and geophysical evidence, providing new data on Devonian sedimentation, Carboniferous magmatism and the deep crustal structure of SE Poland. Regional comparisons with the tectonic evolution of Central Europe and the Black Sea region show that the subsidence pattern in the foreland was controlled by alternating phases of accelerated convergence and tectonic standstill along the southern margin of Euramerica. In particular, the Bretonian (Devonian/Carboniferous) compressional deformation resulted from intensified orogenic convergence in the West-Central uropean Variscides leading to closure of the Saxo-Thuringian Basin and East-Sudetic back-arc basin. Another turning point in the regional tectonosedimentary development around the Mississippian–Pennsylvanian boundary was probably related to the termination of terrane collision in the Black Sea region. Late Pennsylvanian basin inversion was associated with a roughly N–S tectonic shortening. This was partly due to displacement along pre-existing basement discontinuities comprising reactivated Caledonian sutures that also pre-determined the Devonian–Carboniferous basin boundaries. Consequently, deeply-rooted tectonic zones, including the Krakow-Lubliniec and Holy Cross faults and the Teisseyre-Tornquist Zone, focussed maximum compressional and transpressional deformation and associated uplift. Such a concept of terminal Variscan tectonism, termed here the “decoupled model”, is discussed with reference to the recently proposed “coupled model”. The latter assumes a wide extent of the Variscan Orogen, reaching as far as the marginal Radom–Kraśnik Fold-and-Thrust Belt linked with the Bohemian Massif through a major basal detachment. It is concluded that the “decoupled model” is more consistent with the documented seismic and structural evidence as well as with the present knowledge of the heterogeneous pre-Devonian basement in southern Poland.

A Cretaceous carbonate escarpment from Western Sicily (Italy): biostratigraphy and tectono-sedimentary evolution

The presence of a huge carbonate slope of Cretaceous age is recorded in some imbricated thrust sheets from the Maghrebian fold-and-thrust belt cropping out in northwesternmost Sicily (southern Italy). The sedimentological features of this escarpment, named as the Western Sicily Cretaceous Escarpment (WSCE), have been recently described. The present paper aims to provide a detailed bio-chronostratigraphic characterization of the different facies types that occur in the four lithostratigraphic units spanning the whole slope depositional system. The detailed biostratigraphic analysis and correlation of a number of well-exposed sections allowed to differentiate eight informal biozones and to place the different studied sections, either from a single tectonic unit or from different ones, in a reliable chronostratigraphic frame. The integration of sedimentological and biostratigraphic data allowed in turn to time-constrain the main tectono-sedimentary events along the WSCE. In particular: i) the abrupt transformation from a carbonate ramp to a tectonically-controlled escarpment during the Berriasian-Valanginian; ii) the peak of tectonic instability leading to the emplacement of thick megabreccia bodies and repeated submarine volcanic emissions during the Aptian- Cenomanian; iii) the almost coeval increase in the skeletal supply in response to highstand shedding occurred during the Albian-Cenomanian; iv) the tectonic backstepping of the carbonate depositional system during the Senonian ending with the definitive shutdown of the carbonate factory in the late Maastrichtian. The acquired biostratigraphic dataset is in large part new for the Cretaceous of Sicily and provides information on the associations that populated a southwestern Tethyan carbonate platform during the Cretaceous.

Polygenetic mélanges: a glimpse on tectonic, sedimentary and diapiric recycling in convergent margins

A significant part of melanges recognized in exhumed convergent margins around the world has been recently documented to have chiefly originated from masse transport and subsurface remobilization and disruption (i.e. melanges, from sedimentary and mud–serpentinite diapiric processes and from in situ fluidification–disruption). Tectonic and/or sedimentary processes occurring during subsequent multiple deformational events of convergent margin evolution commonly overprint and significantly rework the primary (sedimentary or diapiric) melange fabric, forming polygenetic melanges. This ultimately complicates their distinction from true tectonic melanges, masking part of the recorded tectono-sedimentary evolution of the associated convergent margin. The contributions gathered in this thematic collection explore with different approaches (from field structural and stratigraphic observations to geophysical analyses) different types of polygenetic melange, at various scales, around the world. These studies conclude that the understanding of this type of melange may provide crucial insights for a more detailed interpretation of the evolution of ancient and modern convergent margins, and of processes and mechanisms triggering potential natural hazards (earthquakes and tsunamis). Case studies include the Apennines in the Central Mediterranean region, the Carpathians in Central Europe and the Nankai Prism in Japan. Thematic collection: This article is part of the ‘Polygenetic melanges: a glimpse on tectonic sedimentary and diapiric recycling in convergent margins’ collection available at https://www.lyellcollection.org/cc/polygenetic-melanges

Mesozoic tectono-sedimentary evolution of the Trapanese SouthernTethyan margin (NW Sicily) integrating facies and stratigraphic analysis with subsidence history

Several Mesozoic successions of the Southern Tethyan margin were accumulated on a carbonate platform evolving to pelagic plateau depositional systems. Rifting paleotectonics was the main process conditioning their tectono-sedimentary evolution. The well-exposed outcrops in the NW Sicilian fold and thrust belt of the so-called Trapanese carbonate platform to pelagic succession highlight the occurrence of lateral facies and thickness changes, paleofaults, volcanics, and resedimented deposits. The integration of facies analysis, stratigraphic data, and subsidence history have permitted to decipher the polyphase tectono-sedimentary evolution and to distinguish different depositional settings. Structural lows, filled with up to 100m of pillow lavas and reworked deposits, appear as intraplatform basins bordered by structural highs, as horst ridges, characterised by condensed sedimentation, and isolated seamounts. These sectors were linked among them by stepped fault margins, scalloped margins and depositional slopes. The tectonic history, highlighted by the backstripped sections, reveals superimposed evolutionary stages reflecting rifting and rapid tectonic subsidence, leading to continental break-up (Late Triassic-Early Jurassic stage); the Middle Jurassic stage reflects slow thermal subsidence in the basin shoulders and higher rates in the intervening depressions; the Late Jurassic-Early Cretaceous regional uplift interrupts the thermal subsidence curve trend. The tract of the Late Cretaceous-Eocene curve suggests again slow thermal post-rift subsidence, also influenced by sediment load. The different subsidence curves, reconstructed from different positions in the sedimentary basin, demonstrate that its evolution could be driven by the identified syn-sedimentary faults that were formed and/or re-activated during several tectonic events encompassing the whole Jurassic-Cretaceous time period. The regional significance of this tectonics indicates that the Sicilian sector of the Southern Tethyan continental margin was tectonically active for the whole Mesozoic.The reconstructed paleophysiography of the Trapanese continental margin, during the Mesozoic, appears characterised by a segmented and drowned carbonate platform with morphostructural highs separated by deep channels. The comparison with the present-day morphostructural setting of some regions of the Atlantic continental margins (e.g. Caribbean, Brazilian equatorial margin), suggests also for the study region that the occurrence of transcurrent/transform faults and stretching of the continental lithosphere can have played an important role in determining the physiographic conformation.

Late Cenozoic tectono-sedimentary evolution of the Ulukışla Basin: progressive basin development in south-central Turkey

The Ulukisla Basin is one of the most important late Cretaceous-Cenozoic basins in central Anatolia. The basin is surrounded by the Bolkar Mountains of Tauride Platform in the south, the Nigde Massif of Central Anatolian Crystalline Complex to the north, and the Ecemis Fault Zone and Aladag Mountains in the east. The fact that time interval proposed for the formation of Ulukisla Basin is quite wide and more than one tectonic regime prevailed in the region, have led to various suggestions concerning the evolution of the basin. While the suggestions majorly examine the character of the basin during the late Cretaceous-early Cenozoic, the number of detailed studies on the status of the basin in the late Cenozoic is limited. In this study, we focused on the less-studied late Cenozoic evolution to differentiate the tectonic phases that controlled the development of Ulukisla Basin through structural data, and elaborate the responses of sedimentation and paleogeography during this period through detailed facies analyses. Our findings indicate that the Ulukisla Basin, which started to develop as a supradetachment basin in the late Cretaceous, has continued its extensional development progressively during its Cenozoic history. While the relatively well-studied early Cenozoic sequences represent a marine environment that was rapidly changed shallow- to deep-sea environment and then gained a shallow character by the middle Eocene, sedimentary features and fossil contents of the late Cenozoic units characterize deposition started in a paralic environment changing into a terrestrial environment rapidly, as a result of isolation by the uplifting of surrounding topographies while the basin continues its development under an extensional tectonic regime. However, the extensional basin history surceased in post-middle Eocene and post-middle Miocene, probably caused by the closing processes of the different branches of Neotethys Ocean.

Tectono-sedimentary signature of the second rift phase in multiphase rifts: A case study in the Lufeng Depression (38–33.9 Ma), Pearl River Mouth Basin, south China sea

Compared to first rift phase (RP1) or single rift basins, the relationship between fault behaviours and depositional architecture during the second rift phase (RP2) remains insufficiently understood in multiphase rifts. This study attempts to provide implications for tectono-sedimentary signatures during the RP2 in multiphase rift evolution, according to an integrated analysis of 3D seismic reflections, wire logs and cores from the Lufeng Depression in the Pearl River Mouth Basin, South China Sea. The four recognised third-order sequences, ESQ1-4, define a two-stage tectono-sedimentary evolution, including an early (ESQ1-2) and a late stage (ESQ3-4) of the RP2 (38–33.8 Ma) in the Lufeng Depression. Fan-deltaic, braided deltaic sandstone-prone and lacustrine mud-prone deposits are interpreted from the basin margin towards to the central areas. During the early stage of the RP2, two relatively steep dipping E-W striking faults in the northern area were very active, undergoing rapid reactivation with a high displacement, while other faults were less active, had low displacements with respect to the extension direction and possibly represent pre-existing fault geometries. Two tectono-depositional signatures are identified during the early stage of the RP2: 1) facilitation of newly captured axially-dominated deltaic systems in the rapidly reactivated fault propagated areas, as a more uniform distribution of connected and elongated depocentres establishes an axial-supply drainage catchment; 2) sustained previous drainages from the end of the RP1 showed an increase of dip-slope sourced systems in low-displacement faulted-controlled areas, i.e. these areas lack fault-controlled topographic re-organisation but show establishment of a hanging dip-slope. The late stage of the RP2 is characterised by a low-accommodation basin as faulting activities totally waned, and thus large-sized shallow-water deltaic systems and long-distance transported sandstones are promoted. This study highlights the distinctive stratigraphic architectures and associated sediment dispersal patterns induced by progressive fault activity during the RP2 cycle. Furthermore, the proposed depositional signatures may be used as a reference when studying less data-rich multiphase rifts elsewhere.

Tectonic evolution of Tianshan-Bogda-Kelameili mountains, clastic wedge basin infill and chronostratigraphic divisions in the source-to-sink systems of Permian-Jurassic, southern Junggar Basin

Continuous Paleozoic-Mesozoic sediment records within Junggar Basin, Northwestern China, provide details on tectonic evolution of the surrounding Tianshan, Bogda, and Kelameili orogenic belts. We compiled 5250 zircon U-Pb ages from 58 samples (602 new and 4648 published ages) and integrated with published paleo-current directions, paleo-geography, and well core data to reconstruct the uplift timing and provenance for source-to-sink systems of southern Junggar Basin from Permian to Jurassic. This reconstruction strongly suggests that the Kelameili area, middle Southern Tianshan, and western Northern Tianshan had been uplifted before the Permian. However, the uplift of southern Central Tianshan, eastern Bogda, and western Bogda initiated in middle Permian, late Permian, and early Jurassic, respectively. In addition, maximum depositional age calculated from youngest zircon U-Pb ages modes provides new constrains on the chronostratigraphy of southern Junggar Basin, including the Jingjingzigou Fm., Karamay Fm., Haojiagou Fm., Shirenzigou Fm., Lucaogou Fm., Toutunhe Fm., and Qigu Fm. This study provides a basis for a larger reconstruction of the stratigraphic and tectono-sedimentary evolution in response to the tectonic interactions between southern Junggar Basin and surrounding ranges during Permian through Jurassic times.

Tectono-sedimentary evolution of the Mesoproterozoic basins in the southern Yan-Liao and Mianchi-Queshan areas: insights from stratigraphic pattern and detrital zircon geochronology

The widespread Mesoproterozoic successions around the world have recorded the breakup of the ancient supercontinent Columbia. In the North China Craton (NCC), the Mesoproterozoic basins in the Yan-Liao and southern NCC are the important evidence to study the nature and evolution of the Mesoproterozoic basins. In this study, we scrutinized the stratigraphic pattern and detrital zircon U–Pb geochronology in the southern Yan-Liao and Mianchi-Queshan areas in the southern NCC, to investigate the evolutionary relationship between the Mesoproterozoic basins in the north and south of NCC. Detrital zircons from the Mesoproterozoic sequence in the southern Yan-Liao areas showed monotonous source with age peak at ca. 2500 Ma, corresponding well with the ages of the Neoarchean complex in the central NCC. However, the Mesoproterozoic sequence in the Mianchi-Queshan areas, which is represented by the Ruyang Group, exhibited significantly different characteristics with influx of much younger zircons. The southern Yan-Liao and Mianchi-Queshan areas showed distinct similarity in the stratigraphic pattern, reflected by the Mesoproterozoic successions in these two areas being both bracketed by two sequence boundaries and further divided into two sequences under a uniform sea-level change. The Mesoproterozoic strata in these two areas probably possessed a correlative relationship in the stratigraphic patterns and basin evolutionary history.

Tectono-sedimentary evolution of a fossil ocean-continent transition: Tasna nappe, central Alps (SE Switzerland)

AbstractMagma-poor ocean-continent transitions at distal rifted margins record complex stratigraphic interactions engendered by extreme crustal thinning and mantle exhumation. The Tasna ocean-continent transition, exposed in the Middle Penninic Tasna nappe in eastern Switzerland, is so far the only known example where the lateral transition from continental crust to exhumed serpentinized mantle lithosphere is exposed and not overprinted by later Alpine deformation. This paper presents sedimentological, structural, and petrographical observations and detrital zircon provenance data to document: (1) the processes controlling continental hyperextension and mantle exhumation; and (2) the facies, depositional systems, sediment sources, delivery pathways, and depositional stacking patterns associated with magma-poor ocean-continent transitions. Our results show that the basement units of the Tasna ocean-continent transition are composed of prerift upper and lower crust and subcontinental mantle rocks juxtaposed as part of the continental crustal thinning process. The absence of pervasive, synrift deformation in the lower-crustal rocks indicates that the thinning was likely achieved by deformation along localized shear zones before being exhumed at the seafloor by brittle, late extensional detachment faulting and not by any form of lower-crustal flow.The age of the first sediments deposited on the continental crust and exhumed mantle, the so-called Tonschiefer Formation, is considered to be Late Jurassic. A key observation is that the restored morpho-tectonic and sedimentary evolution of the Tasna ocean-continent transition shows the intercalation of downdip, transported platform-derived sediments and along-axis–derived siliciclastic sediments originating from the recycling of prerift sediments, local basement, and/or extra-Alpine sources.

Similar Oligo-Miocene tectono-sedimentary evolution of the Paratethyan branches represented by the Moldavidian Basin and Maghrebian Flysch Basin

A comparison of the stratigraphic record between two different branches of the Tethys is attempted for the first time. This study concerns the main Oligocene-Miocene tectono-sedimentary events in the Cenozoic units of the Moldavidian Basin (Romanian Eastern Carpathians) and the Maghrebian Flysch Basin (Maghrebian Chain and its lateral extension in the Betic and Southern Apennine Chains). Both basins are characterized by three main general Oligo-Miocene successions (internal, mixed, and external) corresponding to three subdomains controlled by the geological evolution of opposite plate (or microplate) margins and affected by a similar tectonic evolution. The successions of the three subdomains of the two basins show very similar features regarding stratigraphic records (lithofacies and petrofacies associations, unconformities, marker-levels, age), and the space-time sediment supply diversification (i.e., immature and super-mature arenites coming from opposite margins). Furthermore, pre-, syn- and post-orogenic successions have been identified in the geological reconstructions of both basins. The tectonic control on depositional processes (i.e., a large amount of siliciclastic supply confined in restricted time ranges, widespread volcaniclastites linked to acid-intermediate penecontemporaneous volcanic activity), and the appearance of indicators of syn-sedimentary tectonic activity (turbidites, slumps, and olistostromes) result in correlable events related to deformation phases that in turn are indicative of a similar evolution. Also, the basinal evolutionary stages (i.e., beginning of terrigenous supply, thrust-top basin formation and gravitational sliding, molassic and/or intramontane sedimentary cycles), the timing of deformation phases (drifting, foredeep), and geotectonic events (from extension to compression and post-orogenic deformation) seem to be similar. All results are encompassed in an evolutionary geodynamic model considered in the context of the Africa-Europe convergence where intermediate microplates are involved. This complex framework implies a progressive reorientation of convergence direction of these microplates that occurs during similar geodynamic events leading to the closure of the western Tethys Ocean and its related late-Alpine branches. This comparative approach, if applied to similar evolutionary phases of other mountain chains, can be useful for different geological contexts of other orogenic belts, especially to check the major general geological constraints for their evolution.