Limestone Member Research Articles

A Neognathodus-based biozonation of the Desmoinesian Series (Pennsylvanian) in the Illinois Basin, USA

AbstractThe Neognathodus Index (NI) is developed as a primary biostratigraphic indicator for the Desmoinesian Series of the Illinois Basin in Indiana, Illinois, and Kentucky. It is based on the gradual evolutionary morphotypic variations of P1 elements of named species of Neognathodus Dunn, 1970. The NI analyses and zonations presented herein are constructed from 472 productive conodont samples from 105 different localities. NIs for the Illinois Basin show morphologic drift in Indiana from the Perth Limestone Member of the Staunton Formation (NI = 2.03) to the Velpen Limestone and Mecca Quarry Shale members of the Linton Formation (NI = 5.04) followed by stability through the Alum Cave (NI = 4.83). Further morphologic drift then occurred through the Providence Limestone Member of the Dugger Formation (NI = 5.43) and continued through the West Franklin Limestone Member of the Shelburn Formation (NI = 6.32) until the extinction of Neognathodus at the end of Desmoinesian. The patterns of drift and stability translate to Neognathodus biozones and are supported by Kolmogorov-Smirnov tests of standardized Neognathodus morphotype distributions. Localized NI variations are due to morphologic shifts and differential evolution in response to localized environmental conditions. Examination of the NI differences in the states of Illinois, Kentucky, and Indiana reflect similar morphologic simplification of the P1 element from Perth to Velpen and Mecca Quarry in Indiana (NI = 2.03–5.04) and from Seville to Brereton in Illinois and Kentucky (NI = 2.80–5.00). Post-Brereton in Illinois and Kentucky (NI = 5.00–5.65) and post-Providence in Indiana (NI = 5.43–6.32) saw progressive P1 simplification, but it was much more pronounced in Indiana.

Campanian–Maastrichtian unconformities and rudist diagenesis, Aruma Formation, central Saudi Arabia

The Upper Cretaceous Aruma Formation is widely distributed in central Saudi Arabia and consists of three members, from base to top, the Khanasir Limestone Member, the Hajajah Limestone Member, and the Lina Shale Member. It disconfomably overlies the Cenomanian Wasia Formation (middle Turonian, the “Wasia-Aruma break”). Two unconformities were recorded within and at the top of the Aruma Formation: (a) “the lower Campanian unconformity” between the Khanasir Limestone Member and the Hajajah Limestone Member and (b) “the pre-Cenozoic unconformity” between the Lina Shale Member and the Paleogene Umm er Radhuma Formation. The comparison between these unconformities and those recorded on the Arabian Plate was emphasized. A lenticular rudist biostrome in the uppermost part of the Khanasir Limestone Member consists mainly of the radiolitids and sparse canaliculated rudists in life position. However, rudists are entirely fragmented in the lower limestone and are very rare in the upper limestone of the Hajajah Limestone Member. Loose right valves of radiolitids from the Campanian Khanasir Member have underwent diagenetic alterations, such as fragmentation and compaction, micritization, bioerosion, and micritic calcite cement, which indicates marine diagenetic stage, while very limited silicification, dolomitization, and dissolution suggest the meteoric diagenetic environments with arid climates. Isopachus and equant calcite cement and neomorphism may be showed the fresh pharetic zone related with subaerial unconformities.

Upper Paleocene to lower Eocene microfacies, biostratigraphy, and paleoenvironmental reconstruction in the northern Farafra Oasis, Western Desert (Egypt)

Three Paleocene-Eocene (P-E) stratigraphic transect sections namely, from the north to south, Ain Maqfi, Farafra-Ain Dalla road, and El-Quess Abu Said in the northern Farafra Oasis,Western Desert (Egypt) are described and interpreted based upon field observations, microfacies analysis, chronostratigraphy and foraminiferal paleobathymetry, to detect the effect of the Syrian Arc Fold System (SAFS) on the lateral and vertical facies changes, various stratigraphic breaks and to reconstruct the depositional paleoenvironments. Lithostratigraphically, the P-E successions are composed of the upper part of the Dakhla Formation, Tarawan Chalk and Esna Shale Formation. Vertical and lateral facies changes are noted between tectonic paleo-highs and paleo-lows in the Farafra Oasis. Eight microfacies types are recognized. The larger benthic and planktonic foraminiferal zones are here used to correlate the shallow and deeper facies. Two larger benthic (SBZ4 and SBZ6), six planktonic foraminiferal (P4–E4) and one calcareous nannofossil (NP9b) biozones are identified. The recorded basal Eocene Dababiya Quarry Member (DQM) within the Esna Shale Formation in the central Farafra Oasis is represented by units 4 and 5 of the DQMat its GSSPwith a neritic facies types. Towards the northern part of the Farafra Oasis, the P-E interval occurs within the base of the Maqfi Limestone Member that contains the larger benthic foraminiferal SBZ6 Zone and is correlated with the DQM.Amajor sea-level fall near the upper part of P5 Zone, followed by a prominent sea-level risewith a minor hiatus across the P-E interval in the Farafra Oasis reflects the complex interplay between sea level changes and tectonic signatures. Two inferred paleoenvironments, namely inner neritic and mid-outer neritic shelf have been identified.

Multi-phase dolomitization and recrystallization of Middle Triassic shallow marine–peritidal carbonates from the Mecsek Mts. (SW Hungary), as inferred from petrography, carbon, oxygen, strontium and clumped isotope data

Abstract Shallow marine to peritidal carbonates of the Triassic Csukma Formation in the Mecsek Mts. of SW Hungary are made up of dolomites, limestones and dolomitic limestones that show evidence of a complex diagenetic history. Integration of petrographic, conventional stable oxygen and carbon isotope, clumped isotope, and strontium isotope data with the paleogeography, paleoclimate, and burial history of the region revealed four major diagenetic stages. Stage 1: The peritidal carbonates were dolomitized penecontemporaneously during the Middle Triassic by refluxing evaporatively concentrated brines. Stage 2: Increasing burial during the Late Triassic–Jurassic resulted in recrystallization of the Kan Dolomite Member in an intermediate burial setting. Stage 3: During the Early Cretaceous seawater was drawn down and circulated through rift-related faults, causing renewed recrystallization of the Kan Dolomite Member as well as dolomitization of the Kozar Limestone Member and the underlying limestones in a deep burial setting, but only in the vicinity of the faults. Stage 4: During the Late Cretaceous and Cenozoic thrusting resulted in tectonic expulsion of basinal fluids and precipitation of multiple saddle dolomite cement phases near the faults. The results of this study imply that the clumped isotope method integrated with other geochemical data can successfully be applied to identify the nature and potential sources of extra-formational diagenetic fluids responsible for dolomitization and recrystallization. This study provides conclusive evidence for multi-phase dolomitization and dolomite recrystallization over several millions of years (Middle Triassic through Early Cretaceous) and several thousands of meters of burial in the Csukma Formation in SW Hungary. Furthermore, this study is the first to identify fault-controlled dolomitization by circulating Cretaceous seawater within Triassic carbonates of central Europe, further supporting the viability of the interpretation of dolomitization by seawater initially drawn down and then geothermally circulated through faults in extensional basins.

SMALL SHELLY FOSSIL PRESERVATION AND THE ROLE OF EARLY DIAGENETIC REDOX IN THE EARLY TRIASSIC

Minute fossils from a variety of different metazoan clades, collectively referred to as small shelly fossils, represent a distinctive taphonomic mode that is most commonly reported from the Cambrian Period. Lower Triassic successions of the western United States, deposited in the aftermath of the end-Permian mass extinction, provide an example of small shelly style preservation that significantly post-dates Cambrian occurrences. Glauconitized and phosphatized echinoderms and gastropods are preserved in the insoluble residues of carbonates from the Virgin Limestone Member of the Moenkopi Formation. Echinoderm plates, spines and other skeletal elements are preserved as stereomic molds; gastropods are preserved as steinkerns. All small shelly style fossils are preserved in the small size fractions of the residues (177 to 420 μm), which is consistent with the size selection of small shelly fossils in the Cambrian. Energy-dispersive X-ray spectra of individual fossils coupled with X-ray diffraction of residues confirm that the fossils are dominantly preserved by apatite and glauconite, and sometimes a combination of the two minerals. The nucleation of both of these minerals requires that pore water redox oscillated between oxic and anoxic conditions, which, in turn, implies that Lower Triassic carbonates periodically experienced oxygen depletion after deposition and during early diagenesis. Long-term oxygen depletion persisted through the Early Triassic, creating diagenetic conditions that were instrumental in the preservation of small shelly fossils in Triassic and, likely, Paleozoic examples.

Flat pebbles and their edge‐wise fabric in relation to 2‐D microbial mat

Flat pebbles and edge‐wise fabric in the Mesoproterozoic Rohtas Limestone Formation (RLF) and the Chikkshelikere Limestone Member (CLM), India, generate a new insight into their formation. Simple stacks of alternating dark micritic and light‐coloured microsparite planar layers in the targeted sedimentary successions manifest a low‐energy depositional background, disturbed only occasionally by weak storms. While the dark layers are homogeneous, light‐coloured layers are generally planar, wavy ripple laminated, and bear frequent load casts. The dark layers often display varieties of 2‐D microbial mat structures little known from carbonate formations. In compliance with their identity, they are comparatively enriched in carbon, a large part of which is organic and kerogen. The said structures with their intrinsic deformations indicate delayed cementation. Notwithstanding delayed cementation, the flat clasts in these formations are readily traceable to the dark laminae possibly because of early acquisition of their selective cohesiveness. Resultant stress led to brittle deformation in the mat layers, while the light‐coloured layers underwent ductile deformation. All the studied breccias bodies are in situ, but this fact does not preclude either the possibility of reworking of the clasts while exposed to high‐energy current or generation of intraclasts by high‐energy currents eroding the depositional surface.

First Bathonian (Middle Jurassic) nautiloid Paracenoceras Spath from Ethiopia

The earliest find of a Bathonian nautiloid Paracenoceras aff. prohexagonum Spath from the Lower Limestone Member (former Gohatsion Formation) exposed at Mugher (Blue Nile Basin, Ethiopia) is reported. Due to lack of index forms for the entire pre–Late Jurassic duration in Ethiopia, the age estimate of the nautiloid is done on the basis of palaeobiogeography where the oldest P. prohexagonum Spath record comes from definite Saudi Arabian Early Bathonian strata and the youngest from the Middle–Late Bathonian of the Kachchh basin (Western India). Ethiopia being an intermediate region, hence, a Late Bathonian age is safe to assume. However, the key for a more well–constrained age for the Ethiopian strata may actually lie in the re–assessment of the ammonite records from the neighboring Somalia, another intermediate region and a step closer to the otherwise well–constrained records from the Kachchh basin (India). Additionally, this contribution also provides a brief stratigraphic update of the Lower Limestone Member (of the Antalo Limestone Supersequence) exposed at Gohatsion and the corresponding nautiloid–bearing section at Mugher (∼20 km southwest of Gohatsion) within the Blue Nile basin. Based on field and sedimentological observations, sequence stratigraphy, and previously published data on faunal content, the prevailing paleoenvironment and relative sea level curve for the Lower Limestone Member is also inferred. Palaeobiogeography is briefly outlined to explain the age and occurrence of the reported nautiloid.

Solitary corals of the Campanian Hajajah Limestone Member, Aruma Formation, Central Saudi Arabia

Fourteen species of the solitary corals belonging to eight genera and six families were identified and illustrated from the Campanian – Maastrichtian Aruma Formation, northeast of Riyadh, Saudi Arabia. Cunnolites (Plesiocunnolites) riyadhensis, Actinoseris riyadhensis and Asteroseris arabica are believed to be new. Genus Cunnolites dominates the identified fauna with six species namely Cunnolites (C.) reussi, C. (P.) orbignyi, C. (P.) longifossata, C. (P.) scutellum, C. (C.) profundus and C. (P.) riyadhensis (n. sp.). The other species belong to Aulosmilia cuneiformis, Rennensismilia inflexa, Rennensismilia sp., Acrosmilia conica, Actinoseris riyadhensis (n. sp.), Asteroseris arabica (n. sp.), Montlivaltia sp. and Conicosmilotrochus sp. The solitary corals have various growthforms from cupolate to flabellate, trochoid, ceratoid, cylindrical and patellate. The studied taxa inhabit soft substrate in turbid water environment with low rate of sedimentation. Borings and scars are rare, encrustations occur on the lower surfaces of some specimens. Partial mortality, overgrowths, disorientation or any records of life impedences due to sedimentation and unstable substrate were not observed in the studied specimens. Pedestals and columnar growths are also absent. Bioerosion is observed in some specimens in the form of pittings produced by predators.

A New Fossil Vertebrate Locality of the Jetmore Chalk Member of the Upper Cretaceous Greenhorn Limestone in North-Central Kansas, U.S.A.

The Jetmore Chalk Member of the Greenhorn Limestone is a Late Cretaceous rock unit deposited under the Western Interior Seaway in North America. We here report an assemblage of vertebrate fossils collected through surface collecting and bulk sampling at a new Jetmore Chalk locality in Republic County, Kansas, U.S.A. Taxonomically, it consists of diverse carnivorous fish taxa (e.g., Ptychodus, Cretoxyrhina, Squalicorax, Pachyrhizodus, and Plethodidae), indicating that the marine paleoecology during the deposition of the Jetmore Chalk was quite complex. The fossil assemblage also includes the first record of the aquatic lizard, Coniasaurus cf. C. crassidens, from the Jetmore Chalk, as well as the first record of a ‘billfish’-type bony fish, Cylindracanthus sp., from Kansas that also represents the oldest fossil record for the genus. Whereas the overall taxonomic composition of known fossil vertebrates from the Jetmore Chalk is consistent with typical Cenomanian-Santonian vertebrate assemblages of the Western Interior Seaway, this study demonstrates the presence of local differences in the relative abundance of fossils across different fish taxa between a known Jetmore Chalk locality and the new Jetmore Chalk locality described in this study.

Larger foraminifera of the Devil's Den and Blue Hole sinkholes, Florida

Abstract. Shallow-water carbonate deposits are well-known from the Eocene of the US Gulf Coast and Caribbean. These deposits frequently contain abundant larger benthic foraminifera (LBF). However, whilst integrated stratigraphic studies have helped to refine the timing of LBF overturning events within the Tethys and Indo-Pacific regions with respect to global bio- and chemo-stratigraphic records, little recent work has been carried out in the Americas. The American LBF assemblages are distinctly different from those of Europe and the Indo-Pacific. It is therefore essential that the American bio-province is included in studies of LBF evolution, biodiversity and climate events to understand these processes on a global scale. Here we present the LBF ranges from two previously unpublished sections spanning 35 and 29 m of the upper Eocene Ocala limestone, as the early stages of a larger project addressing the taxonomy and biostratigraphy of the LBF of Florida. The study indicates that the lower member of the Ocala limestone may be Bartonian rather than Priabonian in age, with implications for the biostratigraphy of the region. In addition, the study highlights the need for multiple sites to assess the LBF assemblages and fully constrain ranges across Florida and the US Gulf and suggests potential LBF events for future integrated stratigraphic study.

A geohistorical retrospective analysis of cultural heritage buildings: the case of Mosta Dome, Malta

Geohistorical retrospective analysis attempts to establish the location of industrial mineral extractive sites. This paper is based on a study of the Rotunda of Mosta, a feat in architectural engineering structures inspired by the Pantheon in Rome. It was designed and erected in local Lower Globigerina Limestone. This Neoclassical church is the third largest unsupported masonry dome in the ecclesiastical architectural history of Europe. According to oral tradition, the architect Giorgio Grognet de Vasse had opted to use limestone from Ta’ Vnezja in the limits of Mosta. A retrospective analysis of the geological fabric used in the construction of the church proves that the limestone was not from this area but from a locality in its close proximity, namely Ta’ Qali. Although the geology present at both sites was considered similar at the time of erecting the church and the respective relative suitability for use as dimension stone was known, the limestone at Ta’ Vnezja is lithologically different from Ta’ Qali. At both these localities quarries were sunk in their lithostratigraphic sub-formation namely the Middle Globigerina Limestone Member and the Lower Globigerina Limestone Member respectively.

Devonian–Carboniferous brachiopods and biostratigraphic findings from the Kangal Phyllite–Slate Formation (greenschist), Sivas, Turkey

The Kangal Phyllite-Slate Formation forms the basement rocks in Kangal-Çetinkaya-Alacahan-Divriği (Sivas). These late Paleozoic phyllite-slate associations occupy a large area, possibly composed of Early Paleozoic sediments in its lower part. The lower levels (Bakırtepe Metaquartzite Member; 0-500 m) and uppermost levels comprise the Düzce Recrystallized Limestone Member (0-25 m). The lower boundary is invisible and the upper boundary is unconformably overlain by the Kıratgediği Limestone (late Jurassic- early Cretaceous). The studied brachiopod fauna, about 400 specimens, was collected from the 150-m-thick uppermost part of the greenschist sequences in the Kulluk Hill area, Elkondu village, 25 km east of Kangal. Some bryozoans, corals, trilobites, and crinoids were also retrieved. Five fossiliferous levels belonging to the lower, middle, and upper Devonian, and the lower Carboniferous stages were assigned as follows: (1) Pragian-Emsian; (2) Eifelian-Givetian; (3) Fransian-Famennian-Etroeungtian (Strunian); the Devonian- Carboniferus boundary; (4) lower Carboniferus: Tournaisian and Viséan stages, based on the brachiopods; and (5) upper Permian: from Roadian to Capitanian stages, based on the foraminifera and algae in the Düzce recrystallized limestone. This level indicates a sedimentary interruption. All of these fossils and fossiliferous beds were correlated with the type localities and related beds. The Kangal brachiopods are similar to those of Şafaktepe, the Gümüşali Formations (middle and upper Devonian), and the Ziyarettepe Formation (lower Carboniferous) of the eastern Taurides. The brachiopod community is closely affiliated with the Mediterranean, northwest European Faunal Provinces, part of the Transcaucasian Region, and microfossils of the Düzce recrystallized limestone belonging to the Tethyan Region. Brachiopod fauna and lithologic characteristics of the formation suggest that the upper (150 m) greenschist sequences were deposited in an open shelf environment under warm sea conditions in the Late Paleozoic era.

Nummulitids, lepidocyclinids and Sr-isotope data from the Oligocene of Kutch (western India) with chronostratigraphic and paleobiogeographic evaluations

Due to its intermediate geographical position between the Mediterranean and W Pacific, the Oligocene shallow-marine sequence of Kutch (India) is of key importance in paleobiogeographical interpretations. Larger benthic foraminifera (LBF) are a fundamental link for the correlation between the Mediterranean shallow benthic zones (SBZ) and the W Pacific ‘letter stages’. LBF were re-evaluated by morphometric studies of the internal test from five stratigraphic sections of the Maniyara Fort Formation. Based on their significant affinity to coeval fauna in the Mediterranean, they were assigned to W Tethyan SBZ zones, supported by Sr-isotope stratigraphy. In the Basal Member, traditionally considered as early Rupelian, we identified Nummulites bormidiensis, N. kecskemetii and Heterostegina assilinoides assigning it to the early Chattian SBZ 22B Zone. The Coral Limestone Member, previously considered as late Rupelian, is also assigned to this zone, for the presence of N. bormidiensis, Eulepidina formosoides-dilatata and Nephrolepidina morgani-praemarginata. Its early Chattian age (26.5–29 Ma) is further supported by Sr-isotope data. Miogypsinoides complanatus and Spiroclypeus margaritatus in the Bermoti Member (the top of the formation) document the late Chattian SBZ 23 Zone and the Sr-isotope data (22.5–24 Ma) place it close to the Oligocene–Miocene boundary.

Chemostratigraphic and depositional characterization of the Niobrara Formation: Techniques for assessing lateral heterogeneity, CEMEX Quarry, Lyons, Colorado, Denver-Julesburg Basin

The Late Cretaceous (89–82 Ma) Niobrara Formation is the primary target for unconventional horizontal well activity in the Denver Basin. With an abundance of horizontal activity, the question of well-length scale lateral heterogeneity becomes paramount addressing steering practices, completion, and ultimately well performance. We have incorporated detailed core description, high-resolution chemostratigraphy, and petrophysical logs from four near-surface cores taken at the CEMEX Lyons Quarry to assess lateral heterogeneity. Cores were originally intended to determine the geochemistry and areal extent of the Fort Hays Limestone Member of the Niobrara Formation, CEMEX’s primary target for cement production. However, due to the cores’ proximity to one another (91.4–609.6 m [300–2000 ft]) and the presence of not only the Fort Hays Limestone but also the petroliferous chalks and marls of the Lower Smoky Hill Member (including the D Chalk, C Marl, and a portion of the C Chalk), the data set can also be used as a proxy to model changes along a pseudohorizontal wellbore. Observations include lateral bentonite discontinuity, trace element and organic carbon variations, and distinct changes in sedimentary structures. Well-length sedimentological and stratigraphic changes may have unique implications for unconventional oil and gas development.

Trace fossils of an amalgamated storm-bed succession from the Jurassic of the Kachchh Basin, India: The significance of time-averaging in ichnology

The uppermost part of the Upper Bathonian Sponge Limestone member, Patcham Formation, of the Jhura Dome of Kachchh Mainland is a thickening- and shallowing-upward succession topped by medium- to thick-bedded hummocky cross-stratified grainstones deposited by storm waves. Occasionally, thin, commonly lenticular, intraclastic–bioclastic silty marl intercalations between the grainstones are highly bioturbated, in contrast to the grainstones, in which, for the most part, trace fossils occur scattered. Large exposures of bedding planes of the grainstones allow the detailed investigation of ichnological features, whereas the high density of traces in the soft marls precludes the identification of any ichnotaxa. Eighteen ichnotaxa have been recorded including Ophiomorpha, Thalassinoides, Taenidium, Gyrophyllites, Chondrites, Dactyloidites, Teichichnus, Bolonia, and Ancorichnus. Except for Ophiomorpha nodosa and Thalassinoides, which generally indicate moderate to high energy conditions and are the dwelling burrows of suspension-feeding to omnivorous crustaceans, the ichnotaxa represent a deposit-feeding behaviour of their producers and thus are characteristic of low-energy environments. The trace fossils form three ichnoassemblages characterized by (1) Ophiomorpha nodosa and Thalassinoides suevicus, (2) ?Thalassinoides isp. A, Taenidium, and Bolonia lata, and (3) Ancorichnus. The dominance of traces of deposit-feeders in rocks indicative of high-energy events is counterintuitive and points to their non-contemporaneity. The sediments were deposited during brief high-energy events, whereas the trace fossils were produced when, after waning of storms low-energy conditions prevailed. This time-averaging is particularly pronounced in trace fossils that extend vertically downwards and may reach strata deposited under distinctly different conditions. Thus, environmental interpretations based on trace fossils should refer to colonisation surfaces rather than to the sediment surrounding the trace fossils. In the latter case, interpretations may be erroneous, especially when erosion subsequently destroyed sedimentary evidence of their original environment.

Dinocyst stratigraphy and palaeoenvironmental interpretation of the Cretaceous/Paleogene boundary at Stevns Klint, Denmark

A re-examination of the uppermost Maastrichtian chalks and an expanded section of the Fish Clay (Fiskeler Member) undertaken at Stevns Klint, Denmark, one of the classic outcrops of the Cretaceous/Paleogene boundary, has identified diverse and abundant dinoflagellate cyst assemblages, which are compared with earlier dinoflagellate cyst (dinocyst) studies. The uppermost part of the white coccolith chalk (Sigerslev Member) of the uppermost Maastrichtian is placed in the Palynodinium grallator Zone. The overlying ‘Grey Chalk’ (Højerup Member) represents a shallower-water marine succession that is characterised by a series of dune-like structures. The last common occurrence of P. grallator is within the Højerup Member, confirming the Danian age for the Fish Clay (Fiskeler Member) and a latest Maastrichtian age for the P. grallator Zone. Within the Fiskeler Member, Damassadinium californicum (previously known as Danea californica), a key biostratigraphical marker, is only intermittently present, while the distributions of Senoniasphaera inornata and Xenicodinium reticulatum provide useful biostratigraphic control. The well-preserved dinocysts of the Fiskeler Member are replaced by reduced assemblages in the Cerithium Limestone Member with only pollen grains recorded.

THE GEOLOGICAL EVOLUTION OF SORGUN (YOZGAT)-YILDIZELİ (SİVAS) FORELAND BASIN, PETROGRAPHIC, GEOCHEMICAL ASPECTS AND GEOCHRONOLOGY OF VOLCANISM AFFECTING THE BASIN

Sorgun-Yıldızeli basin is an east-west trending asymmetric marginal foreland (peripheral foreland basin) formed as a result of the consumption of oceanic crust of the northern branch of Neotethys due to the collision of Sakarya continent in the north and Kırşehir Block in the south. It provides much information about the geodynamic evolution of the region. The basement of the study area consists of Late Palaeozoic-Mesozoic Akdağmadeni Massif. Akdağmadeni Massif was intruded by CenomanianMaastrichtian granitoids and is overlain tectonically by Late Cretaceous Artova ophiolitic melange within the İzmir-Ankara-Erzincan suture zone and by Cenomanian-Maastrichtian Darmik Formation. The volcano-sedimentary sequence deposited in Sorgun-Yıldızeli foreland basin developed on the relicts of the İzmir-Ankara-Erzincan Suture Zone along the northern margin of Kırşehir Block and was named the Boğazköy Formation. The pelitic, clastic and coarse clastic levels of Upper Palaeocene-Middle Eocene Boğazköy Formation including İzmir-Ankara-Erzincan Suture Zone slices and olistostromes are differentiated as the Dolak member. Toward the inner part of the basin, a turbiditic sequence of conglomerate, sandstone, claystone including rare limestone beds was deposited, consisting of conglomerate, sandstone, claystone, rarely limestone and alternations of three different volcanic rocks (acidic, basic and intermediate) related to subduction and/or collision. Calc-alkaline lava and pyroclastics of basaltic and basalt-andesite composition were differentiated as the Pazarcık volcanic member, with lava and pyroclastics of dacitic and rhyolitic composition called the Sarayözü volcanic member and calcalkaline lava and pyroclastics of andesitic, trachyandesitic and dacitic composition called Kiremitlik volcanic member in Sorgun-Yıldızeli basin. According to the 40Ar/39Ar geochronologic method, the ages of 57.2±2.0 Ma and 56.7±1.8 Ma were obtained for Pazarcık volcanics, 48.8±1.5 Ma for Sarayözü volcanics and 45.1±1.3 Ma and 47.3±0.6 Ma for Kiremitlik volcanics. The reefal limestones which are not thick and occur in higher parts of the Boğazköy Formation were called the Limestone member. The uppermost section of the sequence which consists of generally clastic and coarse clastics is named the Konacı member. When the sedimentation and volcanism continued in the basin, gabbroic intrusions occurred as sills and laccoliths cutting the Boğazköy Formation. These gabbroic rocks were named the Yaycılar Gabbro. The age of 51.0 ± 0.7 Ma was found for the Yaycılar Gabbro with the 40Ar/39Ar geochronologic method. As a result of slab breakoff, the relicts of the consumed oceanic crust and the released massif were uplifted rapidly and the units of Middle-Late Eocene Tokuş Formation were deposited transgressively on the Boğazköy Formation and on outcropping basement rocks in the basin which was controlled by an extensional tectonic regime. Upper Miocene-Pliocene (İncesu Formation), Pliocene and Quaternary terrestrial sediments were deposited unconformably on all older units.

After the disaster: Bony fish remains (mostly otoliths) from the K/Pg boundary section at Stevns Klint, Denmark, reveal consistency with teleost faunas from later Danian and Selandian strata.

This is the first study of bony fish remains across the K/Pg boundary section at Stevns Klint, Denmark. The studied specimens comprise one partly preserved articulated skeleton, a few isolated bones, and casts from several otolith imprints and voids. As otoliths are aragonitic, the remains are all dissolved. The imprints of the otoliths originate from the uppermost Maastrichtian Højerup Member or ‘Grey Chalk’, and the bone fragments and the partial skeleton were obtained from the Fiskeler Member directly above the K/Pg boundary. Further otolith imprints originated from the basal Danian Cerithium Limestone Member, which directly overlies the Fiskeler Member. Six otolith-based taxa were identified from the uppermost Maastrichtian and three from the basal Danian. One of the species found in the uppermost Maastrichtian persisted into Danian times (Polymixia? harderi), a second represents a common genus in both Maastrichtian and Danian but cannot be identified to the species level (Centroberyx sp.), and a third taxon is an unidentifiable dynematichthyid, which, however, certainly does not belong to any of the known Danian dinematichthyid species. The species recognised in the basal Danian all persisted well into later Danian times or even the Selandian, showing a remarkable consistency of the early Paleocene bony fish fauna. We find no indication of phased extinction in the aftermath of the K/Pg boundary event in the data recovered from the Danian.

Application of palynology and petrography in the correlation of the Pennsylvanian Brazil and Staunton Formation coals in the eastern part of the Illinois Basin

The coals of the Brazil and the lower part of the Staunton Formations (Atokan and early Desmoinesian, Pennsylvanian) in Indiana (Illinois Basin) are typically thin and discontinuous. As a result, both researchers and the industry have experienced problems with coal bed identification and correlation. The discrepancies in coal nomenclature and frequent miscorrelations affect coal exploration, mine planning, and communication between mines and customers. Our previous study, based on exploration boreholes, mine-scale observations, and coal quality and petrographic data from Daviess, Greene, and Clay Counties, Indiana, suggested that the coal mapped as the Upper Block Coal Member of Clay County might be the same seam as the Lower Block Coal Member of Daviess County. This study is an extension of the previous research conducted farther south to Pike, Warrick, and Spencer Counties, Indiana. In the southern part of Indiana, correlation of these late Atokan and early Desmoinesian coal beds is even more difficult because of the absence of well-defined marker horizons and limited mining and subsurface well data. Although palynological and coal petrography data generally correspond, these data alone cannot resolve the correlation of the coal beds in this southern region with the coals of Clay or Greene Counties, and they must be supplemented with the analysis of associated limestones. The ability to accurately identify the Perth Limestone Member, which occurs close to the Buffaloville Coal Member of the Brazil Formation, and the Holland Limestone Member, which occurs higher up in the Staunton Formation, will help to distinguish between Brazil and Staunton Formation coals.

Natural Casts of Early Eocene Entobia from the Kachchh Basin, India

ABSTRACTExcellently preserved natural casts of sponge borings Entobia Bronn from the Early Eocene rocks of the Kachchh basin, India are reported for the first time. The entobian bioerosion is represented by four ichnospecies viz., Entobia cateniformis, E. geometrica, E. ovula, and E. paradoxa. Molds and casts of bivalves belonging to family Carditidae served as substrate for these sponge borings. The relation between mode of preservation of the natural casts, sea water chemistry, and time of emplacement of borings is discussed. The bored bioclasts are associated with Schaubcylindrichnus, Thalassinoides, and Rhizocorallium. This study indicates that the sediments of Assilina Limestone Member were deposited in turbidity-free, shallow water with nil or low rates of sedimentation.