Coastal Outcrops Research Articles

ПАЛЕОМАГНЕТИЗМ И ПЕТРОХИМИЯ ПЕСЧАНИКОВ ГОРИНСКОЙ И ПИОНЕРСКОЙ СВИТ ЖУРАВЛЕВСКО-АМУРСКОГО ТЕРРЕЙНА (СЕВЕРНЫЙ СИХОТЭ-АЛИНЬ)

The first paleomagnetic and petrochemical data on the Lower Cretaceous sedimentary rocks of the Komsomolsk Series from the Zhuravlevka–Amurian turbidite paleobasin are presented. The rocks are collected in coastal outcrops of Sakhalin Bay (54.09° N, 140.05° E). The studies reveal that (1) the petrochemical characteristics of the sedimentary rocks of the Gorinskaya and Pionerskaya formations (Berriasian–Valanginian) do not contradict the model of their formation in a setting of the transform continental margin; (2) the paleolatitude at which they attained pre-folding paleomagnetic direction (Dec = 303°, Inc = 27°, Ks/Kg = 6.2) was 10–18° N; (3) in the post-Valanginian time, before 95 Ma B.P., the block including these rocks moved northward by 3900–4800 km along the Eurasian transform continental margin at a mean rate of about 10–13 cm/yr.

Physical-biological interactions in the ocean: case studies from the northern Canary Current Upwelling Ecosystem

Physical-biological interactions in the ocean: case studies from the northern Canary Current Upwelling Ecosystem

Provenance analyses of the heavy-mineral beach sands of the Annaba coast, northeast Algeria, and their consequences for the evaluation of fossil placer deposit

The paper presents the first study of heavy-mineral sand beaches from the Mediterranean coast of Annaba/Algeria. The studied beaches run along the basement outcrops of the Edough massif, which are mainly composed by micaschists, tourmaline-rich quartzo-feldspathic veins, gneisses, skarns and marbles. Sand samples were taken from three localities (Ain Achir, Plage-Militaire and El Nasr). The heavy-mineral fraction comprises between 74 and 91 vol%. The garnets of the beaches are almandine rich and tourmalines vary with respect to their location from schorl to dravite. Tourmaline at Ain Achir and the Plage-Militaire is schorlits, while at El Nasr beach dravite is ubiquitous. The World Shale Average normalised REE of the sands and the basement outcrops reveal: (i) Ain Achir beach: REE pattern of sand and the coastal rocks from the studied beaches reflects a multiple sources; (ii) Plage-Militaire: the sand and the coastal outcrops show similar LREE and a strong enrichment in HREE, suggesting the presence HREE-rich phases found as inclusions in staurolite; (iii) El Nasr: two types of sand patterns are found: one with flat REE pattern similar to the proximal rocks and other one enriched in HREE suggesting a mixed source.

New insights from microfauna associations characterizing palaeoenvironments, sea level fluctuations and a tsunami event along Sfax Northern coast (Gulf of Gabes, Tunisia) during the Late Pleistocene-Holocene

Late Pleistocene to Holocene evolution of the Northern coast of Sfax (Gulf of Gabes, Tunisia) is deduced on the basis of the analyses of sediment cores and coastal outcrops. The environmental changes are established by means of microfauna and mollusk assemblages and biocenotic parameters complemented by geochemical, sedimentological and correspondence analysis (CA). An opened embayment, rich in warm Senegalese fauna, allowed the deposition of quartz-rich sands Late Pleistocene in age. During the Late Holocene, a major modification of the environmental characters is recognized. The dominance of marine ostracod and coastal foraminifera coupled with high values of species richness characterize a widely opened lagoon. This lagoon is subjected to the action of the alongshore drifts which are responsible for the build-up of sand spits and the genesis of the present sebkhas. Two transgressive events, overlying the marine Late Pleistocene quartz-rich sands, are dated at 2018–2419 and 1001–1804 a cal BP. The dominance of marine and coastal foraminifera, the recurrence of ostracods and the high values of biocenotic parameters testify these two events. Sudden changes, toward 0–502 a cal BP, in the structure of populations, geochemical element concentrations and sedimentological trend argue in favor of a tsunami event and the settlement of peculiar environment. The latter records (1) the reworking of Holocene microfauna and Tyrrhenian sands rich in mollusks eroded from the marine substrata; (2) the high concentration of poorly stratified and poorly sorted shells; (3) fining-upward and thinning landward sequences; (4) the dominance of articulated bivalves and sharpened shells; and (5) the locally extensive deposits up to 160 m inland rising in altitude of about 0.75 m. This extreme event can be correlated with the tsunami generated by the strong earthquake, 1908 AD in age, in Eastern Sicily or by one of the earthquakes recorded during the 18th Century around the Mediterranean basin such as Sfax earthquake of 1750 AD.

Heavy metals in coastal sediments of South Caspian Sea: natural or anthropogenic source?

This paper focuses on heavy metal distribution patterns in sediments of central Guilan (CG) and east Mazandaran (EM) in the south Caspian Sea coasts, north of Iran. Sediment sub-samples were retrieved from core and surficial samples in different environments of marine and coastal lagoons as well as coastal outcrops. Inductively Coupled Plasma Mass Spectrometry and Atomic Emission Spectrometry (ICP-MS and ICP-AES) analysis were used to determine the metal chemistry. Concentration of the selected heavy metals exhibited variations through sediment samples which are partially related to grain size and organic matter content. Geoaccumulation index and statistical procedures have been implemented for analyzing the absolute metal values. Result of the geoaccumulation index demonstrated that the metal distribution reflects the influence of geological background of the watershed area. Some elements including Pb, Ni, Cu, Sr and Ba showed elevated concentration in the CG that could be attributed to development of industrial activities. A comparison of the metal concentration in the marine sediments and the Late Holocene outcrops revealed that the level of the metals concentration at the sea generally corresponds to natural background. The northern part of Iranian multi-lithological catchments basin is the main source for the sediments that drained by the rivers to the South Caspian Sea basin

Reprint of 'Unusual geologic evidence of coeval seismic shaking and tsunamis shows variability in earthquake size and recurrence in the area of the giant 1960 Chile earthquake'

An uncommon coastal sedimentary record combines evidence for seismic shaking and coincident tsunami inundation since AD 1000 in the region of the largest earthquake recorded instrumentally: the giant 1960 southern Chile earthquake (Mw 9.5). The record reveals significant variability in the size and recurrence of megathrust earthquakes and ensuing tsunamis along this part of the Nazca-South American plate boundary. A 500-m long coastal outcrop on Isla Chiloé, midway along the 1960 rupture, provides continuous exposure of soil horizons buried locally by debris-flow diamicts and extensively by tsunami sand sheets. The diamicts flattened plants that yield geologically precise ages to correlate with well-dated evidence elsewhere. The 1960 event was preceded by three earthquakes that probably resembled it in their effects, in AD 898–1128, 1300–1398 and 1575, and by five relatively smaller intervening earthquakes. Earthquakes and tsunamis recurred exceptionally often between AD 1300 and 1575. Their average recurrence interval of 85years only slightly exceeds the time already elapsed since 1960. This inference is of serious concern because no earthquake has been anticipated in the region so soon after the 1960 event, and current plate locking suggests that some segments of the boundary are already capable of producing large earthquakes. This long-term earthquake and tsunami history of one of the world's most seismically active subduction zones provides an example of variable rupture mode, in which earthquake size and recurrence interval vary from one earthquake to the next.

The wider context of the Lower Jurassic Toarcian oceanic anoxic event in Yorkshire coastal outcrops, UK

The Toarcian Oceanic Anoxic Event (T-OAE, ∼183Ma) was characterized by enhanced carbon burial, a prominent negative carbon-isotope excursion (CIE) in marine carbonate and organic matter, and numerous geochemical anomalies. A precursor excursion has also been documented at the Pliensbachian/Toarcian boundary, but its possible causes are less constrained. The T-OAE is intensively studied in the Cleveland Basin, Yorkshire, UK, whose sedimentary deposits have been litho-, bio- and chemostratigraphically characterised. Here, we present new elemental data produced by hand-held X-ray fluorescence analysis to test the expression of redox-sensitive trace metals and detrital elements across the upper Pliensbachian to mid-Toarcian of the Cleveland Basin. Detrital elemental concentrations (Al, Si, Ti, Zr) are used as proxies for siliciclastic grain content and thus, sea-level change, which match previous sequence stratigraphic interpretations from the Cleveland Basin. The timescale of the event is debated, though our new elemental proxies of relative sea level change show evidence for a cyclicity of 350cm that may be indicative of ∼405 kyr eccentricity cycles in Yorkshire. Trends in total organic carbon and redox-sensitive elements (S, Fe, Mo, As) confirm scenarios of widespread ocean deoxygenation across the T-OAE. The correlation of comparable trends in Mo across the T-OAE in Yorkshire and the Paris Basin suggests a similar oceanic drawdown of this element accompanying widespread anoxia in the two basins. Data from Yorkshire point to a transgressive trend at the time of the Mo drawdown, which contradicts the “basin restriction” model for the euxinic conditions that characterise the CIE interval.

The morphology and mode of formation of Neoeione igen. nov. from the Carboniferous of northern England

Samples of the burrows studied herein, originally introduced as Eione moniliformis Tate, have been collected from the heterolithic sandstone and siltstone beds of a coastal outcrop near the town of Howick, Northumberland, UK. These interbedded and hummocky cross-stratified beds, belonging to the Stainmore Formation, are Carboniferous and represent offshore marine sediment deposited between the fair wave base and storm wave base. As the name Eione was used previously to describe a genus of gastropod, Eione Tate is a junior homonym of Eione Rafinesque. Therefore, a new ichnogenus was established, Parataenidium Buckman, to accommodate burrows composed of two distinct levels, which included E. moniliformis. Using three-dimensional morphological modeling techniques, this study aims to: (1) clarify the current taxonomic status of Parataenidium moniliformis; and (2) provide an updated model for its construction. The transfer of E. moniliformis to Parataenidium was problematic, primarily because it is not composed of two distinct levels, but, instead, is composed of backfilled reniform sediment packages. These packages were created through a multistage process whereby the organism maintained a small open cavity from which it fed. Accordingly, a new ichnogenus, Neoeione, is proposed to accommodate the material originally described by Tate.

Geochemistry of obsidian from Krasnoe Lake on the Chukchi Peninsula (Northeastern Siberia)

This report considers features of the geochemical composition of obsidian from beach sediments of Krasnoe Lake along the lower course of the Anadyr River, as well as from lava–pyroclastic rocks constituting the lake coastal outcrops and the surrounding branches of Rarytkin Ridge. The two geochemical types of obsidian, for the first time distinguished and researched, correspond in their chemical composition to lavas and ignimbrite-like tuffs of rhyolites from the Rarytkin area. The distinguished types represent the final stage of acidic volcanism in the West Kamchatkan–Koryak volcanic belt. It was assumed that the accumulation of obsidian in coastal pebble beds was caused by the erosion of extrusive domes and pyroclastic flows. The geochemical studies of obsidian artifacts from archeological sites of the regions of the Sea of Okhotsk, the Kolyma River, and the Chukchi Peninsula along with the correlation of geological and archeological samples show that Krasnoe Lake was an important source of “archeological” obsidian in Northeastern Siberia.

Fracture overprinting history using Markov chain analysis: Windsor-Kennetcook subbasin, Maritimes Basin, Canada

The deformation history of the Upper Paleozoic Maritimes Basin, Atlantic Canada, can be partially unraveled by examining fractures (joints, veins, and faults) that are well exposed on the shorelines of the macrotidal Bay of Fundy, in subsurface core, and on image logs. Data were collected from coastal outcrops and well core across the Windsor-Kennetcook subbasin, a subbasin in the Maritimes Basin, using the circular scan-line and vertical scan-line methods in outcrop, and FMI Image log analysis of core. We use cross-cutting and abutting relationships between fractures to understand relative timing of fracturing, followed by a statistical test (Markov chain analysis) to separate groups of fractures. This analysis, previously used in sedimentology, was modified to statistically test the randomness of fracture timing relationships. The results of the Markov chain analysis suggest that fracture initiation can be attributed to movement along the Minas Fault Zone, an E-W fault system that bounds the Windsor-Kennetcook subbasin to the north. Four sets of fractures are related to dextral strike slip along the Minas Fault Zone in the late Paleozoic, and four sets are related to sinistral reactivation of the same boundary in the Mesozoic.

Abundance, richness, and succession of microfungi in relation to chemical changes in Antarctic moss profiles

Little is known in continental Antarctic about patterns of abundance, diversity, and succession of microfungi within moss profiles consisting of live, senescent, and dead tissues in different stages of decomposition. In the present study, vertical patterns of the abundance and diversity of microfungi and their relationship with chemical compositions were examined within moss colonies collected from coastal outcrops in the Lutzow–Holm Bay area (Queen Maud Land), East continental Antarctica. Total and darkly pigmented hyphal length, the richness of molecular operational taxonomic units (MOTUs) of microfungi, and the occurrence of Phoma herbarum and Pseudogymnoascus pannorum increased with the depth of moss profiles. The content of organic chemical components and nitrogen in moss tissues decreased, whereas ash content increased with the depth of moss profiles. Relative amount of recalcitrant compounds and total carbohydrates did not significantly differ among the vertical layers. The downward increase of the microfungal richness and occurrence in the Antarctic moss profiles without MOTU replacement was consistent with the directional-nonreplacement model of succession, indicative of the high environmental resistance, which represents the sum of the adverse factors hindering the success of species establishment. This contrasted with the fungal succession in arctic moss profiles, which accorded with the directional-replacement model, in which species replacement took place due to modification of habitat and competition. More hostile environmental conditions than those in the Arctic characterized the fungal succession and limited the fungal decomposition of moss in continental Antarctica.

Effect of evaporite paleo-lacustrine facies on the brines geochemistry, economy implication. Case of chott Bagdad El Hadjira Ouargla, South-Eastern Algeria

The experimental investigation is a part of a wider research programme, addressed to valorisate the content of chott brine in south-est Algeria, by using multi disciplinary methods. This first paper reports on the analyses of paleo-lake deposits in Coastal outcrop of chott Baghdad, and their impact on the chemical composition of brines. The marginal paleo-lake deposits in the southern part of the chott Baghdad are dominated by gypsum formations and sandstones with in CaSO3 contents ranging between 49.2 and 85.8%. In general, chott Baghdad brine is supersaturated in ions (Ca2+, Mg2+, Na+, K+, HCO3-, SO42-, Cl-), and present a geochemical zone, within the northern and southern parts. The gypsum formations that approach chott are the important source of this chemical enrichment and spatial distribution.The brine northern part of the chott is essentially hyperchlorinated calcium. On the other hand, those of the southern end are chloride and magnesia. Therefore two types of salts are recoverable from these two natural brines:“Magnesium Salts” and “Chlorides Salts”

Deciphering the geology of some Darriwilian–Sandbian (Ordovician) ‘ghost’ formations in the UK and North America using olistoliths in marine debris flows

AbstractOlistostromes with calcareous olistoliths are rare components in the Ordovician successions in NW Europe and North America, having been described from only a small number of localities. One of the best exposed, but least known, is in the Garn Formation in coastal outcrops in Anglesey in northwestern Wales. Here, in the graptolite-bearing shales of the Garn Formation, there are numerous limestone olistoliths that are derived from an otherwise unknown ‘ghost’ formation whose original depositional site remains an enigma. These olistoliths contain a Baltoscandian type of conodont fauna that is otherwise unknown in Wales and England. It represents the Baltoniodus variabilis Subzone of the Amorphognathus tvaerensis Zone. Similar, but slightly older, conodont faunas are recorded from olistoliths in the Tweeddale Member of the Shinnel Formation in southern Scotland and in probable olistoliths of the Cobbs Arm Limestone in northeasternmost Newfoundland. Approximately coeval conodont faunas are present in calcareous olistoliths in the Woods Hollow Shale of West Texas and the Womble Shale in the Ouachita Mountains of Arkansas, USA. Lithological and conodont evidence indicates that the calcareous olistoliths were derived from carbonate sediments deposited in relatively shallow water. It is concluded that the study of ‘ghost’ formation olistoliths may provide otherwise unavailable but important data bearing on the marine depositional history of a particular region.

Stratigraphic reconstruction of the Strzelecki Group outcrops in west Gippsland: new data on the present-day thickness and amount of erosion

ABSTRACTThe Lower Cretaceous Strzelecki Group forms the basement to the eastern part of the Gippsland Basin, but is exposed in the west and forms spectacular outcrops, especially along the coastal area between San Remo and Inverloch. The coastal area is highly faulted and lacks stratigraphic markers so matching sections in different fault blocks based only on lithology has not been possible. A combination of mapping, detailed logging, vitrinite reflectance measurements and palynology were used to determine the present-day thickness of the coastal sections and the amount of erosion that occurred during the Late Cretaceous. A total thickness of about 1500 m is inferred between Harmers Haven and Inverloch but because of the amount of faulting and probable repeated sections, the true thickness of Strzelecki Group exposed in the coastal outcrops is only about 300 m. Based on palynology and vitrinite reflectance results, the reconstructed Strzelecki Group stratigraphy has been subdivided into three distinct ‘bio-blocks’, with an eroded section estimated to range from 1.5 km (0.3–2.6 km at ±95% confidence limits) to 2.7 km (2.2–3.1 km at ±95% confidence limits).

Unusual geologic evidence of coeval seismic shaking and tsunamis shows variability in earthquake size and recurrence in the area of the giant 1960 Chile earthquake

An uncommon coastal sedimentary record combines evidence for seismic shaking and coincident tsunami inundation since AD 1000 in the region of the largest earthquake recorded instrumentally: the giant 1960 southern Chile earthquake (Mw 9.5). The record reveals significant variability in the size and recurrence of megathrust earthquakes and ensuing tsunamis along this part of the Nazca-South American plate boundary. A 500-m long coastal outcrop on Isla Chiloé, midway along the 1960 rupture, provides continuous exposure of soil horizons buried locally by debris-flow diamicts and extensively by tsunami sand sheets. The diamicts flattened plants that yield geologically precise ages to correlate with well-dated evidence elsewhere. The 1960 event was preceded by three earthquakes that probably resembled it in their effects, in AD 898–1128, 1300–1398 and 1575, and by five relatively smaller intervening earthquakes. Earthquakes and tsunamis recurred exceptionally often between AD 1300 and 1575. Their average recurrence interval of 85years only slightly exceeds the time already elapsed since 1960. This inference is of serious concern because no earthquake has been anticipated in the region so soon after the 1960 event, and current plate locking suggests that some segments of the boundary are already capable of producing large earthquakes. This long-term earthquake and tsunami history of one of the world's most seismically active subduction zones provides an example of variable rupture mode, in which earthquake size and recurrence interval vary from one earthquake to the next.

Diversity and community assembly of moss-associated fungi in ice-free coastal outcrops of continental Antarctica

Abstract To date, the relative roles of niche-related (e.g., environmental filtering and biological interactions) and non-niche-related (e.g., dispersal limitation) processes in the assembly of fungal communities have rarely been explored in ice-free coastal outcrops of continental Antarctica. Here, using variation partitioning, we show that the community composition of fungi associated with moss colonies sparsely distributed in ice-free coastal outcrops of East Antarctica is affected by a suite of environmental conditions more significantly than by geographic distance, indicating the primary importance of niche-related factors. This was mainly attributable to the widespread occurrence of the predominant, cosmopolitan fungal species, Phoma herbarum . The variance explained by spatial factors increased when the analysis was applied only to the dataset of the Lutzow-Holm Bay area (by excluding the data of the Amundsen Bay area, which is 500 km from the Lutzow-Holm Bay area), indicating the local importance of non-niche-related processes.

Role of Recruitment Processes in Structuring Coralligenous Benthic Assemblages in the Northern Adriatic Continental Shelf.

Coralligenous biogenic reefs are among the most diverse marine habitats in the Mediterranean Sea. The northern Adriatic mesophotic coralligenous outcrops host very rich and diverse epibenthic assemblages. Several studies quantified the low temporal variability and high spatial heterogeneity of these habitats, while processes driving structuring and differentiation are still poorly understood. To shed light on these processes, temporal and spatial patterns of colonisation were investigated using travertine tiles deployed on three coralligenous outcrops, corresponding to the main typologies of benthic assemblages described in previous studies. Three years after deployment, assemblages colonising travertine tiles resembled the differentiation among sites revealed by the natural assemblages in terms of major ecological groups. Processes structuring and maintaining species diversity have been explored. Pioneer species with high reproduction rate, long distance larval dispersal and fast growth (e.g. the serpulid polychaete Spirobranchus triqueter and the bivalve Anomia ephippium), were the most abundant in the early stages of recruitment on the two outcrops further away from the coast and with lower sedimentation. Their success may vary according to larval availability and environmental conditions (e.g., sedimentation rates). At these sites early-stage lasted 10–12 months, during which even species from natural substrates began colonising tiles by settlement of planktonic propagules (e.g., encrusting calcareous Rhodophyta) and lateral encroachment (e.g., sponges and ascidians). On coastal outcrop, exposed to a higher sedimentation rates, tiles were colonised by fast-growing algal turfs. Resilience of northern Adriatic coralligenous assemblages, and maintenance of their diversity, appeared largely entrusted to asexual reproduction. Exploring the mechanisms that underlie the formation and maintenance of the species diversity is crucial to improve our understanding of ecological processes and to implement appropriate conservation strategies of the Adriatic coralligenous reefs.

Middle to Late Pleistocene topography evolution of the North-Eastern Azov region

The structure of loess-soil sequences of the North-Eastern Azov region was studied in coastal outcrops and boreholes within four key areas of the terraces of different age. Based on the positions of paleosols in geological sections of interfluve areas, the palaeotopography during interglacial epochs of the last 500 ka was reconstructed. The analysis of the topography evolution showed that the most significant features of the primary fluvial-marine relief remained in subaerial stage of the surface development and were inherited even in modern relief. At the same time, in subaerial stage the surface of interfluves experienced considerable reworking due to loess accumulation, on the one hand, and erosion, on the other hand. It has been established that these processes were controlled by the glacial-interglacial climatic cycles; however, their intensity varied from cycle to cycle. Generally, before the Valdai (Weichselian) glacial epoch, loess accumulation prevailed on the interfluve areas. The intensity of erosion at that time was relatively low. During the Valdai epoch (by indirect evidence, during its final stage, MIS 2, ∼29–12 ka), a phase of exceptionally intensive erosion was detected. Due to it, linear erosion and slope processes developed even within fairly gently slope (2–4°) areas. It has been determined that during this time, the upper parts of gullies were growing rapidly towards watersheds. In the modern topography, a branched pattern of relic hollows inherits their position.

U–Pb Zircon (SHRIMP) ages of granite sheets and timing of deformational events in the Natal Metamorphic Belt, southeastern Africa: Evidence for deformation partitioning and implications for Rodinia reconstructions

This study provides constraints on the ages of deformation events and fabric development in deformed rocks of the Margate Terrane of the Natal Metamorphic Province. The Margate Terrane forms the southernmost of three terranes considered to represent multiple arc accretion onto the southern margin of the Kalahari Craton, and geochronological data indicate that the Margate Terrane has a long history of sporadic magmatism from ∼1180 to ∼1025Ma. Two granite sheets of differing structural age, as revealed by deformational fabric and cross-cutting relationships, were sampled for U–Pb (SHRIMP) dating from coastal outcrop at Southbroom (30°54′43.61″S, 30°20′1.61″E). The older sheet contains fabrics related to both D1 and D2 events, whereas the younger shows evidence for syn-D2 emplacement and contains an S2 fabric. For both intrusive sheets, zircon core domains showing magmatic zoning yielded ages that are statistically identical at 1075±6Ma. This is interpreted to represent the intrusion age of the older sheet, and to sampling of a xenocrystic population in the cross-cutting sheet due to assimilation. Zircons from both sheets show metamorphic rim zones with a mean age of 1042±10Ma, which is attributed to rim growth during development of the S2 foliation, close to the intrusion age of the younger sheet. The 1075±6Ma age is comparable to the ages of other granitic units in the Margate Terrane that intruded between ∼1091 and 1070Ma and implies that all of these predated the D1 deformation, which is considered to record the accretion of the terrane onto the Kalahari Craton. The D2 event is characterized by northward-verging folds with a pervasive southward-dipping axial planar fabric S2, which largely overprinted the S1 fabric. Previously, the pure-shear D2 deformation was considered to be older than the narrow sinistral shear zones occurring within the Mzumbe and Margate Terranes. However, dating of the D2 event at 1042±10Ma indicates that these deformations are coeval, and represent deformation partitioning during a transpressional event at ∼1050–1025Ma that may have been related to collision with Laurentia during the amalgamation of Rodinia.

Phylogenetic relationships within the relict family Eomeropidae (Insecta, Mecoptera) based on the oldest fossil from the Early Jurassic (Sinemurian) of Dorset, southern England

The family Eomeropidae is a peculiar relict family of Mecoptera with a single extant species and, until now, eight known fossil species ranging in age from Middle Jurassic to Palaeogene. The oldest representative of the family, Jurachorista bashkuevi gen. et sp. nov., was collected from a coastal outcrop in Dorset, southern England, and is described herein. It extends the fossil record of Eomeropidae back to the Sinemurian (Early Jurassic; c. 196 Ma) and sheds new light on the phylogenetic relationships and past distribution of the family. Analysis of the wing venation of all known Eomeropidae indicates that Notiothauma reedi, the only living representative, is characterized by the most polymerized wings, while the oldest species, the newly described Jurachorista bashkuevi, has the most reduced venation within the family. Phylogenetic analysis based on wing venation produces a tree with two clades, illustrating the different taxonomic lines within the family.http://zoobank.org/urn:lsid:zoobank.org:pub:9CFA9133-6B64-4BF1-954C-C6A52D17F125