Dating sedimentary carbonates using the U-Pb method can help improve the Phanerozoic timescale. Using a novel combination of laser-ablation, multi-collector, inductively-coupled-plasma, ...mass-spectrometry (LA–MC–ICP–MS) and thermal ionization multi-collector mass spectrometry (TIMS), U-Pb numerical ages were obtained on early-diagenetic calcite cements in Jurassic ammonites in which concentrations of U range from 0.47 to 5.3ppm.
The calcite cements of two ammonites, IS1 and IS2, from the uppermost Bifrons Zone of the Toarcian (179–180Ma) of the UK, gave TIMS-normalized LA U–Pb dates of 164.9±5.3Ma and 166.7±4.8Ma respectively. Normalizing LA–ICP–MC–MS data to an in-house calcite standard gave a more precise date of 165.5±3.3Ma for IS1 cement. An unzoned ammonite, SS2, of Bajocian age (168–170Ma) yield a TIMS-normalized LA U–Pb age of 158.8±4.3Ma for its early-diagenetic cement. Both the combined LA–MC–ICP–MS and TIMS approach, and the use of a calcite laser ablation standard can result in accurate ages of cements with uncertainties of 2–3% (2σ). The later, however, is more efficient and precise. These U-Pb dates of cements are 10 to 20Myr younger than the numerical ages of the biostratigraphic intervals from which the ammonites derive. The U-Pb dates are taken to represent the time at which the aragonite shell of the ammonite inverted to calcite and released its U to precipitate in a late-diagenetic alteration of early-diagenetic fringing cements.
Concentrations of U and Pb in a range of other pristine biogenic carbonates were found too low (U<0.01ppm) for meaningful dating using laser ablation method.
•Primary biogenic calcite contains <0.01ppm of U, so it is unfeasible for U–Pb dating.•Common Pb anchored TIMS U–Pb data yield U–Pb dates for diagenetic calcite cements.•TIMS-normalized LA U–Pb data give precise U–Pb dates for the diagenetic calcite.•Calcite standard normalized LA U–Pb data give the best U–Pb dates for the cements.•Ammonite cement U–Pb ages record the time of aragonite inversion to calcite.
The rock successions of the Chia Gara Formation were studied at two surface sections (Barsarin and Rania) from North-Eastern Iraq. The detailed sedimentological study reveals that the formation ...consists basically of thin-bedded black limestone, dolomitic limestone, marly limestone, bituminous shales, and Ammonitic limestone. The petrography results showed that the formation consists of various petrographic components as Ammonites, calcispheres, radiolarian, and silicate sponges in addition to the groundmass of micrite. Ammonite taxa are examined in the upper part of the Chia Gara Formation to find Ammonite species, of which seven species have been identified. One biozone is postulated based on the above assemblages, in order of age: Berriasella Jacobi, from a regional perspective, this biozone was connected with other Ammonite assemblages, leading to the conclusion that the Formation age is Early Cretaceous in age. The facies analysis demonstrates that the rock succession consists mainly of three microfacies. The main microfacies include lime mudstone, wackestone, and packstone. At the same time, the lithofacies comprise limestones and shales. The overall characteristics of these facies show that the Chia Gara Formation was deposited in three different environments; (1) the Lower part of the Upper bathyal (2) the Middle part of the bathyal, and (3) the Upper part of the outer shelf environment.
An ammonite trapped in Burmese amber Yu, Tingting; Kelly, Richard; Mu, Lin ...
Proceedings of the National Academy of Sciences - PNAS,
06/2019, Letnik:
116, Številka:
23
Journal Article
Recenzirano
Odprti dostop
Amber is fossilized tree resin, and inclusions usually comprise terrestrial and, rarely, aquatic organisms. Marine fossils are extremely rare in Cretaceous and Cenozoic ambers. Here, we report a ...record of an ammonite with marine gastropods, intertidal isopods, and diverse terrestrial arthropods as syninclusions in mid-Cretaceous Burmese amber. We used X-ray–microcomputed tomography (CT) to obtain high-resolution 3D images of the ammonite, including its sutures, which are diagnostically important for ammonites. The ammonite is a juvenile Puzosia (Bhimaites) and provides supporting evidence for a Late Albian–Early Cenomanian age of the amber. There is a diverse assemblage (at least 40 individuals) of arthropods in this amber sample from both terrestrial and marine habitats, including Isopoda, Acari (mites), Araneae (spiders), Diplopoda (millipedes), and representatives of the insect orders Blattodea (cockroaches), Coleoptera (beetles), Diptera (true flies), and Hymenoptera (wasps). The incomplete preservation and lack of soft body of the ammonite and marine gastropods suggest that they were dead and underwent abrasion on the seashore before entombment. It is most likely that the resin fell to the beach from coastal trees, picking up terrestrial arthropods and beach shells and, exceptionally, surviving the high-energy beach environment to be preserved as amber. Our findings not only represent a record of an ammonite in amber but also provide insights into the taphonomy of amber and the paleoecology of Cretaceous amber forests.
A newly discovered ammonite of the genus Hyperlioceras from the Lincolnshire Limestone Formation of Eastern England enables the biostratigraphical position of the principal building stone of Lincoln ...Cathedral: the ‘Silver Bed’ variant of Lincoln Stone (Lower Lincolnshire Limestone) to be precisely dated as subsectum biohorizon of the Lower Bajocian, Discites Zone. Ammonites are extremely rare in this formation thus the impetus to record it here and provide a firm date for strata in which it occurred following its discovery. The lithostratigraphical provenance of the specimen is briefly discussed and evidence provided to support the conclusion.
The ammonite record of two stratigraphic sections, La Boca Canyon and La Huasteca Canyon, of the La Peña Formation in Nuevo León State, northeast Mexico, was studied in this work. In Mexico, ammonite ...provincialism during the Aptian prevents the use of European zonations. We followed previous works where we proposed the critical need to define an independent ammonite zonation for the Central Atlantic Province. The current study constitutes an advance in the development of an Aptian ammonite zonation for Mexico. The methodology employed is the usual in this kind of contribution, but two additional methodologies must be highlighted, a semi-quantitative biostratigraphy and the use of 3D models in showing the more relevant specimens. These methodologies are not new, but are uncommon in the contributions of the majority of the Lower Cretaceous ammonite workers, and can be an interesting example to follow. Three ammonite zones and one subzone were recognized: Dufrenoyia justinae interval Zone, Caseyella aguilerae interval Zone, Kazanskyella minima interval Zone and Dufrenoyia scotti/Burckhardtites nazasensis concurrent range Subzone. In addition, taxonomic contributions in some species of the genera Cheloniceras, Epicheloniceras and Kazanskyella have been made. The lower/upper Aptian transition in Mexico and Europe is discussed. Several options of study have been proposed in order to better characterize the lower/upper Aptian transition in Europe and its correlation with Mexico. This work aims at stabilizing the Mexican zonation and its applicability/reproducibility for the whole Central Atlantic Province.
The ammonite assemblage of the planula Biohorizon (Early Kimmeridgian, Planula Zone) is studied in detail, mainly based on bed-by-bed collected specimens from the Wohlgeschichtete-Kalke Formation of ...the Plettenberg Quarry near Balingen (western Swabian Alb) and some additional specimens from coeval beds of the former Schneider Quarry at Spielberg am Hahnenkamm (southwestern Franconian Alb). Within the Upper Jurassic of Southern Germany, the planula Biohorizon is one of the few well-characterized biohorizons of the Lower Kimmeridgian. Its ammonite assemblage comprises at least 16 ammonite taxa, most of which are typical of the Submediterranean or Mediterranean provinces; only few of them are of Subboreal affinity, whereas Boreal taxa are completely absent.
Hantken Miksa pályája elején az ammoniteszekről kora geológusainak átlagos ismereteivel bírt. Elsőként gyűjtött bakonyi jura ammoniteszeit még Bécsbe vitte meghatározásra. Terepi munkálkodásai során ...– elemi mikropaleontológiai érdeklődése mellett – egyre jobban kezdték érdekelni az ammoniteszek, amit gyűjtései jeleznek. Tekintélyes ammonitesz-anyagot halmozott fel a Gerecséből, a Bakonyból, de távolabbi lelőhelyekről, például Villányból és az al-dunai Swinitzáról, de külföldről is. Bár ammoniteszekről csupán egyetlen rövid dolgozata jelent meg, ez azonban tartalmazza azt a felismerést, hogy a bakonycsernyei ammoniteszek tekintélyes része a Mediterrán jura területén az akkor alig ismert aaleni – kora bajóci faunát képviseli. Nekilátott az anyag feldolgozásának. Huszonöt kőnyomatos táblát készíttetett, az ammoniteszek egy részéről jegyzeteket, leírásokat, összehasonlításokat írt, új fajokat nevezett el. Sajnos a munkát egyetemi elfoglaltságai, majd hirtelen halála miatt nem fejezhette be. Gazdag gyűjteményei viszont alapját képezték a magyarországi jura ammoniteszekről írott három legfontosabb, a szakirodalom által is kiemelkedő jelentőségűnek tartott munkának: Prinz Gyula (1906) és Géczy Barnabás (1966-67) csernyei, és ifj. Lóczy Lajos (1915) villányi monográfiájának. Bakonycsernyei ammoniteszekről és mikrofauna elemekről a legutóbbi időkben is közzétett publikációk azt mutatják, hogy az Őslénytani Tanszéken elevenen él a tanszék alapítója teremtette hagyomány.
The Kopet Dagh sedimentary basin is situated in the northeast of Iran and the south of Turkmenistan. The present work focuses on the systematic representative's species of the Family Phylloceratidae ...Zittel, 1884, of the Family Gaudryceratidae Spath 1927, of the Family Oppeliidae H. Douvillé, 1890, and of the Family Desmoceratidae Zittel, 1895, all of which are for the first time in the basin. Based on previous studies and assemblage fauna in this study, a late Barremian-early Aptian age is suggested for the measured sequences. The palaeobiogeographical distribution of the ammonites indicates that during the late Barremian to the late Aptian the basin formed part of the Tethyan realm, Mediterranean-Himalayan Province. The studied fauna and other reported ammonites in previous publication might suggest nearshore to offshore an epipelagic to pelagic environment. There is also a relation between the lithology and the morphotype of ammonites.
Le bassin sédimentaire de Kopet Dagh est situé au nord-est de l’Iran et au sud du Turkménistan. Le présent article se concentre sur les espèces représentatives des familles des Phylloceratidae Zittel, 1884, des Gaudryceratidae Spath 1927, des Oppeliidae H. Douvillé, 1890, et des Desmoceratidae Zittel, 1895 qui sont toutes nouvelles dans le bassin. Sur la base de la faune de l’assemblage étudié et d’études antérieures, un âge Barrémien final-Aptien basal est proposé pour les séquences étudiées. Les relations paléobiogéographiques des ammonites indiquent que, du Barrémien supérieur à l’Aptien supérieur, le bassin faisait partie du domaine téthysien, province méditerranéenne-himalayenne. La faune de l’assemblage étudié, ainsi que d’autres faunes d’ammonites signalées, suggèrent un environnement épipélagique à pélagique côtier à extracôtier. Il existe également une relation entre la lithologie et le morphotype des ammonites.
In the Zagros Basin (southwestern Iran), a 270 m thick section of shales, marls, marly limestones and limestones of the Kazhdumi Formation has yielded a diverse ammonite fauna which allowed for a ...detailed biostratigraphic zonation. Aptian ammonites of the families Deshayesitidae and Parahoplitidae occur indicating a latest early to late Aptian age. Albian Douvilleiceratidae, Lyelliceratidae and Brancoceratidae indicate early, middle and late Albian age. Their range and generic and specific determinations are tabulated and illustrated.
We report the discovery of a Late Cretaceous ammonite, Pseudokossmaticeras brandti, in an archaeological context at Cueva Tres Bocas de Tanteo, located near the town of Rodas, Cienfuegos Province, in ...south-central Cuba. The ammonite manuport is much older than the middle Eocene limestone rock on the cave site and, thus, was likely transported from one of the nearby Upper Cretaceous deposits that outcrop several kilometers away. The ammonite specimen presents a broken umbilicus with the margins of the opening slightly modified. This is the first record of Pseudokossmaticeras brandti in Cuba, and along with another two partial specimens from Costa Rica, it further extends the range distribution of this taxon in the Caribbean province during the Late Cretaceous.
•We report the presence of a human-modified kossmaticeratid ammonite found in a pre-Columbian archaeological context in central Cuba.•This is the first record of Pseudokossmaticeras brandti in Cuba.•The presence of this ammonite in an archaeological context suggests that it was a manuport.
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