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We present a detailed description of the Middle Miocene (Chokrakian and Karaganian) depositional environments of the Eastern Paratethys Sea in the southern Caspian Basin. The Chokrakian comprises a 500-m-thick succession of marls and sandstones, termed herein Javarem Formation, which formed in coastal marine environments. The lower Javarem Fm. Developed in calm lagoonal settings, indicating frequent exposure under a predominantly dry climate and occasional formation of evaporites. The upper part of the Javarem Fm. Is characterized by mixed siliciclastic-carbonatic sediments with ooids of agitated, warm, hypersaline tidal shoals. Above follows the about 500-m-thick Vashi Formation, which is correlated with the Karaganian regional stage. The formation is characterized by an alternation of reddish marls with thick sandstones and gravel beds with terrestrial gastropods, ubiquitous pedogenetic features and occasional root horizons. The depositional environment is interpreted as a floodplain with gravelly channels of an arid to semiarid climate. The successions of the Javarem and Vashi formations capture the transition from the shallow marine Iranian shelf into the northern Iranian coastal plain around 13.8 Ma, following the onset of the Miocene Climate Transition and the coinciding global sea level drop around the Langhian/Serravallian boundary. [ABSTRACT FROM AUTHOR]

One of the most remarkable features of the central Northern Calcareous Alps (Eastern Alps, Austria) is the widespread presence of Upper Triassic deep-water carbonates (the Hallstatt facies) and Permo-Triassic evaporites resting on deep-water Middle Jurassic strata and their underlying Upper Triassic shallow-water carbonate platform successions. The Hallstatt facies and accompanying evaporites have been classically interpreted to originate either from a location south of the time-equivalent carbonate platforms, or to have been deposited in deeper water seaways within the broad platform domain. To date, this dispute has been addressed mostly through the analysis of Triassic and Jurassic facies distribution in map view, which, however, is subject to some degree of ambiguity and subjectivity. In this contribution we present, for the first time, sequentially restored regional cross-sections through the central Northern Calcareous Alps to understand the implications of the contrasting paleogeographic models. We present (a) an interpretation based on a highly allochthonous origin of the Triassic deep-water units and (b) an interpretation based on their relative autochthony in which we incorporate the potential influence of salt tectonics in the central NCA. The restored cross-sections provide a framework within which the alternative scenarios and their paleogeographic implications can be better understood. Through this analysis we propose that salt tectonics in the central NCA can provide a valid explanation for apparent inconsistencies in the relative autochthony scenario and thus constitutes a reasonable alternative to the currently accepted allochthony scenario. [ABSTRACT FROM AUTHOR]

On the southwestern margin of the North Patagonian Massif (Argentina), there is a NW–SE trending belt consisting of igneous and metamorphic rocks that is named the Central Patagonian Igneous Metamorphic Belt. It defines the boundary between the mentioned massif and southern Patagonia (including the Deseado Massif). It is debatable whether this belt belongs to an orogen generated by accretion or collision and whether it was created in a single event or over the course of several events. Paleogeographic reconstructions were conducted to answer this query, confirming that there are tectonic processes involved in two events: the Chanic (Devonian) and the Gondwanan (late Carboniferous–early Permian) events. They show a movement of South America toward the SW during which an accretionary orogen was built during the Chanic event between ca. 400 Ma and ca. 360 Ma. Later, the paleogeographic reconstructions show an abrupt change in the movement of South America; it is proposed that due to this movement, the previously built orogen collapsed between ca. 360 Ma and ca. 330 Ma. During the Gondwanan event, the subduction surrounding Pangea in the Patagonian belt caused plutonic emplacement in the already-existing orogen structures and paleogeographic reconstructions depict South America with a movement toward the northeast, which involves a displacement due to a slab pull from the northern Paleotethys Ocean boundary. It is further supported that lateral displacement between Gondwana domains brought forth by this slab pull is what led to the assembly between the North Patagonian Massif and southern Patagonia. [ABSTRACT FROM AUTHOR]

The mid-Cretaceous Langshan Formation, which crops out on the north Lhasa subterrane, central Tibet, is composed of a thick carbonate sequence with local volcanic rock and sandstone interlayers. In this study, we present data from the Asuo area, including fossil assemblages within carbonates, detrital zircon U–Pb ages of sandstone interlayers, zircon U–Pb ages and whole-rock geochemistry of andesite interlayers within the Langshan Formation to provide new constraints on the tectonic evolution of north Lhasa subterrane. The fossil assemblage indicates that the Langshan Formation was deposited on a carbonate platform at water depths of approximately 0–50 m during the late Albian to early Cenomanian period. The volcanic rock interlayers (111–109 Ma) primarily consist of high-K calc-alkaline andesites/dacites (SiO2: 56.48–67.03 wt. %; Mg#: 42.5–58.9). These andesites exhibit limited evidence of significant modification by crustal contamination. The high Mg# values and arc-like trace element signatures suggest that the andesites may have resulted from partial melting of the mantle wedge induced by fluids derived from a subducted slab. Furthermore, the lithic fragments within the sandstone interlayers predominantly exhibit characteristics of "recycled orogen" and "arc orogen," indicating that the sandstone was derived from recycled ancient strata and a few magmatic arc materials. Considering the regional paleogeographic context, the carbonate accumulation of the Langshan Formation appears to have occurred nearly simultaneously with a period of high-flux magmatism, long-term slow tectonic subsidence, and the closure of the Meso-Tethys Ocean. The arc–arc "soft" collision provides a plausible mechanism to explain the widespread and rapid accumulation of thick carbonates in collision settings. It also accounts for the presence of magmatic rocks with enhanced mantle contributions on both sides of the north Lhasa subterrane. [ABSTRACT FROM AUTHOR]

Resolving the Mesozoic and Cenozoic palaeogeography and geomorphologic development of outcropping Variscan basement is a pre-condition for the understanding of central European geodynamics. For our study, we have applied apatite fission-track (AFT) and apatite (U–Th)/He (AHe) thermochronology to surface rocks of the southeastern Bohemian Massif. 46 samples were examined by the AFT method. Additional AHe dating was applied to 8 of them. The AFT ages range from 251 ± 46 to 60.2 ± 4.8 Ma. AHe ages range from 25 to 525 Ma with rather high intra-sample scatter. On a regional scale, the AFT ages generally decrease from mainly late Variscan in the NE to Late Cretaceous and Paleocene in the SW. This regional age asymmetry relative to the NW–SE trending watershed of the Weinsberg Forest is neither compatible with regional uplift of a single block nor with large-scale lithospheric updoming. The lack of age breaks along late Variscan faults demonstrates that strong vertical offset cannot have occurred in Cretaceous and Cenozoic times. Inverse modeling of thermochronological data indicates regional Early Cretaceous cooling and subsequent reheating during the Late Cretaceous. Rocks of the present-day surface were heated up to a temperature of ca. 80 °C without full reset of the AFT system. This thermal history is compatible with the existence of a large mainland in Early Cretaceous times and a subsequent sedimentary reburial until the Campanian on the order of up to 1 km overburden. Parts of the exhumed weathering basal relief to the N and NE of the Weinsberg Forest are inherited as 'sealed relief' from Middle Cretaceous time. The observed regional asymmetry of AFT data is best explained by the development of a continental escarpment adjacent to the North Penninic Ocean in latest Cretaceous to Paleogene times. A final episode of accelerated cooling after ca. 20 Ma, as indicated by thermochronological modeling, is tentatively ascribed to either collisional coupling of the Alpine-Carpathian nappe pile with its northern foreland or to East-Alpine slab detachment. [ABSTRACT FROM AUTHOR]

We report detrital zircon ages from the Upper Cretaceous (Campanian–Maastrichtian) turbiditic sandstones from the Pontides and the Anatolide–Tauride Block, which were located on opposite margins of the Tethys ocean during most of the Paleozoic and Mesozoic. The large data set includes both published and new detrital zircon ages from the Upper Cretaceous Pontide sandstones (2730 zircon ages from 26 samples) and new detrital zircon ages from the uppermost Cretaceous Bornova Flysch of the Anatolide–Tauride Block (378 ages from five samples). Phanerozoic detrital zircons from the Upper Cretaceous sandstones of the Pontides are predominantly Late Cretaceous (56%) followed by Carboniferous (7.9%), Devonian (5.3%), Jurassic (3.1%) and Triassic (2.9%). In contrast, there are no Cretaceous and Jurassic detrital zircons in the uppermost Cretaceous Bornova Flysch, and the Phanerozoic detrital zircon populations are mainly Carboniferous (41.3%), Triassic (7.1%), Permian (6.9%) and Devonian (5.3%). The absence of Cretaceous and Jurassic zircons in the Bornova Flysch shows that there was no sediment transport between the Pontides and the Anatolide–Tauride Block during the latest Cretaceous (75–70 Ma); it also shows that the latest Cretaceous – Paleocene deformation of the Bornova Flysch Zone predates the collision between the Pontides and the Anatolide–Tauride Block, and is associated with ophiolite obduction. The dominance of Carboniferous detrital zircons in the Bornova Flysch Zone underlines that Carboniferous magmatic activity in the Anatolide–Tauride Block, and hence on the northern margin of Gondwana, was more significant than hitherto recognized. [ABSTRACT FROM AUTHOR]

Accretionary complexes and their hosted Ocean Plate Stratigraphy (OPS) units record a full story of ancient oceans from their birth at mid-oceanic ridges to their death at subduction zones. However, their reconstruction is difficult because accretionary complexes possess very complicated structures and therefore require careful and detailed in-field geological and structural studies and up-to-date analytical data. In this paper, we present results of detailed geological and structural studies of OPS sediments and new U–Pb detrital zircon data from sandstones of the Gorki Formation, a major part of the Ulaanbaatar accretionary prism/complex. The structure of the Gorki Fm. consists of five units separated from each other by parallel NE-striking regional faults and deformed by intra-formational detachments. It formed by offscraping and accretion of OPS sediments and subsequent thrusting and duplexing. Each unit is characterized by a specific association of OPS rocks, type and degree of deformation, style of folding and bedding geometry suggesting dychronous deposition and accretion of marine sediments. The ages and lithologies of the five units of the Gorki Fm. allowed us to trace the whole story of OPS sedimentation and further deformation—from oceanic floor (pre-accretion), to young and growing accretionary prism (syn-accretion) to accretionary prism stabilization (post-accretion). The dominantly southward vergence of the Gorki OPS thrust sheets suggests a generally northward subduction polarity. The greywacke sandstones of Unit I yielded U–Pb zircon ages ranging from 389 to 317 Ma with two main peaks at 346 and 367 Ma suggesting a provenance dominated by Famennian to Visean igneous complexes. The absence of the Famennian peak in the U–Pb detrital zircon spectra of sandstones from younger Unit II suggests tectonic erosion of a late Devonian arc. In general, the repeated layer-parallel thrusts inside lithologically uniform sediment beds indicate a regime of strong compression along the Benioff plane during subduction at a Pacific-type convergent plate boundary. [ABSTRACT FROM AUTHOR]

Some recent models challenge the position and extension of the assumed oceanic basins formed through the break-up of Rodinia, and the tectonic processes involved in the Gondwana assembly, making the investigation of the Early Neoproterozoic record of great relevance. Within the South-American Atlantic margin, the Punta del Este Terrane (PET) of the Dom Feliciano Belt (DFB) comprises a unique Tonian to Ediacaran record, and has a strategic position to reconstruct spatio-temporal relationships with the southern African orogenic belts. Novel zircon U–Pb and Lu–Hf data from the PET basement orthogneisses display Tonian magmatic ages (805–760 Ma) and Hf isotopic signatures indicative of mainly crustal/metasedimentary sources, (Nd TDM ages: 2.2–1.9 Ga, and εHf(t): − 12 to − 4). The basement paragneisses yielded late Paleoproterozoic to Neoproterozoic U–Pb ages, but dominantly positive εHf(t) values. The presented results confirm the correlation of the PET with the Coastal Terrane of the Kaoko Belt, and discard the idea of the Nico Pérez Terrane as a source. Detrital zircon U–Pb and Lu–Hf data from the Rocha Formation yielded a main peak at ca. 660 Ma, with the Neoproterozoic grains showing a εHf(t) between + 1 and + 14. The deposition age of the Rocha Formation is constrained by the youngest detrital zircon age peak (660 Ma), and the beginning of the deposition of the Sierra de Aguirre Formation (580 Ma). The data indicate common sources with the Marmora Terrane, and it is thus proposed that the Rocha Formation belongs to the Gariep Belt, and it was juxtaposed during the Ediacaran to the DFB. [ABSTRACT FROM AUTHOR]

New paleocurrent directions of the gravity flow sediments were measured in the Slovak part of the Biele Karpaty Mts. Paleocurrent directions were sorted and grouped according to lithostratigraphic units and lithotypes. The sedimentation area of the Biele Karpaty Unit was located in the westernmost part of the Magura Basin. Paleocurrent analysis proves the direct connection between the former sedimentary area of the Biele Karpaty Unit with the Magura Basin and the Rhenodanubian Basin during the Late Cretaceous to middle Eocene. The transport of the distal turbidites was parallel to the southern edge of the basin in the Ondrášovec Mb (Campanian). One lateral proximal source of debris flows of the Drietomica Mb (Maastrichtian), several lateral sources of debris flows of the Chabová Mb (Danian), several lateral sources from SE and one massive source of turbidites of the Javorina Mb (Campanian—Maastrichtian) and one massive source of the Svodnice Fm (Danian—Ypresian) turbidites supplied quartz–carbonate material in to the basin from NE. The occurrence of glauconite Sst and Magura type Sst proves the connection with the rest of the Magura Basin at the end of the sedimentation of the Svodnice Fm (Danian—Ypresian), when the paleocurrent directions tend from NE from Bystrica Mb in the eastern part of the region and were fed from the Fore-Magura Ridge and Southern Magura Ridge. The paleocurrents directed also from NW from Greifenstein Fm of the Rhenodanubian Flysch in the western part of the region. The sea floor relief in the studied area was mostly flat until the Campanian. Since the Maastrichtian, the relatively flat sea floor has been segmented into shallow paleo-valleys and elevations, which was manifested in significant thickness fluctuations of accumulated deposits. [ABSTRACT FROM AUTHOR]

The Oligocene–early Miocene Tranquitas Formation in the southern Chaco foreland basin records the onset of Central Andean shortening. The aims of this contribution are to: (1) provide original data of the depositional conditions of the Tranquitas Formation, (2) to determine the role of tectonic and climate influence on the depositional conditions and on the composition of these deposits and (3) propose an evolutionary model of accumulation based on a sequence stratigraphic approach. The detailed analysis of these deposits resulted in the definition of six facies associations, including: complex sandy narrow sheets (FA1), sandy narrow sheets with lateral accretion surfaces (FA2), sandstone ribbons (FA3), tabular muddy-sandstone deposits (FA4), sandstone lobes (FA5), and fine-grained deposits (FA6). Based on the spatial distribution and the vertical stacking of these associations, the Tranquitas Formation was divided into two major intervals. Interval 1 (lower section) is characterized by braided fluvial deposits and represents low accommodation conditions with a high proportion of channel deposits. Interval 2 (upper section) tends to an increase in the accommodation space characterized by the better preservation of floodplain deposits in moderate to high sinuosity meandering fluvial systems. The integration of paleocurrent, petrography, and clay mineralogy analyses indicates that detrital components come from the orogenic region located to the west, in an overfilled stage of the foreland basin. Clay mineral assemblage analysis suggests a long-term climate change from drier to more humid conditions and reflects the climate effect on the depositional paleoenvironments developed in the distal position of the basin. In addition, the resultant vertical and lateral stacking of sedimentary sequences representing different paleoenvironments of the Tranquitas Formation could be correlated with the Oligocene–early Miocene Petaca and lower-Yecua formations located in the center and north of the Chaco foreland basin. [ABSTRACT FROM AUTHOR]

The late Carboniferous–early Permian represents a key period in the Phanerozoic history, given the major global geodynamic and climate modifications. The aim of this work is to better understand the context and characteristics of the sedimentation recorded in the continental environments of eastern equatorial Pangea at this time, through the example of the Autun Basin (northeastern Massif Central, France). The Autun Basin contains the historical stratotype of the Autunian continental stage, and its stratigraphy was recently improved by accurate numerical ages. This basin formed in an extensional tectonic context during the latest stages of the Variscan orogeny, and it is essential to study its paleoenvironmental evolution to provide new insights into the sedimentary evolution of contemporaneous surrounding basins. Using field and subsurface data, we propose a refined sedimentological model for the Autun Basin, relying on updated facies interpretations, organic matter content fluctuations, and sequence stratigraphy concepts and correlations. The continental environments of the lower sedimentary succession of the Autun Basin, previously considered to be fluvial and lacustrine, are herein re-interpreted as mainly lacustrine, comprising fine-grained organic matter-rich deposits, and supplied by coarser-grained deltaic siliciclastic sediments, without preservation of strict fluvial sedimentation. The determination of the sequence stratigraphy cycles, strengthened by the quantification of the organic matter content, and reflected by the temporal succession of progradational and retrogradational trends, is used to determine new correlations between several sections, as well as to reconstruct the paleoenvironment evolution at the Carboniferous–Permian transition. This study provides evidence that the sedimentation area of the Autun Basin at the time of its filling was much larger than the preserved basin area, and suggests connections with contemporaneous neighboring French basins, pointing to a large sedimentary system in the northeastern Massif Central area rather than narrow and isolated basins. [ABSTRACT FROM AUTHOR]

Metabasic rocks of the ophiolitic sequences of the Glockner Nappe and Eclogite Zone in the south-central Tauern Window, Austria, reveal important insights into rifting and spreading of the Alpine Tethys. U–Pb dating of magmatic zircons yields a concordant 157 ± 2 Ma crystallization age for the precursor of a coarse-grained metagabbro from the Glockner Nappe. The Late Jurassic intrusion age is coeval with mafic plutonic activity in the Western and Central Alps. Although Penninic ophiolitic sequences in tectonic windows of the Eastern Alps are usually disrupted, an ocean–continent transition setting can be reconstructed for the Glockner Nappe, similar to many ophiolites in the Liguria–Piemont domain in the Western and Central Alps. Together, these observations strongly suggest a formation in the Liguria–Piemont branch of the Alpine Tethys and are inconsistent with a formation in the Valais domain. This finding has important implications for paleogeographic reconstructions of the Penninic realm in the Eastern Alps. Whereas the Glockner Nappe metagabbro and metabasalts clearly reveal their depleted mantle origin, the metabasic rocks of the Eclogite Zone record a more complex formation history involving depleted mantle melting and crustal assimilation in a continental margin setting. [ABSTRACT FROM AUTHOR]

In shallow-water limestones of the Plassen Formation in the Tirolic nappe of the Northern Calcareous Alps, bauxite was formed on karstified and tilted platform margin grainstones to boundstones around the ?Kimmeridgian/Tithonian boundary, or in the Early Tithonian as proven by Protopeneroplis striata Weynschenk, Labyrinthina mirabilis Weynschenk, and Salpingoporella pygmaea Gümbel. The platform established on top of the obducted ophiolite nappe stack. The onset of unroofing at the Kimmeridgian/Tithonian boundary exposed ophiolites to weathering, forming laterites, and bauxites. The weathered ophiolitic material was shed on the tilted, emerged, and karstified platform, where the bauxite accumulated. Continued subsidence led to flooding, and a Tithonian transgressive carbonate sequence sealed the bauxites. XRD analysis of the bauxite yields a composition of mainly boehmite with hematite and some berthierine, kaolinite, and chromite. SEM analysis verified magnetite, hematite, rutile, chromite, zircon, ferropseudobrookite, ilmenite, monazite, xenotime, and garnet distributed in pisoids and within the matrix. The pisoids reach a millimeter in size and partly show cores of older, larger pisoids. The composition of the chromites indicates an ophiolitic origin. Geochemical examination using major- and trace elements points to a mafic andesitic to basaltic parent material contaminated with highly fractionated rocks from an island arc. Formation of Early Tithonian bauxites in shallow-water limestones confirms Middle to Early Late Jurassic ophiolite obduction. This was followed by uplift and unroofing of the orogen from the Kimmeridgian/Tithonian boundary onwards after a period of relative tectonic quiescence with an onset of carbonate platforms during the Kimmeridgian on top of the nappe stack and the obducted Neo-Tethys ophiolites. [ABSTRACT FROM AUTHOR]

The eastern Anti-Atlas of Morocco represents one of the most completely exposed and perfectly documented biostratigraphic records of the entire Devonian worldwide. Paleogeographically it is clearly differentiated into shallow basins, pelagic platforms, and land areas which are newly defined and illustrated, one from the top of the Middle Devonian, the other from the middle Famennian as two of the most characteristic intervals. The dominant paleogeographic feature is the T-shaped Tafilalt Platform which, in spite of common unconformities and hiatuses, provides the best-documented biostratigraphic record through the entire Devonian. The westernmost termination of this platform was emerged during most of the Devonian (and locally even earlier) and became only flooded again by the Tournaisian transgression. In contrast to previous interpretations, this area is considered as autochthonous. In the Mader Basin subsidence was up to one hundred times higher with respect to the adjacent platforms, but water depth during the Middle Devonian to middle Famennian interval generally remained above storm-wave base. Devonian rocks are only patchily and incompletely preserved on the Mader Platform, which can be considered as an intermittently flooded peninsula connected to the Lower Paleozoic farther west. The major paleotectonic element of the entire area is the Great Anti-Atlas Fault, a sinistral strike-slip fault, which sharply confines the above-mentioned realms in the south. [ABSTRACT FROM AUTHOR]

Understanding the sediment distribution and basin context of the different Oligo–Miocene successions in the eastern Maghrebides thrust belt of northern Tunisia is challenging and several contrasting models have been proposed. We present the results of detailed field mapping together with facies, microfacies and microfaunal analyses of the NE Mogod Mountains that allowed refining the Bizerte geologic map and reconstructing the Oligocene–early Miocene depositional environment of northern Tunisia. Facies characterization of the Jebel Sebaâ, Cap-Blanc and Bizerte Town sections demonstrate their deposition by submarine gravity flows typical of the Numidian Flysch Formation, rather than the Fortuna Formation as previously proposed. This is supported by the occurrence of deep marine microfossils. The association of deepwater massive sandstone facies and a high proportion of shale-clast conglomerates in the Jebel Zoukar, Ras El Korane and Jebel Sebaâ sections are interpreted as bypass channel facies, representing proximal deposition. The section at La Baie des Carrières is distinguished by its high glauconite content, a rich microfauna of larger benthic foraminifera, Ditrupa and echinoids is typical of a shallow marine depositional environment and interpreted as part of the Grès de Bejaoua Formation. The Oligocene sections at Beni Aouf and Nefza also show Grès de Bejaoua affinities, but with some deepening of the marine environment represented by pelagic foraminifera-rich mudstones, and calcareous glauconitic sandstones. The facies distribution, depositional environments and the sediment routing of these time equivalent deposits appears to be dictated by topographic highs and inherited faults (e.g. salt dome paleohigh, El Hairech-Ichkeul ridge, Zaghouan Thrust fault and faults affecting the basin-floor). Within this framework, the northern part of the salt dome area acted as topographic high that guided the fluvial drainage pattern of the Fortuna Formation along a SW-NE trend. The absence of early Miocene deposits in the Tellian domain indicates that this area has been part of a forebulge setting since the late Oligocene. Corresponding foredeep subsidence led to submergence of the Bizerte-Nefza area and deposition of the deep marine Numidian Flysch Formation. The advance of the fold-and-thrust belt since the late Burdigalian–Langhian induced the vertical stacking of foredeep deposits over the forebulge succession. [ABSTRACT FROM AUTHOR]

The Cadomian basement in central and southern Europe is composed by Ediacaran–Early Cambrian sequences that appear dismembered along the Variscan Orogen. These ancient series contain geochemical and isotopic keys related to their deposition in different basins located along the paleo margin of Gondwana. The southwest of Iberian Massif (Ossa–Morena Complex) contains an excellent representation of Cadomian basement. The oldest sedimentary succession of this region, the Serie Negra Group (c. 600–541 Ma), is composed by the Montemolín Formation which consists of metapelites, metagreywackes and abundant amphibolites; and the Tentudía Formation which consists of metagreywackes, black quartzites and metapelites. The whole-rock and Nd isotopic geochemistry of the Montemolín and Tentudía formations, are consistent with a deposition in a back-arc or fore-arc setting. Their Nd isotopic composition shows highly negative εNd(t) values in a range between − 6.9 and − 11.5, resulting in old Paleoproterozoic Nd model ages between 1.9 and 1.7 Ga. The Nd isotopic signatures obtained for the Cadomian basement in the Iberian Massif are almost identical to those obtained for equivalent sedimentary series in the Saxo-Thuringian Zone (Bohemian Massif), where Nd model ages range between 2 and 1.6 Ga. The limited variability of these Nd-TDM ages suggests that the southwestern Iberian and North Bohemian series shared a common source during Ediacaran times, which would be located close to the periphery of the West African Craton. The Nd isotopic data considered herein provide solid evidence about the peri-Gondwanan location and correlation between the Cadomian basement of southwestern Iberia and North Bohemia. [ABSTRACT FROM AUTHOR]

The vertebrate fossil-bearing upper Eocene strata in the Fayum area, Egypt exhibit complex lateral facies variations making their stratigraphy and depositional setting a matter of debate. They are exceptionally well exposed in the Kom Aushim Quarry region, NE Fayum, where they have hitherto been rarely studied. A recent study in a nearby locality had imposed a tide-dominated delta for these strata. The present study provides insight into this sedimentary succession and introduces an updated sedimentological interpretation of the Umm Rigl Member; basal Qasr El-Sagha Formation relying on outcrop facies analysis and sequence stratigraphic data. Eight short stratigraphic sections were measured and fully described in terms of lithology, grain size, stratal boundaries and sedimentary structures. The mud-dominated lower unit of the Umm Rigl Member consists of four vertically stacked shallowing/coarsening upward bay-margin/lagoonal deltas. The strata in the upper unit of the Umm Rigl Member are interpreted as incised valley back infilled with fluvial, upper estuary, tidal flat passing upwards into shallow and open marine deposits. The strata represent two incomplete depositional sequences, separated by a sequence boundary defined by an abrupt basin-ward shift of facies and equates with the base of incised valley previously recognized in Wadi Al-Hitan area. This boundary may equate with the early Priabonian Pr-2 global sea-level fall. Based on transgressive stacking of facies, the strata of the upper unit are interpreted as estuarine rather than deltaic system. This updated interpretation enhances understanding of depositional history and the paleogeographic evolution of NE Fayum during the late Eocene. [ABSTRACT FROM AUTHOR]

The SW Iberian margin is an oblique passive margin developed during the Mesozoic, as part of the opening of the westernmost Ligurian Tethys. The Algarve Basin developed on the SW Iberian margin and its sedimentary record was strongly controlled by tectonics. The Algarve Basin was dominated during the Mesozoic by WSW–ENE trending extensional faults and their associated depocenters, segmented by oblique NW–SE transfer zones. Two major NW–SE trending transfer zones connected the Algarve Basin to the Gorringe Bank in the west and to the Betic Basin in the east. The SW Iberian margin was later inverted during Late Cretaceous to Cenozoic times, due to convergence between Africa and Iberia. Inversion of the Algarve Basin and the SW Iberian margin was controlled by both the WSW–ENE and NW–SE trending structures formed during the passive margin phase. The evolution of the Algarve Basin during the Mesozoic and up to the Paleogene is documented in this paper through paleogeographic reconstructions based on field geology and reinterpretation of offshore seismic and well data. [ABSTRACT FROM AUTHOR]

In the supercontinent of Rodinia, Baltica occurred next to Amazonia, then the two drifted away when Rodinia broke up. By the end of the Neoproterozoic, Baltica became an independent continent. At that time, Timanide orogen developed at its modern northeastern margin. In most paleogeographical reconstructions, the opposite (SW, Tornquist) edge faced the Tornquist Ocean and remained just a passive margin till the arrival of the Gondwana-born East Avalonia in the late Ordovician. However, preliminary isotopic studies of detrital zircons from the Tornquist passive margin succession hinted that rock components of Gondwana derivation reached Baltica already in the early Cambrian. In this paper, we examine 18 drill-cores of Ediacaran-Cambrian and Ordovician siliciclastic rocks from the tectonostratigraphic units along the SW–NE transect from Upper Silesia (USB) via Małopolska (MB) and the Holy Cross Mts (HCM) to the East European Platform (EEP), SE Poland, in terms of the provenance data gained from the LA-ICP-MS and SHRIMP analyses of 32 zircon samples. Rocks from all the units revealed abundant Cadomian 0.7–0.55 Ga detrital zircons (15–50% of the total analyzed grains) and other grains that yielded peaks at 0.9–1.2, 1.4–1.6, 1.8–2.2, 2.7–3.0 Ga assignable to Baltica rather than Amazonia. Such age spectra in the USB, HCM and EEP prove the proximity of peripheral (peri-Gondwanan) fragments of the Cadomian orogen to Baltica. These fragments formed the Teissyere-Tornquist Terrane Assemblage (TTA) that obliquely docked and overrode the thinned southwestern edge of Baltica which earlier accumulated Neoproterozoic rift and passive margin deposits. Our data show that in the late Ediacaran-early Cambrian, parts of the Cadomian orogenic belt became accreted to Baltica. [ABSTRACT FROM AUTHOR]

The NW Iberian Allochthon and the Teplá-Barrandian and Moldanubian zones represent the internal parts of the Variscan belt in their respective domains. A correlation based on the lithological association, protolith ages, metamorphic evolution, detrital zircon age spectra and tectonic setting is attempted between the NW Iberian Massif and SE Bohemian Massif in order to check whether they could have formed part of the same allochthonous stack. The Galicia-Trás-os-Montes Zone of the Iberian Massif and the internal zones of the Bohemian Massif include from bottom to top a Parautochthon and Lower Allochthon representing the outer edge of the northern Gondwana margin, an oceanic Middle Allochthon with Cambro-Ordovician and Early Devonian ophiolites and an Upper Allochthon interpreted as a peri-Gondwanan terrane. Early Variscan, subduction-related high-pressure metamorphism characterizes many of the allochthonous units, with ages younging from the structurally upper to the lower units from 400–385 Ma to 370–360 Ma, respectively. High- and ultrahigh-pressure metamorphism occurred also in the Saxothuringian Autochthon at 360–340 Ma, but not in the NW Iberian Autochthon. The different behavior of the Autochthon in the Iberian and Bohemian massifs accounts for their distinct evolutions from 360 Ma onward. We conclude that the Upper Allochthon was a unique peri-Gondwanan terrane, whereas the Middle Allochthon represents units of the same peri-Gondwanan ocean, opened at the Cambro-Ordovician boundary, and having recorded localized renewed activity in the Silurian–Early Devonian. No other oceans separated the Lower Allochthon, Parautochthon and Autochthon. [ABSTRACT FROM AUTHOR]

The Variscan orogeny occurred as a result of the Late Devonian to Late Carboniferous collision and accretion of Gondwana-derived microcontinents and continental masses with those of Laurussia. The irregular boundaries of the colliding continents caused isochronous transpressional and transtensional tectonics, accompanied by a complex pattern of intracontinental shear zones at the scale of the southern European Variscides. These shear zones and their configuration controlled the subsequent evolution of Permian to Middle Triassic paleogeography. The geographic distribution, from Morocco to the Eastern Alps, of the Late Carboniferous–Permian up to Triassic basins, most of which are considered as pull-apart basins, was related with the development of the Late Palaeozoic intracontinental shear network. Our analysis of the stratigraphic, tectonic and volcanic features of the Late Carboniferous/Permian continental basins across the Laurussia/Gondwana boundary reveals the role of the East Variscan Shear Zone during this time as a precursory lineament for the development of the Permian to Triassic rifting of Pangaea and the following opening of oceanic basins (e.g., the Neothetyan Ocean). [ABSTRACT FROM AUTHOR]

The Ulukışla 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 Niğde Massif of Central Anatolian Crystalline Complex to the north, and the Ecemiş Fault Zone and Aladağ Mountains in the east. The fact that time interval proposed for the formation of Ulukışla 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 Ulukışla Basin through structural data, and elaborate the responses of sedimentation and paleogeography during this period through detailed facies analyses. Our findings indicate that the Ulukışla 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. [ABSTRACT FROM AUTHOR]

The Plattenkalk Unit forms the structurally deepest nappe of the External Hellenides and plays a key role for the reconstruction of Triassic paleogeography in the western Tethyan realm. To shed light on the provenance of the Plattenkalk Unit, we present microfabrics and U–Pb detrital zircon data obtained from quartzite and metaconglomerate of its basal part (Kastania and Transitional Beds exposed on the southern Peloponnesus). A Minoan-type age spectrum of detrital zircons, together with inherited deformation microfabrics of detrital components, points to a very low- to low-grade metamorphic basement as source rock that was situated along the northern passive margin of Apulia facing the Neotethys in the north. The siliciclastic rocks of the Kastania Beds reflect the late Permian/early Triassic opening of the Neotethys, whereas the Transitional Beds indicate the late Triassic facies change toward the Pantokrator-type dolomite, which is a characteristic rock of late Triassic Tethyan carbonate platforms. Dolomite and evaporites of the Trypali Unit, on the other hand, were deposited vis-à-vis along the southern passive margin of Cimmeria. This Triassic configuration of Tethyan basins fits well with the S/SW-directed transport and the recent vertical succession of the Hellenic nappes. The proposed Triassic position of the Plattenkalk basin implies that the Apulian microplate was not part of the Cimmerian block since Permian times. The separation of the Apulian microplate from Gondwana is attributed to the Jurassic breakup of Pangea resulting in the opening of the Mesogean ocean, the relics of which are undergoing subduction beneath the Aegean microplate still today. [ABSTRACT FROM AUTHOR]

The mid-Langhian ("Badenian") flooding fully reconnected the semi-isolated Central Paratethys realm with the Mediterranean and, thereby, drastically changed the middle Miocene paleogeography of Central Europe. Due to the scattered stratigraphic record and scarcity of independent age constraints in some areas, the precise age and underlying mechanism are still debated. We present integrated chronostratigraphic data from five sections in the eastern part of the system to reconstruct the flooding event distal from the strait to the Mediterranean. By applying modern Mediterranean biochronology (planktonic foraminifera and calcareous nannofossils), supplemented by an 40Ar/39Ar age on a tuff, we demonstrate that the widespread open marine settings in the NW Transylvanian Basin were definitely installed after 14.9 Ma (MMi4d biozone), and in most areas before 14.4 Ma. In the marginal study area in the SE Carpathian Foredeep, fully marine conditions likely set in slightly later (14.6–14.4 Ma). There, short-lived marine incursions into the brackish environment occurred since the latest Burdigalian ("pre-flooding phase"). The new ages overlap with the flooding in the majority of the Central Paratethys (~ 14.9–14.4 Ma), and with marine overflow into the Black Sea (14.85 Ma). We suggest that the transgression was driven by subsidence of the Pannonian Basin, by creating accommodation space and diminishing barriers between sub-basins, but was likely enhanced by a global sea-level rise. Finally, we speculate that the scarcity of all calcareous material in the SE Carpathian Foredeep before the mid-Langhian flooding might be related to pulses of nutrient-rich brackish and low pH water from the neighboring Black Sea Basin. [ABSTRACT FROM AUTHOR]

Late Paleogene syn-tectonic magmatic products are known from sandstones contained in the North Alpine (NAFB) and South Alpine (SAFB) foreland basins and in the South Alpine pelagic Trento Basin. The generally turbiditic and mass-flow deposits grade up from marly hemipelagic deeper water series. The source and amount of the reworked volcanic materials have been in debate for a long time. As a proxy for the magma-derived input we use the U–Pb geochronology and geochemistry [176Hf/177Hf(t) and Eu/Eu* ratios] of detrital zircons, and evaluate their temporal and genetic relationships with potential volcanic sources in the Periadriatic magmatic systems (Adamello, Bergell, Biella). The oldest volcanic sources (Lutetian–Priabonian) we identify are in the Trento Basin and Glarus NAFB. During most Rupelian, Bergell and Biella volcaniclastics were delivered to the NAFB in the Glarus, Alpe de Taveyanne and Haute-Savoie. Bergell and minor Adamello magmatic material were supplied to the Villa Olmo Conglomerate in the SAFB. During late Rupelian–Chattian in the entire NAFB, the influx of Paleogene volcanic material faded out. At the same time in the SAFB, the Como Conglomerate shows mixed input from Biella and Bergell. High numbers of old zircons (> 90%) in the NAFB document the asymmetry of the early Alpine orogenic wedge exposing large basement areas to the north of the Periadriatic intrusions. The syn-sedimentary right-lateral movement along the Periadriatic fault system is identified as the main driver of magmatic activity, uplift, and exposure to erosion and transport to the basins. On this base, the dynamics of the early Alpine drainage systems are reconstructed with new accuracy. [ABSTRACT FROM AUTHOR]

A comprehensive understanding of the relationship between the Sino-Korean Craton (SKC) and the Gondwana supercontinent is crucial for accurate reconstruction of the tectonic evolution and early Paleozoic paleogeography of East Asia. To explore the link between the SKC and peri-Gondwana, we provide new detrital zircon U–Pb age data from litho- and bio-stratigraphically constrained lower Cambrian to Lower Ordovician sandstone deposits from the eastern margin of the SKC (Taebaeksan Basin). Results indicate that the two distinct age spectra of detrital zircon resulted from provenance change combined with a strong function of sediment grain size within host siliciclastic rocks of the Taebaek Group. The age spectra from coarse-grained sandstones display Paleoproterozoic (1.9 Ga) and Neoarchean (~ 2.5 Ga) peaks, indicating that the sediments were supplied from the basement rocks of the SKC. Conversely, age spectra from fine-grained siliciclastics contain late Mesoproterozoic (~ 1.0 Ga) and Neoproterozoic (~ 0.6 Ga) peaks, with or without a Paleoproterozoic signal, consistent with a Gondwanan sediment origin. These different age populations have been documented in multiple Cambrian and Ordovician sequences of the SKC and are consistently well correlated with sediment grain size. Coarse-grained sediments, sourced primarily from local basement rocks, were deposited in coastal, nearshore, and shelf environments, whereas fine-grained sediments were derived from more distal sources (i.e., the Gondwana mainland and/or the Gyeonggi Marginal Belt) and deposited in inner to outer shelf settings. Therefore, the repeated occurrence of sediment with two distinct provenances in the Cambrian–Ordovician siliciclastics of the SKC is likely a result of provenance shift integrated with changing depositional environments in an epeiric platform. This yielded variations in sediment grain size and source rock provenance, with and/or without a tectonic activity. Consequently, our results indicate that the SKC was adjacent to Gondwana during the early Paleozoic. [ABSTRACT FROM AUTHOR]

The nature of the warm climates of the Cretaceous has been enigmatic since the first numerical climate models were run in the late 1970s. Quantitative simulations of the paleoclimate have consistently failed to agree with information from plant and animal fossils and climate sensitive sediments. The 'cold continental interior paradox' (first described by DeConto et al. in Barrera E, Johnson C (eds) Evolution of the Cretaceous Ocean/climate system, vol 332. Geological Society of America Special Paper, Boulder, pp 391–406, 1999), has been an enigma, with extensive continental interiors, especially in northeast Asia, modeled as below freezing in spite of plant and other evidence to the contrary. We reconsider the paleoelevations of specific areas, particularly along the northeastern Siberian continental margin, where paleofloras indeed indicate higher temperatures than suggested by current climate models. Evidence for significant masses of ice on land during even the otherwise warmest times of the Cretaceous is solved by reinterpretation of the δ18O record of fossil plankton. The signal interpreted as an increase in ice volume on land is the same as the signal for an increase in the volume of groundwater reservoirs on land. The problem of a warm Arctic, where fossil floras indicate that they never experienced freezing conditions in winter, could not be solved by numerical simulations using higher CO2 equivalent greenhouse gas concentrations. We propose a solution by assuming that paleoelevations were less than today and that there were much more extensive wetlands (lakes, meandering rivers, swamps, bogs) on the continents than previously assumed. Using ~ 8 × CO2 equivalent greenhouse gas concentrations and assuming 50–75% water surfaces providing water vapor as a supplementary greenhouse gas on the continents reduces the meridional temperature gradients. Under these conditions the equatorial to polar region temperature gradients produce conditions compatible with fossil and sedimentological evidence. [ABSTRACT FROM AUTHOR]

The Helanshan Tectonic Belt and its environs within the northwestern Ordos Terrane, western North China Craton, have been envisaged as aulacogen or plate boundary separating the Alxa Massif from the Ordos Block during Cambrian. However, it conflicts with geological and geophysical facts. This study presents integrated stratigraphic, sedimentary and geochronological data from the Cambrian strata in the northwestern Ordos Terrane to constrain the Cambrian tectonic evolutionary process of the western North China Craton. The Cambrian successions comprise, in ascending order, evaporite platform facies, restricted-open platform facies and evaporite platform facies, featuring a vertical transgression–regression sequence. An eastward-shoaling paleogeography was documented, evidenced by shallow-water dolomite layers enriched in the east and the detritus derived from northeast. Ages of detrital zircons span from 2566 to 1649 Ma with predominant two peaks around 2500 and 1850 Ma, suggesting these Cambrian detritus were sourced from the Archean–Paleoproterozoic rocks in the Yimeng highland. Comparable fossil associations and unified paleogeography system supported that there was no Cambrian plate boundary in the northwestern Ordos Terrane, implying the Alxa Massif was part of the North China Craton during the Cambrian. The westward-deepening facies differentiation with low-angle topography contradicts with the tectonic model of "Helan aulacogen". In combination with the relatively low subsidence rate and rare magmatic–metamorphic activities, we argue that the Cambrian shallow marine system in the western North China Craton was the continent-ward extension of passive continental margin basin system related to the spreading of the Paleo-Asian Ocean. [ABSTRACT FROM AUTHOR]

Eight samples from Oligocene sedimentary rocks of the Marseille-Aubagne basins have been analysed for their detrital zircon age spectra. These age spectra provide information about the regional evolution, from Oligocene to Archaean times. The Carboniferous Variscan and the Late Cretaceous to Eocene Pyreneo-Provençal belts represent the latest main tectonic, magmatic, and volcanic events that formed the major zircon age populations found in studied sediments. The obtained detrital zircon age record of the Marseille-Aubagne basins comprises eleven detrital zircon age clusters. They reflect the long and complex geologic history of the sediments source areas and can be ascribed to the opening of the western Mediterranean, the Variscan, Cadomian and Pan-African belts, to an unknown Mesoproterozoic event, to the Eburnean orogeny of West Africa and to the different tectono-metamorphic events that took place in Archaean times. In general, the Palaeo- and Mesozoic events are ascribed to the dispersal of Western and Eastern Gondwana and the Pangaean supercontinent cycle. Thus, the successive recycling of zircon grains from older and the incorporation of them to younger belts lead to new geodynamical models for the northern Gondwana margin evolution. Significant amounts of Mesoproterozoic detrital zircon are at odds with previous hypotheses and re-open the question of the provenance of these zircon age populations. Therefore, this tiny tertiary basin is a natural archive which records the main geological events in SE France and its vicinity. [ABSTRACT FROM AUTHOR]

U/Pb zircon dating and trace element geochemical analysis were performed on rhyolite clasts of different Middle Jurassic sedimentary mélanges from the Western Carpathian and Dinaric orogen. These igneous clast-bearing sedimentary successions were deposited on the westernmost passive margin of the Neotethys Ocean. During the latest Jurassic and Cretaceous, they became parts of different nappe stacks forming now the Inner Western Carpathians and some inselbergs within the Pannonian Basin. The Meliata nappe was stacked on the northern passive margin, while the Telekesoldal and Mónosbél nappes were part of the imbricated western-southwestern margin. U/Pb dating of the 100 m-sized rhyolite blocks and redeposited smaller clasts within the mélange, and fine-grained sediments formed two age groups: 222.6 ± 6.7 and 209.0 ± 9 Ma. Trace element geochemistry suggested within-plate continental volcanism as magma source. However, the measured ages are definitely younger than the classic, rift-related Anisian-Ladinian (238-242 Ma) magmatism, which was wide-spread along the western and southwestern margin of the Neotethys Ocean (e.g., Dolomites and different Dinaridic units). On the other hand, similarly, Late Triassic ages are reported from tuff intercalations from the Outer Dinarides and Western Carpathians, along with even more sparse effusive rocks of the Slovenian Trough. Trace element (incl. rare-earth element) analysis showed positive correlation between the mélange clasts and the in situ Late Triassic rhyolites of the Slovenian Trough. This newly established link between the mélange nappes in NE Hungary and the in situ Late Triassic rhyolites in the Slovenian Trough make a good opportunity to reconsider both Middle Jurassic paleogeography, and later tectonic deformations, which led to the separation of the source area and the redeposited clasts. [ABSTRACT FROM AUTHOR]

Combined sedimentological and structural analysis was carried out in the field and on 2D seismic reflection profiles to recognize pre-orogenic structures in a Cretaceous fold-and-thrust belt. Detailed field observations were made in the Keszthely Hills, Western Hungary, while 2D seismic interpretation was carried out in the neighbouring Zala Basin. As a result, a fault-controlled intraplatform basin system was identified by a detailed analysis of bounding faults, and related outcrop-scale structures. The Norian-Rhaetian (227-201.3 Ma) synsedimentary faulting was associated with talus breccia formation, small-scale faulting, and dyke formation, in addition to slumping and other soft-sediment deformations. Based on the distribution of talus breccia, WNW-ESE-trending map-scale normal faults were identified in the Keszthely Hills, which is in agreement with the directly observed outcrop-scale synsedimentary faults. On seismic sections, similar WNW- or NW-trending Late Triassic normal faults were identified based on thickness variations of the syn-rift sediments and the presence of wedge-shaped bodies of talus breccia. Normal faulting occurred already in the Norian, and extensional tectonics was active through the Early and Middle Jurassic. The Late Triassic grabens of the western Transdanubian Range could be correlated with those in western part of the Southern Alps, and the Bajuvaric nappe system of the Northern Calcareous Alps. These grabens were situated on the proximal Adriatic margin, and they represent the first sign of the Alpine Tethys rifting. The locus of extension was laterally migrated westward, towards the distal Adriatic margin during Early and Middle Jurassic. [ABSTRACT FROM AUTHOR]

The island of Corsica, which belongs to the southern Variscan realm, was detached from southern France in the Tertiary. Alongside Alpine and Variscan edifices, it carries outliers of Neoproterozoic metasediments and Lower Paleozoic siliciclastics including Ordovician sandstone and conglomerates as well as Hirnantian diamictites in its NW sector. We investigated the U-Pb-Hf of detrital zircons of basement metasediments and overlying Ordovician sandstone and channeling conglomerate to constrain their provenance, the timing of their deposition, and to deduce the late Ediacaran to Ordovician paleogeography. The youngest detrital zircons in the metasediments are 0.55-0.53 Ga indicating their maximum age of deposition is Late Ediacaran to Early Cambrian, thus classifying the Corsica basement metasediments as Cadomian. The U-Pb analyses revealed that a preponderance of the detrital zircons in the basement micaschist and quartzite portray Neoproterozoic ages concentrating between 0.55 and 0.65 Ga. This is partly consistent with derivation from Pan-African terranes of north Africa yet the presence of detrital zircons younger than ~ 0.6 Ga indicates significant input from Cadomian magmatic arcs that resided within or at the margin of the Cadomian basin in which the metasediments of Corsica were deposited. εHf values of the Ediacaran zircons varies between samples, indicating the provenance comprised both, juvenile arcs and magmatic arcs that involved various degrees of mixing with old crustal components. The Hf-TDM ages of many of the Ediacaran-aged zircons point to a plausible involvement of Meso-Paleoproterozoic crust in the generation of these Cadomian arcs. The presence of small but fairly distinguished populations of Mesoproterozoic-aged (1.0-1.6 Ga) as well as 2.0-2.2 Ga and 2.4-2.6 Ga detrital zircons in the Cadomian metasediments farther indicates the presence of such crust in the provenance. Although Mesoproterozoic detrital zircons are usually considered the hallmark of Avalonian terranes, the presence of Hirnantian glacial sediments at the Corsican sequence indicates it resided in the vicinity of Gondwana. We therefore postulate that the Pre-Neoproterozoic zircons have sourced from exotic crustal vestiges that were entrained and accreted within the Cadomian realm itself. The transition into the overlying Ordovician sandstone and conglomerate marks a major change in the provenance, possibly pointing to lateral motions along the strike of the peripheral Cadomian domain. The youngest concordant detrital zircon in the Ordovician (“Ciuttone”) sandstone yielded an age of 0.48 Ga. The detrital zircon ages define an overwhelming concentration at 0.55 Ga, indicating the source of the Ordovician sandstone was cut off from the Gondwana hinterland and that sand was exclusively derived from a latest Ediacaran arc. In view of the sharp detrital zircon age peak, the Corsica Ordovician sandstone cannot be straightforwardly correlated with Armorican sandstone because the detrital zircon spectra of the latter are generally broader, indicating derivation from various sectors of the North Gondwana crust. εHf(t) values of the 0.55 Ga zircons are mostly positive and the corresponding TDM ages at 0.7-1.2 Ga indicating derivation from a juvenile island arc. While TDM ages of this type are common for late Ediacaran Avalonian rocks, the presence of Hirnantian diamictite in Corsica further substantiates that the aforementioned 0.55 Ga island arc evolved in the peripheral Cadomian realm. As a whole, the U-Pb-Hf zircon data from the Corsica sequences reveal the presence of juvenile Cadomian arcs alongside Cadomian arcs that recycled ancient (pre-Neoproterozoic) crust. Along strike variations of this type are known from the Japanese islands, in line with the peripheral Cadomian orogeny being an ancient analog of a Western-Pacific type plate boundary. [ABSTRACT FROM AUTHOR]

The Paleocene Shashi Formation, the host formation of potassium-rich brines and solid potash in the Jianghan Basin, central China, is characterized by rift sediments in a composite basin-mountain system. However, the provenance of the Paleocene Jianghan Basin remains poorly understood. A combined study of petrographic examination, geochemical analysis, and zircon U-Pb dating was conducted to characterize the provenance of the Shashi Formation. The petrographic analysis of the Shashi Formation reveals that these samples have predominantly quartz-lithic compositions with minor contributions from other minerals. Whole-rock geochemical data indicate that this formation experienced only slight to moderate alteration. The chondrite-normalized rare earth element (REE) patterns of these samples are essentially parallel to those of the upper continental crust (UCC), as their negative Eu-anomalies and Th/Sc and La/Th ratios suggest an average source composition similar to that of the UCC. These values, together with plots of their Th/U vs. Th ratios, suggest that certain samples have undergone moderate degrees of weathering and sedimentary recycling. The analysis of major and trace elements (i.e., La/Th-Hf, Th/Sc-Zr/Sc, La/Y-Zr/Sc, TiO2-Fe2O3T + MgO, Al2O3/SiO2-Fe2O3T + MgO) indicates that their sedimentary sources were felsic rocks from an active continental margin or a continental arc containing a minor amount of recycled sediments derived from a passive continental margin. The Shashi Formation contains detrital zircons that primarily have U-Pb ages of 2.5, 1.8 Ga, 725-965, 425-475, 310-350 and 200-260 Ma. These results reveal that the pre-Ordovician zircons are derived from recycled sediments of the Yangtze Block and thus originate from the surrounding ranges. The magmatic rocks of the South Qinling Belt and the Jiangnan Orogen are responsible for supplying the Ordovician to Triassic detrital zircons. These provenance data combined with paleocurrent analyses can be used to identify multiple source characteristics in the Jianghan Basin. During the Early Paleocene, most clastic material was derived from a southern source; during the Late Paleocene, northern and western sources contributed most of the detritus to the basin. The supply of clastic material was thus broadly variable and widely dispersed throughout the basin. This study shows that the architecture of the region and the rifting process exerted important influences on this sediment dispersal. [ABSTRACT FROM AUTHOR]

The Western Sierras Pampeanas (WSP) of Argentina record a protracted geological history from the Mesoproterozoic assembly of the Rodinia supercontinent to the early Paleozoic tectonic evolution of SW Gondwana. Two well-known orogenies took place at the proto-Andean margin of Gondwana in the Cambrian and the Ordovician, i.e., the Pampean (545-520 Ma) and Famatinian (490-440 Ma) orogenies, respectively. Between them, an extensive continental platform was developed, where mixed carbonate-siliciclastic sedimentation occurred. This platform was later involved in the Famatinian orogeny when it underwent penetrative deformation and metamorphism. The platform apparently extended from Patagonia to northwestern Argentina and the Eastern Sierras Pampeanas, and has probable equivalents in SW Africa, Peru, and Bolivia. The WSP record the outer (deepest) part of the platform, where carbonates were deposited in addition to siliciclastic sediments. Detrital zircon U-Pb SHRIMP ages from clastic metasedimentary successions and Sr-isotope compositions of marbles from the WSP suggest depositional ages between ca. 525 and 490 Ma. The detrital zircon age patterns further suggest that clastic sedimentation took place in two stages. The first was sourced mainly from re-working of the underlying Neoproterozoic metasedimentary rocks and the uplifted core of the early Cambrian Pampean orogen, without input from the Paleoproterozoic Río de la Plata craton. Sediments of the second stage resulted from the erosion of the still emerged Pampean belt and the Neoproterozoic Brasiliano orogen in the NE with some contribution from the Río de la Plata craton. An important conclusion is that the WSP basement was already part of SW Gondwana in the early Cambrian, and not part of the exotic Precordillera/Cuyania terrane, as was previously thought. [ABSTRACT FROM AUTHOR]

Graphite-rich metamorphic limestones included within low-grade black schists of the lowest Nevado-Filábride tectonic unit in the Sierra de Baza (Bodurria Unit) provided the first conodonts found in this complex (Declinognathodus bernesgae, D. inaequalis. D. cf. praenoduliferus, and Idioprioniodus sp.). This demonstrates the early Bashkirian age of the sedimentary protoliths, and their deposition in open marine anoxic environments of a continental margin that opened towards the E and that was related to the Palaeotethys. This breakthrough offers strong support for the hypothesis that the lower Nevado-Filábride units show stratigraphic and palaeogeographic affinities with the external domains of the Iberian Massif (Palentian Domain of the Cantabrian Zone in particular). Consequently, this part of the Betic Internal Zones must be related to the basement of the South-Iberian Palaeomargin and excluded from the Alborán Domain tectonostratigraphic terrane. [ABSTRACT FROM AUTHOR]

The Ediacaran-Ordovician Meguma Supergroup was thrust over Avalonia basement prior to the intrusion of post-Acadian, ca. 370 Ma, S-type granitic batholiths. This has led to two main hypotheses regarding the original location of the Meguma terrane, a continental rise prism bordering either NW Africa or Avalonia. On the other hand, the pre-Acadian, ca. 440 Ma Brenton pluton has yielded the following U/Pb LA-ICP-MS zircon data: (1) 448 ± 3 Ma population peak inferred to be the intrusive age and (2) ca. 550 and 700 Ma inherited ages common to both Avalonia and NW Africa. In contrast, Hf isotopic analyses of zircon yielded model ages ranging from 814 to 1127 Ma with most between 940 and 1040 Ma: such ages are typical of Avalonia and not NW Africa. The ages of the inherited zircons found within the Brenton pluton suggest that it was probably derived by partial melting of sub-Meguma, mid-crustal Avalonian rocks, upon which the Meguma Supergroup was deposited. Although Avalonia is commonly included in the peri-Gondwanan terranes off NW Africa or Amazonia, paleomagnetic data, faunal provinciality, and Hf data suggest that, during the Ediacaran-Early Cambrian, it was an island chain lying near the tropics (ca. 20-30 °S) and was possibly a continuation of the Bolshezemel volcanic arc accreted to northern Baltica during the Ediacaran Timanide orogenesis. This is consistent with the similar derital zircon population in the Ediacaran-Cambrian Meguma Supergroup and the Dividal Group in northeastern Baltica. [ABSTRACT FROM AUTHOR]

LA-ICP-MS U-Pb data from detrital zircons of the Ediacaran to Cambrian siliciclastic sequence of the Torgau-Doberlug Syncline (TDS, Saxo-Thuringia, Germany) are reported for the first time. The majority of 203 analysed zircon grains is Proterozoic with minor amount of Archean and Palaeozoic grains. The U-Pb ages fall into three groups: 2.8-2.4 Ga (3%), Neoarchean to earliest Palaeoproterozoic; 2.3-1.6 Ga (46%), early to late Palaeoproterozoic; 1.0-0.5 Ga (47%), Neoproterozoic to Cambrian. This age distribution is typical for the West African Craton as the source area and for Cadomian orogenic events in northwestern Gondwana. The samples show an age gap between 1.6 and 1.0 Ga, which is characteristic for West African provenance and diagnostic in distinguishing this unit from East Avalonia and Baltica. The dataset shows clusters of Palaeoproterozoic ages at 2.2-1.7 Ga, that is typical for western Gondwana, which was affected by abundant magmatic intrusions (ca. 2.2-1.8 Ga) during the Eburnean orogeny (West African craton). Neoarchean zircon ages (3%) point to recycling of magmatic rocks formed during the Liberian and Leonian orogenies. Ediacaran to earliest Cambrian rocks of the TDS originated in an active margin regime of the Gondwanan shelf. The following early Palaeozoic overstep sequence was deposited within rift settings that reflects instability of the West-Gondwanan shelf and the separation of terranes from Ordovician onward. The results of this study demonstrate distinct northwestern African provenance of the Cambrian siliciclastics of the TDS. Due to Th-U ratios from concordant zircon analysis, igneous origin from felsic melts is concluded as the source of these grains. [ABSTRACT FROM AUTHOR]

The Muang Xai Basin, located in northern Laos, is associated with the Simao, Vientiane, and Khorat Basins. The paleogeographic link of these basins has not been investigated in great detail; thus, the investigation presented in this study is a comprehensive analysis of petrology, whole-rock geochemistry, and detrital zircon U-Pb chronology used to characterize the provenance of the Muang Xai Basin. Results suggest that the sedimentary source includes felsic rocks from an active continental margin or continental arc with minor amounts of recycled passive continental margin sediments. Sandstones of the Muang Xai Basin contain detrital zircons with varying U-Pb peak ages. The youngest age peak of all the zircons is 103 Ma, which limits the age of the Mesozoic strata to the Late Cretaceous. Detrital zircon U-Pb and trace element data, combined with geochemical result, reveal that the pre-Ordovician zircons were derived from recycled sediments of the Yangtze Block, which are originally sourced from the Qinling Orogenic belt. This provenance is shared with coeval sediments in the Simao and Khorat Basins, while magmatic rocks of the Ailaoshan, Truong Son Belt, and Lincang terrane are responsible for zircons of 416-466 and 219-308 Ma in age. Zircons of 101-110 and 149-175 Ma in age were sourced from magmatic rocks of the southwestern South China Block and northern Vietnam. These provenance results suggest that sediments flow into the Khorat red beds was likely from the Great Simao Basin and northern Vietnam, and not directly from the Yangtze Block. [ABSTRACT FROM AUTHOR]

The lack of Early Cretaceous magmatic records with high-quality geochemical data in the southern Qiangtang subterrane has inhibited a complete understanding of the magmatic processes and geological evolution of central Tibet. In this study, we present zircon U-Pb ages, whole-rock geochemistry, and Sr-Nd-Pb and zircon Hf isotopic data for the newly discovered Moku pluton in the southern Qiangtang subterrane. Zircon U-Pb dating reveals that the Moku granites were emplaced in the Early Cretaceous (ca. 100 Ma) and are coeval with the hosted dioritic enclaves. The granites are slightly peraluminous and high-K calc-alkaline I-type granites and characterized by initial (Sr/Sr) ratios of 0.70605-0.70658, negative ε ( t) values (−4.44 to −3.35), and Nd isotopic model ages of 1.19-1.29 Ga. The granites have a wide range of zircon ε ( t) values (−24.4 to 2.6) and concordant ratios of (Pb/Pb) = 18.645-18.711, (Pb/Pb) = 15.656-15.666, and (Pb/Pb) = 38.751-38.836. The coeval dioritic enclaves are medium- to high-K calc-alkaline rocks with zircon ε ( t) values of −13.3 to +3.6. The geochemical signatures of the host granites and coeval dioritic enclaves indicate that the Moku pluton was most likely generated by partial melting of the ancient lower crust with contributions from mantle-derived melts. Our new data, together with other recently published data, indicate that the ca. 100 Ma magmatic rocks were derived from anatexis of the Qiangtang lower crust that mixed with upwelling asthenosphere materials in response to the slab break-off of the northward subduction of the Bangong-Nujiang oceanic lithosphere. [ABSTRACT FROM AUTHOR]

Marine carbonate ooids are environment-sensitive and hence valuable for paleoclimatic and paleogeographic reconstructions. This paper describes Permian ooids from the Baoshan Block in western Yunnan, China, in order to offer a new means to refine the uncertain paleogeographic details of this Gondwana-derived block. Four major types of ooids (micritic ooids, compound ooids, leached ooids and half-moon ooids) are documented from the Hewanjie Formation in the northern and the Shazipo Formation in the southern Baoshan Block. These ooids are dated via biostratigraphic analysis to be Wordian-early Wuchiapingian and signify an ameliorated shallow-marine temperature for the Guadalupian strata of the Baoshan Block. Results of this study, coupled with literature data, reveal diachronous debut of Permian ooids among the Gondwana-derived blocks: mostly Sakmarian in Central Taurides of Turkey, Central Iran, Central Pamir and Karakorum Block versus Wordian-Capitanian in Baoshan Block, Peninsular Thailand and South Qiangtang. In contrast, Asselian-Sakmarian strata of Baoshan Block as well as Peninsular Thailand and South Qiangtang are characterized by glaciomarine diamictites. These observations suggest that the Baoshan Block was probably situated at a considerably higher paleolatitude under distinct influence of Gondwana glaciation during the Asselian-Sakmarian than those blocks yielding Sakmarian ooids. Moreover, marine ooids are virtually absent nearby the equator within the Permian Tethys, similar to the modern situation. The Baoshan Block is accordingly interpreted to drift to warm-water southern mid-latitudes during the Wordian-Capitanian and remain to the south of Central Iran, Karakorum Block and South China, which were equatorially located in the Capitanian. [ABSTRACT FROM AUTHOR]

The presence of the Bashkirian-Moscovian (lower Pennsylvanian) sequence with mixed siliciclastics and fossil-rich carbonates has long been known from the Sanandaj-Sirjan Zone in Iran. However, except for a few studies, its biostratigraphy was not previously investigated in detail. A fusulinoid fauna is recovered from newly measured section, which we named the Asad Abad II section. It is located near the Shahreza town in the Sanandaj-Sirjan Zone. The most important fusulinoids of this assemblage are Aljutovella cf. aljutovica Rauser-Chernosouva, Tikhonovichiella tikhonovichi (Rauser-Chernosouva), and Profusulinella (Depratina) prisca (Deprat); they occur in association with species of Ozawainella, Staffellaeformis, and Pseudostaffella. This fauna overall represents a fauna of the latest Bashkirian-earliest Moscovian transition period in the Sanandaj-Sirjan Zone. This new fusulinoid fauna shares some common species with the concurrent faunas of the Alborz, East Iran, and Central Iran. Furthermore, it can be easily compared with those of the Russian Platform, Southern and Northern Urals, and Central Taurides (Turkey). The four species of the current fauna, namely Eostaffella compressa Brazhnikova, E. primitiva (Dutkevich), Pseudostaffella timanica Rauser-Chernosouva, and Profusulinella postpararhombiformis Dzhenchuraeva are reported from Iran for the first time. This study also presents the first occurrence of the genera Aljutovella and Tikhonovichiella in the Sanandaj-Sirjan Zone of Iran. [ABSTRACT FROM AUTHOR]

In placing Japanese tectonics in an Asian context, variation in the Paleozoic geological environment is a significant issue. This paper investigates the geochemistry of the lower Paleozoic basalt formation (Iwatsubodani Formation) in the Hida Gaien belt, Japan, to consider its tectonic setting. This formation includes the following two types of rock in ascending order: basalt A with sub-ophitic texture and basalt B with porphyritic texture. Basalt A has a high and uniform FeO*/MgO ratio, moderate TiO, high V, and low Ti/V. The HFSE and REE are nearly the same as those in MORB, and all the data points to basalt A being the 'MORB-like fore-arc tholeiitic basalt (FAB)' reported, for example, from the Izu-Bonin-Mariana arc. By contrast, basalt B has a low FeO*/MgO ratio, low TiO, and low V and Ti/V. It has an LREE-enriched trend and a distinct negative Nb anomaly in the MORB-normalized multi-element pattern and a moderately high LREE/HREE. All these factors suggest that basalt B is calc-alkaline basalt. It is known that FAB is erupted at the earliest stage of arc formation-namely, subduction initiation-and that boninitic/tholeiitic/calc-alkaline volcanism follows at the supra-subduction zone (SSZ). Thus, the occurrence of basalts A (FAB) and B (calc-alkaline rock) is strong evidence of early Paleozoic arc-formation initiation at an SSZ. Evidence for an early Paleozoic SSZ arc is also recognized from the Oeyama, Hayachine-Miyamori, and Sergeevka ophiolites. Hence, both these ophiolites and the Iwatsubodani Formation probably coexisted in a primitive SSZ system in the early Paleozoic. [ABSTRACT FROM AUTHOR]

Two Gondwana-derived Paleozoic belts rim the Archean/Paleoproterozoic nucleus of the East European Platform in the Black Sea region. In the north is a belt of Paleozoic passive-margin-type sedimentary rocks, which extends from Moesia to the Istanbul Zone and to parts of the Scythian Platform (the MOIS Block). This belt constituted the south-facing continental margin of the Laurussia during the Late Paleozoic. This margin was deformed during the Carboniferous by folding and thrusting and forms the Variscan foreland. In the south is a belt of metamorphic and granitic rocks, which extends from the Balkanides through Strandja, Sakarya to the Caucasus (BASSAC Block). The protoliths of the metamorphic rocks are predominantly late Neoproterozoic granites and Paleozoic sedimentary and igneous rocks, which were deformed and metamorphosed during the Early Carboniferous. There are also minor eclogites and serpentinites, mostly confined to the northern margin of the BASSAC Block. Typical metamorphism is of low pressure-high temperature type and occurred during the Early Carboniferous (Visean, 340-330 Ma) coevally with that observed in the Central Europe. Volumetrically, more than half of the crystalline belt is made up of Carboniferous-earliest Permian (335-294 Ma) granites. The type of metamorphism, its concurrent nature over 1800 km length of the BASSAC Block and voluminous acidic magmatism suggest that the thermal event probably occurred in the deep levels of a continental magmatic arc. The BASSAC arc collided with Laurussia in the mid-Carboniferous leading to the foreland deformation. The ensuing uplift in the Permian resulted in the deposition of continental red beds, which are associated with acidic magmatic rocks observed over the foreland as well as over the BASSAC Block. In the Black Sea region, there was no terminal collision of Laurussia with Gondwana during the Late Paleozoic and the Laurussia margin continued to face the Paleo-Tethyan ocean in the south. [ABSTRACT FROM AUTHOR]

Since the Belize coast was repeatedly affected by hurricanes and the paleohurricane record for this region is poor, sediment cores from coastal lagoon environments along the central Belize coast have been examined in order to identify storm deposits. The paleohurricane record presented in this study spans the past 8000 years and exhibits three periods with increased evidences of hurricane strikes occurring at 6000-4900, 4200-3600 and 2200-1500 cal yr BP. Two earlier events around 7100 and 7900 cal yr BP and more recent events around 180 cal yr BP and during modern times have been detected. Sand layers, redeposited corals and lagoon shell concentrations have been used as proxies for storm deposition. Additionally, hiatuses and reversed ages may indicate storm influence. While sand layers and corals represent overwash deposits, the lagoon shell concentrations, which mainly comprise the bivalve Anomalocardia cuneimeris and cerithid gastropods, have been deposited due to changes in lagoon salinity during and after storm landfalls. Comparison with other studies reveals similarities with one record from Belize, but hardly any matches with other published records. The potential for paleotempestology reconstructions of the barrier-lagoon complexes along the central Belize coast differs depending on geomorphology, and deposition of washovers in the lagoon basins is limited, probably due to the interplay of biological, geological and geomorphological processes. [ABSTRACT FROM AUTHOR]

Smectite is typically considered unsuitable for radiometric dating, as argon (Ar) produced from decay of exchangeable potassium (K) located in the interlayer sites can be lost during fluid-rock interaction and/or during wet sample preparation in the laboratory. However, age analysis of Late Cretaceous Argentinian bentonites and associated volcaniclastic rocks from Lago Pellegrini, Northern Patagonia, indicates that, in the case of these very low-permeability rocks, the radioactive Ar was retained and thus can provide information on smectite age and the timing of rock alteration. This study presents isotopic results that indicate the ash-to-bentonite conversion and alteration of the overlying tuffaceous mudstones in Northern Patagonia was complete ~13-17 my after middle Campanian sedimentation when the system isotopically closed. The general absence of illite in these smectite-rich lithologies reflects the low activity of K and the low temperature (<60 °C) of the formation waters that altered the parent ash. [ABSTRACT FROM AUTHOR]

Fusha structural belt (FSB) is one of the most important tectonic units in front of the Western Kunlun Orogen, northwestern Tibetan Plateau (NW China), in which the Kekeya oil field was discovered in 1971. However, there is no new oil field discovered since then due to the unclarity of the intense and complex Cenozoic deformation in this area. Based on field investigation, seismic interpretation and Continuous Electromagnetic Profile data, we analyze in detail the Cenozoic deformation history, emphasizing on the spatial and temporal variation of the deformation of the FSB in this paper. The result suggests that the FSB was dominated by two deformation events, (1) early (Miocene-early Pliocene) folding event expressed by anticline, with the western segment E-W orienting, while the eastern segment NWW-SEE orienting and (2) later (since late Pliocene) transpressional faulting event that destroyed and divided the earlier anticline into a number of fault blocks. The transpressional faulting caused dextral strike-slip reverse fault, with the dip angles decreasing eastward from ~90° to <45°. The dextral strike-slip reverse fault developed in the core of the anticline in the western part which caused the anticline into several fault blocks, while in the eastern part, the fault developed in the north limb of the anticline with the core of the anticline reserved. Based on the spatial variation of structural characteristics, we propose that the fault block traps and anticline traps in the eastern segment and fault block traps in western segment are favorable for hydrocarbon accumulation. [ABSTRACT FROM AUTHOR]

New geochronological, geochemical, and isotopic data are reported for the Capilla del Monte two-mica granite pluton in the northeastern Sierras de Córdoba. An Early Carboniferous age is established by a U-Pb zircon concordia (336 ± 3 Ma) and a Rb-Sr whole-rock isochron (337 ± 2 Ma). Zircon saturation geothermometry indicates relatively high temperatures (735-800 °C). The granites have high average SiO (74.2 %), NaO + KO (7.8 %), and high field-strength elements, high KO/NaO (1.7) and FeO/MgO ratios (5.1), with low CaO content (0.71 %). REE patterns with marked negative Eu anomalies (Eu/Eu* 0.14-0.56) indicate crystal fractionation, dominantly of plagioclase and K-feldspar, from a peraluminous magma enriched in F. Isotope data (Sr/Sr = 0.7086, ε = −5.5 to −4.4 with T = 1.5 Ga, zircon ε +0.8 to −6.1; mean T = 1.5 Ga) suggest a Mesoproterozoic continental source, albeit with some younger or more juvenile material indicated by the Hf data. The pluton is the easternmost member of a Carboniferous A-type magmatic suite which shows an increase in juvenile input toward the west in this part of the pre-Andean margin. The petrological and geochemical data strongly suggest a similar intraplate geodynamic setting to that of the nearby but much larger, Late Devonian, Achala batholith, although Hf isotope signatures of zircon suggest a more uniformly crustal origin for the latter. Further studies are required to understand whether these bodies represent two independent magmatic episodes or more continuous activity. [ABSTRACT FROM AUTHOR]

The Roer Valley Graben is a Mesozoic continental rift basin that was reactivated during the Late Oligocene. The study area is located in the graben area of the southwestern part of the Roer Valley Graben. Rifting initiated in the study area with the development of a large number of faults in the prerift strata. Some of these faults were rooted in preexisting zones of weakness in the Mesozoic strata. Early in the Late Oligocene, several faults died out in the study area as strain became focused upon others, some of which were able to link into several-kilometer-long systems. Within the Late Oligocene to Early Miocene northwestward prograding shallow marine syn-rift deposits, the number of active faults further decreased with time. A relatively strong decrease was observed around the Oligocene/Miocene boundary and represents a further focus of strain onto the long fault systems. Miocene extensional strain was not accommodated by further growth, but predominantly by displacements along the long fault systems. Since the Oligocene/Miocene boundary coincides with a radical change in the European intraplate stress field, the latter might have contributed significantly to the simultaneous change of fault kinematics in the study area. [ABSTRACT FROM AUTHOR]

We present the results of paleomagnetic study of Ediacaran sedimentary successions from the Southern Urals. The analysis of the sedimentary rocks of the Krivaya Luka, Kurgashlya and Bakeevo Formations reveal stable mid-temperature and high-temperature remanence components. Mid-temperature components were acquired during Devonian (Bakeevo Formation) and Late Carboniferous-Early Permian remagnetization events. The high-temperature components in Kurgashlya and Bakeevo Formations are interpreted to be primary, because they are supported by a positive conglomerate test (Bakeevo Formation) and magnetostratigraphic pattern (Kurgashlya Formation). The high-temperature component in the Krivaya Luka Formation is interpreted to be a Late Ediacaran overprint. Our new paleomagnetic poles together with some previously published Ediacaran poles from Baltica and Laurentia are used herein to produce a series of paleogeographic reconstructions of the opening of the Iapetus Ocean. [ABSTRACT FROM AUTHOR]