Toarcian (Late Early Jurassic) to Aalenian (Early Middle Jurassic) Radiolarian Fossils from a Chert Outcrop in Marcilla, Eastern Busuanga Island

Jurassic sedimentary rocks of southern to central Quesnellia record the history of the Quesnellian magmatic arc and reflect increasing continental influence throughout the Jurassic history of the terrane. Standard petrographic point counts, geochemistry, SmNd isotopes and detrital zircon geochronology, were employed to study provenance of rocks obtained from three areas of the terrane. Lower Jurassic sedimentary rocks, classified by inferred proximity to their source areas as proximal or proximal basin are derived from an arc source area. Sandstones of this age are immature. The rocks are geochemically and isotopically primitive. Detrital zircon populations, based on a limited number of analyses, have homogeneous Late Triassic or Early Jurassic ages, reflecting local derivation from Quesnellian arc sources. Middle Jurassic proximal and proximal basin sedimentary rocks show a trend toward more evolved mature sediments and evolved geochemical characteristics. The sandstones show a change to more mature grain components when compared with Lower Jurassic sedimentary rocks. There is a decrease in εNdT values of the sedimentary rocks and Proterozoic detrital zircon grains are present. This change is probably due to a combination of two factors: (1) pre-Middle Jurassic erosion of the Late Triassic Early Jurassic arc of Quesnellia, making it a less dominant source, and (2) the increase in importance of the eastern parts of Quesnellia and the pericratonic terranes, such as Kootenay Terrane, both with characteristically more evolved isotopic values. Basin shale environments throughout the Jurassic show continental influence that is reflected in the evolved geochemistry and SmNd isotopes of the sedimentary rocks. The data suggest southern Quesnellia received material from the North American continent throughout the Jurassic but that this continental influence was diluted by proximal arc sources in the rocks of proximal derivation. The presence of continent-derived material in the distal sedimentary rocks of this study suggests that southern Quesnellia is comparable to known pericratonic terranes.

Download Full-text

Mesozoic Intracontinental Orogeny in the Tectonic History of the Kolyvan’– Tomsk Folded Zone (Southern Siberia): a Synthesis of Geological Data and results of Apatite Fission Track Analysis

Russian Geology and Geophysics ◽

10.2113/rgg20204172 ◽

2021 ◽

Vol 62 (9) ◽

pp. 1006-1020

Author(s):

F.I. Zhimulev ◽

E.V. Vetrov ◽

I.S. Novikov ◽

G. Van Ranst ◽

S. Nachtergaele ◽

...

Keyword(s):

Early Cretaceous ◽

Middle Jurassic ◽

Late Jurassic ◽

Fission Track ◽

Early Jurassic ◽

Late Triassic ◽

Apatite Fission Track ◽

History Of ◽

Paleozoic Rocks ◽

Orogenic Events

Abstract —The Kolyvan’–Tomsk folded zone (KTFZ) is a late Permian collisional orogen in the northwestern section of the Central Asian Orogenic Belt. The Mesozoic history of the KTFZ area includes Late Triassic–Early Jurassic and Late Jurassic–Early Cretaceous orogenic events. The earlier event produced narrow deep half-ramp basins filled with Early–Middle Jurassic molasse south of the KTFZ, and the later activity rejuvenated the Tomsk thrust fault, whereby the KTFZ Paleozoic rocks were thrust over the Early–Middle Jurassic basin sediments. The Mesozoic orogenic events induced erosion and the ensuing exposure of granitoids (Barlak complex) that were emplaced in a within-plate context after the Permian collisional orogeny. Both events were most likely associated with ocean closure, i.e., the Paleothetys Ocean in the Late Triassic–Early Jurassic and the Mongol–Okhotsk Ocean in the Late Jurassic–Early Cretaceous. The apatite fission track (AFT) ages of granitoids from the Ob’ complex in the KTFZ range between ~120 and 100 Ma (the Aptian and the Albian). The rocks with Early Cretaceous AFT ages were exhumed as a result of denudation and peneplanation of the Early Cretaceous orogeny, which produced a vast Late Cretaceous–Paleogene planation surface. The tectonic pattern of the two orogenic events, although being different in details, generally inherited the late Paleozoic primary collisional structure of the Kolyvan’–Tomsk zone.

Download Full-text

TRIASSIC-JURASSIC DEPOSITIONAL HISTORY OF THE DAMPIER AND BEAGLE SUB-BASINS, NORTHWEST SHELF OF AUSTRALIA

The APPEA Journal ◽

10.1071/aj79003 ◽

1980 ◽

Vol 20 (1) ◽

pp. 25

Author(s):

A. Crostella ◽

T. Barter

Keyword(s):

Middle Jurassic ◽

Early Jurassic ◽

Late Triassic ◽

Depositional History ◽

Reservoir Rocks ◽

Potential Source ◽

Regional Tectonic ◽

History Of ◽

Extensional Faulting ◽

Coastal Sedimentation

Very large gas accumulations were discovered in the Dampier Sub-basin on the Northwest Shelf of Australia during the early 1970's. The majority of the reservoirs are fluvial and marginal marine sandstones within a thick intra-cratonic clastic sequence of Early Triassic to Middle Jurassic age. Parts of this succession have been penetrated by more than 60 wells within the Dampier Sub-basin and the adjacent Beagle and Barrow Sub-basins.Broad regional palaeoenvironmental episodes have been established using oriented core supplemented by seismic, palaeontologic and wireline log data. The earliest episode was an Early to Middle Triassic transgressive-regressive cycle which led to marine and marginal marine deposition, followed during the Middle to Late Triassic by dominantly fluvial deposition. A transgression began in the early Rhaetian, characterised by deltaic, estuarine, lagoonal and coastal sedimentation which gave way to fully marine conditions during the Early Jurassic (Hettangian); this was followed by a regressive cycle.A regional tectonic episode followed which resulted in development of troughs, and brought about associated extensional faulting. Marine conditions which typified the Early Jurassic (Sinemurian) persisted until the beginning of the Middle Jurassic (Bajocian) in the Dampier Sub-basin, but passed rapidly to a fluvio-deltaic cycle in the Beagle Sub-basin. Regressive conditions extended gradually westward until sedimentation was interrupted by the onset of major continental break-up toward the end of the Middle Jurassic.The deposition of an alternating sequence of thick shale and sand during mainly restricted marine and continental conditions has provided the area with potential source and reservoir rocks.

Download Full-text

Stratigraphic architecture of the northern Oman continental margin - Mesozoic Hamrat Duru Group, Hawasina complex, Oman

GeoArabia ◽

10.2113/geoarabia090281 ◽

2004 ◽

Vol 9 (2) ◽

pp. 81-132 ◽

Cited By ~ 8

Author(s):

Ingo Blechschmidt ◽

Paulian Dumitrica ◽

Albert Mater ◽

Leopold Krystyn ◽

Tjerk Peters

Keyword(s):

Late Cretaceous ◽

Middle Jurassic ◽

Early Jurassic ◽

Late Triassic ◽

Time Interval ◽

Oman Mountains ◽

Stratigraphic Architecture ◽

Lithostratigraphic Units ◽

Nappe Complex ◽

Arabian Platform

ABSTRACT The Triassic to Late Cretaceous deep-marine sediments of the Hamrat Duru Group, Oman Mountains, represent a subunit of the Hawasina nappe-complex which was deposited in a deep marine basin. During the Late Cretaceous SSW-directed obduction of the Semail Ophiolite, the Hawasina complex was emplaced onto the autochthonous cover of the Arabian basement, while the original configuration of the basin was destroyed. New lithostratigraphic results and high-resolution radiolarian and conodont biostratigraphy lead to a revised stratigraphic scheme of the Hamrat Duru Group which conforms with the standard stratigraphical nomenclature. The Hamrat Duru Group is divided into six formations: (1) The Early Triassic (Olenekian) to Late Triassic (Upper Norian) Zulla Formation (Limestone and Shale Member, Sandstone and Shale Member, Radiolarian Chert Member and Halobia Limestone Member); (2) The Late Triassic (late Norian to Rhaetian) Al Ayn Formation; (3) The Early Jurassic (late Pliensbachian) to Middle Jurassic (early Callovian) Guwayza Formation (Tawi Sadh Member and Oolitic Limestone Member); (4) Middle Jurassic (Callovian) to Late Cretaceous (Cenomanian?) Sid’r Formation (Lower Member, Upper Member); (5) Late Cretaceous (Cenomanian? to Santonian?) Nayid Formation; and (6) Late Jurassic (early Callovian) to Early (Late?) Cretaceous Wahrah Formation. Most of the lithostratigraphic units (formations and members) show isochronous boundaries between the different outcrop areas. The stratigraphic architecture of the Hamrat Duru Group megasequence is controlled by alternating siliciclastic and carbonate sedimentation possibly related to the second-order sea-level variations. The sediments accumulated on the continental rise of the Arabian margin mostly by submarine sediment-gravity flows and hemipelagic to pelagic rainout. A close relationship of the evolution of the Arabian Platform and the adjoining slope and basinal environments is evident. Changes in carbonate supply, oceanographic circulation and/or variations in silica productivity resulted in two distinct phases of radiolarian sedimentation. The first phase corresponds to the Triassic late Anisian-early Norian time interval; the second started in the Early Jurassic late Pliensbachian and lasted, with some interruptions, up to the Late Cretaceous Coniacian. The litho- and biostratigraphic similarities between the Mesozoic Hamrat Duru Basin of the northern/central Oman Mountains and the Mesozoic Batain Basin of northeastern Oman are seen as related to Neo-Tethys-wide palaeoceanographic changes and suggest a strong interdependence of the two basins with the evolution of the Arabian Platform.

Download Full-text

Revision of Saurorhynchus (Actinopterygii: Saurichthyidae) from the Early Jurassic of England and Germany

European Journal of Taxonomy ◽

10.5852/ejt.2017.321 ◽

2017 ◽

Cited By ~ 1

Author(s):

Erin E. Maxwell ◽

Sebastian Stumpf

Keyword(s):

New Species ◽

Middle Jurassic ◽

Early Jurassic ◽

Type Material ◽

Valid Species ◽

Late Permian ◽

European Distribution ◽

Stratigraphic Ranges ◽

Cranial Osteology ◽

Diversity Estimates

Saurichthyidae is a speciose group of fishes, ranging from the Late Permian to the Middle Jurassic. Early Jurassic saurichthyids are usually considered morphologically less disparate and taxonomically less diverse than their Triassic counterparts, consisting of only two valid species. These were historically differentiated almost entirely based on cranial ratios, and both had stratigraphic ranges spanning the Early Jurassic. Here, we revise the Early Jurassic saurichthyid fishes of Europe based on restudy of the type material of Saurorhynchus brevirostris (Woodward, 1895) and S. acutus (Agassiz, 1844). We identify four species based on cranial osteology: S. acutus, S. brevirostris, S. anningae sp. nov., and S. hauffi sp. nov. Saurorhynchus brevirostris and S. anningae sp. nov. are known from the Sinemurian of England only, whereas S. acutus and S. hauffi sp. nov. share a broad European distribution during the Toarcian, from southwestern Germany to England. Saurorhynchus anningae sp. nov. and S. brevirostris, in particular, show disparity in such ecomorphologically important traits as cranial fineness, and tooth and jaw morphology. In contrast, S. acutus and S. hauffi sp. nov. show much lower levels of disparity, differing from each other in nostril morphology, dermal ornamentation, and position of the lateral extrascapular. The new species do not increase diversity estimates for Saurorhynchus in either the Sinemurian or Toarcian interval.

Download Full-text

A new species of the deep-bodied actinopterygian Dapedium from the Middle Jurassic (Aalenian) of southwestern Germany

PeerJ ◽

10.7717/peerj.5033 ◽

2018 ◽

Vol 6 ◽

pp. e5033 ◽

Cited By ~ 3

Author(s):

Erin E. Maxwell ◽

Adriana López-Arbarello

Keyword(s):

New Species ◽

Standard Length ◽

Middle Jurassic ◽

Fossil Record ◽

Evolutionary Dynamics ◽

Distinct Species ◽

Early Jurassic ◽

Large Species ◽

Unique Combination ◽

A New Species

Dapedium is one of the most abundant and diverse genera of ganoid fishes from the Early Jurassic fossil lagerstätte of Europe. In spite of its abundance, however, its timing of extinction is poorly constrained, with the youngest described material being Early Jurassic in age. We describe new diagnostic and relatively complete material of a large species of Dapedium (standard length estimated at 50 cm) from the Middle Jurassic (earliest Aalenian) Opalinuston Formation of Baden-Württemberg, Germany. The Aalenian material represents a distinct species, D. ballei sp. nov., differing from Early Jurassic species in a unique combination of characters pertaining to the shape of the dermal skull elements, pectoral fin position, and scale shape and ornamentation. However, although D. ballei sp. nov. exhibits a unique combination of characters, there are no autapomorphies with which to distinguish it from the Toarcian species of Dapedium. Dapedium ballei represents the geologically youngest species of Dapedium, extending the range of this genus into the Middle Jurassic. The Opalinuston Formation fills an important gap in the marine vertebrate fossil record, and finds from this horizon have the potential to greatly improve our understanding of evolutionary dynamics over this period of faunal transition.

Download Full-text

Reappraisal of the Mesozoic tectonic transition from the Paleo-Tethyan to Paleo-Pacific domains in South China

Geological Society of America Bulletin ◽

10.1130/b35755.1 ◽

2021 ◽

Author(s):

Chengshi Gan ◽

Yuzhi Zhang ◽

Yuejun Wang ◽

Xin Qian ◽

Yang Wang

Keyword(s):

South China ◽

Middle Jurassic ◽

Late Jurassic ◽

Sedimentary Rocks ◽

Early Jurassic ◽

Igneous Rocks ◽

Late Triassic ◽

Geochemical Data ◽

South China Block ◽

Tectonic Transition

The southeastern (SE) South China Block was mainly influenced by the Paleo-Tethyan and Paleo-Pacific dynamic domains during the Mesozoic. The initial timing of the tectonic transition between these two domains in the SE South China Block still remains debated. The transition would affect the nature of the lithosphere and material provenance of sediments, and, therefore, igneous and sedimentary rocks in the area could record such dynamic processes. In this study, published geochronological and geochemical data of the Triassic and Jurassic igneous rocks and detrital zircon data of contemporaneous sedimentary rocks in the SE South China Block were compiled, aiming to provide constraints on the tectonic transition via tracing the spatial-temporal variations in the nature of the lithosphere and sedimentary provenance signals. The compiled results suggest that the magmatic intensity and volume decreased significantly from the Late Triassic to Early−Middle Jurassic, with an obvious magmatic quiescence between them, and increased from the Early−Middle Jurassic to Late Jurassic. The εNd(t) and zircon εHf(t) values of mafic rocks, granitoids, and shoshonitic rocks remarkably increased from the Late Triassic to Early−Middle Jurassic, indicative of variations in the lithospheric mantle and continental crust. Such variations suggest that the initial tectonic transition occurred at the earliest Early Jurassic. Based on the southward paleocurrents from Early Jurassic sandstone, E-W−trending extension of Early−Middle Jurassic mafic and shoshonitic rocks, and similar sedimentary provenances of Late Triassic and Early−Middle Jurassic sedimentary rocks, these features imply that the SE South China Block was not immediately influenced by the Paleo-Pacific domain during the Early−Middle Jurassic. However, from the Early−Middle Jurassic to Late Jurassic and Early Cretaceous, the spatial distribution, geochemical signatures, magmatic intensity, and magmatic volume of igneous rocks and provenance of sedimentary rocks exhibit obvious variations, and the regional fold hinge direction changed from E-W−trending to NE-trending, suggesting significant effects from Paleo-Pacific subduction on the SE South China Block. Thus, the Mesozoic tectonic transition from the Paleo-Tethyan to the Paleo-Pacific dynamic domain in the SE South China Block likely occurred during the Early−Middle Jurassic.

Download Full-text

Sequence Strata Division and Source Bed of Coal Bed Gas Accumulation Law of Early~Middle Jurassic at Xinjiang KuBai Coalfield

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.926-930.4348 ◽

2014 ◽

Vol 926-930 ◽

pp. 4348-4352

Author(s):

Hao Wang ◽

Ling Yun Pang

Keyword(s):

Middle Jurassic ◽

Depositional Environment ◽

Early Jurassic ◽

Coal Bed ◽

Environment Analysis ◽

Gas Accumulation ◽

Accumulation Effect ◽

Coal Accumulation

The coal accumulation effect occurred at KuBai Coalfield in the early~middle Jurassic, including three major coal-bearing strata: Tarja Chick and Yangxia Group of Early Jurassic, and Kezilenuer group of Middle Jurassic. This article makes the contrast segment of 20 tie-well sequence strata by dividing the sequence strata and analyzing the depositional environment analysis of 85 drilling wells at Jurassic strata of KuBai Basin. By overall analyzing the materials of drilling, logging, outcropping, core and paleontology, it establishes the contrast framework of isochronal sequence strata with the unit of tertiary sequence at Jurassic strata of KuBai Basin. It also studies the sequence strata and Lithofacies of each sequence, and analyzes the coal accumulation law at Jurassic strata of KuBai Coalfield.

Download Full-text

Depth-Dependent Transformation of Kaolinite to Dickite In Sandstones of the Norwegian Continental Shelf

Clay Minerals ◽

10.1180/claymin.1993.028.3.01 ◽

1993 ◽

Vol 28 (3) ◽

pp. 325-352 ◽

Cited By ~ 123

Author(s):

S. N. Ehrenberg ◽

P. Aagaard ◽

M. J. Wilson ◽

A. R. Fraser ◽

D. M. L. Duthie

Keyword(s):

Solid State ◽

Continental Shelf ◽

Middle Jurassic ◽

Morphological Difference ◽

Structural Difference ◽

Early Jurassic ◽

Late Triassic ◽

Sea Floor ◽

Depth Of Burial ◽

Norwegian Continental Shelf

AbstractReplacement of kaolinite by dickite has been observed to occur with increasing depth of burial in sandstones from three different basins on the Norwegian continental shelf. In the Garn Formation (Middle Jurassic) of Haltenbanken, samples from 1.4-2-7 km below the sea floor (110°C) contain kaolinite, whereas deeper than 3.2 km (130°C) mainly dickite is present. In the Statfjord Formation (Late Triassic-Early Jurassic) from Gullfaks and Gullfaks Sør Fields, transformation of kaolinite to dickite occurs at ~3.1 km below the sea floor (120°C) From the Stø and Nordmela Formations (Lower to Middle Jurassic) to the Troms Area, kaolin polytypes have been identified in only two shallow and two deep samples, but the results are consistent with the transformation depth determined in two other areas studied. These occurrences are significant because they allow the temperature of the kaolinite/dickite transformation to be established with greater confidence than had been possible previously. Also the observation of this transformation in all three areas so far examined indicates that it may be a general and predictable feature of kaolinbearing sandstones worldwide and therefore a potentially reliable paleogeothermometer. In most cases, the kaolinite occurs as relatively large vermicular crystals, whereas dickite forms more euhedral, blockier crystals. This morphological difference, together with the nature of the structural difference in octahedral occupancy between the kaolinite and dickite, suggests that the transformation occurs by dissolution and reprecipitation, rather then in the solid state.

Download Full-text

Paleoclimatic and Redox Condition Changes during Early-Middle Jurassic in the Yili Basin, Northwest China

Minerals ◽

10.3390/min11070675 ◽

2021 ◽

Vol 11 (7) ◽

pp. 675

Author(s):

Hui Chao ◽

Mingcai Hou ◽

Wenjian Jiang ◽

Haiyang Cao ◽

Xiaolin Chang ◽

...

Keyword(s):

Middle Jurassic ◽

Northwest China ◽

Early Jurassic ◽

Coal Seams ◽

High Productivity ◽

Fine Grained ◽

Palynological Assemblages ◽

Continental Arc ◽

Terrestrial Sediments ◽

Peat Formation

The Jurassic was mainly a “greenhouse” period characterized by global warming and by significant peat accumulations in some continental basins. However, studies of Jurassic climate and environments have mainly focused on marine records and only a few on terrestrial sediments. Yili Basin, a mid-latitude terrestrial basin in present Northwest China, included accumulation of the important recoverable coal seams. In this study, geological data, clay mineral analysis, and palynological assemblages were employed on fine-grained samples from the Su’asugou section in southern Yili Basin. The factors (paleoclimate, depositional conditions, and paleo-vegetation) impacting peat accumulation were investigated. The results suggest that the siliciclastics may have been derived from exposed Carboniferous rocks in a continental arc environment. A warm and humid paleoclimate in the Yili basin dominated during the early-Early Jurassic deposition of the Badaowan Formation and the Middle Jurassic deposition of the Xishanyao Formation. This climate contributed to high sedimentary rates and to a high productivity of peat-forming paleo-vegetation that was preserved under dysoxic conditions. In contrast, during the late-Early Jurassic between these two formations, the Sangonghe Formation was an interval of relatively aridity that included red beds preserved under more hypoxic sedimentary conditions, and with an interruption in peat formation and preservation.

Download Full-text