scholarly journals Multi-Proxy Provenance Analyses of the Kingriali and Datta Formations (Triassic—Jurassic Transition): Evidence for Westward Extension of the Neo-Tethys Passive Margin from the Salt Range (Pakistan)

Minerals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 573
Author(s):  
Shahid Iqbal ◽  
Michael Wagreich ◽  
Mehwish Bibi ◽  
Irfan U. Jan ◽  
Susanne Gier

The Salt Range, in Pakistan, preserves an insightful sedimentary record of passive margin dynamics along the NW margin of the Indian Plate during the Mesozoic. This study develops provenance analyses of the Upper Triassic (Kingriali Formation) to Lower Jurassic (Datta Formation) siliciclastics from the Salt and Trans Indus ranges based on outcrop analysis, petrography, bulk sediment elemental geochemistry, and heavy-mineral data. The sandstones are texturally and compositionally mature quartz arenites and the conglomerates are quartz rich oligomictic conglomerates. Geochemical proxies support sediment derivation from acidic sources and deposition under a passive margin setting. The transparent heavy mineral suite consists of zircon, tourmaline, and rutile (ZTR) with minor staurolite in the Triassic strata that diminishes in the Jurassic strata. Together, these data indicate that the sediments were supplied by erosion of the older siliciclastics of the eastern Salt Range and adjoining areas of the Indian Plate. The proportion of recycled component exceeds the previous literature estimates for direct sediment derivation from the Indian Shield. A possible increase in detritus supply from the Salt Range itself indicates notably different conditions of sediment generation, during the Triassic–Jurassic transition. The present results suggest that, during the Triassic–Jurassic transition in the Salt Range, direct sediment supply from the Indian Shield was probably reduced and the Triassic and older siliciclastics were exhumed on an elevated passive margin and reworked by a locally established fluvio-deltaic system. The sediment transport had a north-northwestward trend parallel to the northwestern Tethyan margin of the Indian Plate and normal to its opening axis. During the Late Triassic, hot and arid hot-house palaeoclimate prevailed in the area that gave way to a hot and humid greenhouse palaeoclimate across the Triassic–Jurassic Boundary. Sedimentological similarity between the Salt Range succession and the Neo-Tethyan succession exposed to the east on the northern Indian passive Neo-Tethyan margin suggests a possible westward extension of this margin.

2021 ◽  
pp. 1-13
Author(s):  
Jasper Verhaegen ◽  
Hilmar von Eynatten ◽  
István Dunkl ◽  
Gert Jan Weltje

Abstract Heavy mineral analysis is a long-standing and valuable tool for sedimentary provenance analysis. Many studies have indicated that heavy mineral data can also be significantly affected by hydraulic sorting, weathering and reworking or recycling, leading to incomplete or erroneous provenance interpretations if they are used in isolation. By combining zircon U–Pb geochronology with heavy mineral data for the southern North Sea Basin, this study shows that the classic model of sediment mixing between a northern and a southern source throughout the Neogene is more complex. In contrast to the strongly variable heavy mineral composition, the zircon U–Pb age spectra are mostly constant for the studied samples. This provides a strong indication that most zircons had an initial similar northern source, yet the sediment has undergone intense chemical weathering on top of the Brabant Massif and Ardennes in the south. This weathered sediment was later recycled into the southern North Sea Basin through local rivers and the Meuse, leading to a weathered southern heavy mineral signature and a fresh northern heavy mineral signature, yet exhibiting a constant zircon U–Pb age signature. Thus, this study highlights the necessity of combining multiple provenance proxies to correctly account for weathering, reworking and recycling.


2004 ◽  
Vol 41 (1) ◽  
pp. 103-125 ◽  
Author(s):  
Nathan T Petersen ◽  
Paul L Smith ◽  
James K Mortensen ◽  
Robert A Creaser ◽  
Howard W Tipper

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, Sm–Nd 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 Sm–Nd 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.


1986 ◽  
Vol 5 (1) ◽  
pp. 19-29 ◽  
Author(s):  
Nigel R. Ainsworth ◽  
Nicola F. Horton

Abstract. The geology, biostratigraphy and palaeoecology of exploration well Elf 55/30–1 in the Fastnet Basin are summarised. The biostratigraphical and ecological distribution of the foraminifera and Ostracoda from the late Triassic, the Lower Jurassic and the Lower Cretaceous are reviewed with reference to microfaunas elsewhere in Europe. Selected microfossil taxa are illustrated.


1998 ◽  
Vol 16 (2-3) ◽  
pp. 173-194 ◽  
Author(s):  
Flavio Jadoul ◽  
Fabrizio Berra ◽  
Eduardo Garzanti

2021 ◽  
pp. M57-2021-31
Author(s):  
Harald Brekke ◽  
Halvor S. S. Bunkholt ◽  
Jan I. Faleide ◽  
Michael B. W. Fyhn

AbstractThe geology of the conjugate continental margins of the Norwegian and Greenland Seas reflects 400 Ma of post-Caledonian continental rifting, continental breakup between early Eocene and Miocene times, and subsequent passive margin conditions accompanying seafloor spreading. During Devonian-Carboniferous time, rifting and continental deposition prevailed, but from the mid-Carboniferous, rifting decreased and marine deposition commenced in the north culminating in a Late Permian open seaway as rifting resumed. The seaway became partly filled by Triassic and Lower Jurassic sediments causing mixed marine/non-marine deposition. A permanent, open seaway established by the end of the Early Jurassic and was followed by the development of an axial line of deep marine Cretaceous basins. The final, strong rift pulse of continental breakup occurred along a line oblique to the axis of these basins. The Jan Mayen Micro-Continent formed by resumed rifting in a part of the East Greenland margin in Eocene to Miocene times. This complex tectonic development is reflected in the sedimentary record in the two conjugate margins, which clearly shows their common pre-breakup geological development. The strong correlation between the two present margins is the basis for defining seven tectono-sedimentary elements (TSE) and establishing eight composite tectono-sedimentary elements (CTSE) in the region.


2017 ◽  
Author(s):  
Paul M Barrett ◽  
Tim Broderick ◽  
Kimberley Chapelle ◽  
Jonah Choiniere ◽  
Steve Edwards ◽  
...  

Southern Africa provides critical information on Late Triassic–Early Jurassic terrestrial tetrapod faunas. Most of the localities in this region are in South Africa and Lesotho, but preliminary work in Zimbabwe has revealed significant potential. Early Jurassic Zimbabwean localities have yielded the basal sauropodomorph Massospondylus, the early sauropod Vulcanodon and theropod material. Late Triassic localities are also known, but have yielded only fragmentary specimens thus far. In early 2017, a joint South African-Zimbabwean-UK team conducted fieldwork in the upper Karoo-aged deposits along the shores of Lake Kariba, northern Zimbabwe (Mid-Zambesi Basin). We relocated the Vulcanodon type locality on Island 126/127 and found that, contrary to previous reports suggesting a Toarcian age, the quarry was in a horizon pre-dating the onset of Drakensburg volcanism (= Batoka Basalts). It is situated instead within the earlier Lower Jurassic Forest Sandstone. This indicates that Vulcanodon is 10–15 million years older than thought previously, recalibrating several nodes within Sauropoda and indicating extensive overlap between true sauropods and 'prosauropods'. Other new vertebrate localities show that sauropodomorphs are present in the Forest Sandstone and upper Tashinga (Late Triassic) formations, but a grey mudstone facies within the Pebbly Arkose Member of the latter unit yields a more aquatic fauna, including lungfish and phytosaurs, but lacking sauropodomorphs. The phytosaur occurrence is the first in Africa south of the Sahara. Faunal and sedimentological evidence indicates that the Late Triassic and Early Jurassic sites in this region were deposited under more mesic environments than their lateral equivalents in South Africa.


2012 ◽  
Vol 49 (12) ◽  
pp. 1463-1477 ◽  
Author(s):  
Gang Li ◽  
Georgia Pe-Piper ◽  
David J.W. Piper

The tectonic and geomorphological evolution of the Scotian margin and its hinterland is poorly known between Late Triassic rifting and the Early Cretaceous progradation of major deltas. This study determined sedimentary provenance of Middle Jurassic Mohican Formation sandstones from three wells using heavy minerals and mineral chemistry. Indicator minerals such as xenotime, altered ilmenite, and varietal types of garnet and tourmaline are similar to those in Hauterivian–Barremian sandstones in the western Scotian Basin, which are almost exclusively derived from the Meguma terrane. The wells adjacent to the Canso Ridge have more zircon and less ilmenite, indicating a greater contribution of polycyclic reworking, but with an ultimate source in the Meguma terrane. Zircon and ilmenite were likely derived in part from Carboniferous sandstones in eastern mainland Nova Scotia and Cape Breton Island. Any river drainage from the inboard terranes of the Appalachians either was diverted through the Fundy Basin or entered the easternmost Scotian Basin, where the Mohican Formation is 5.5 km thick, along the linear continuation of the southwest Grand Banks transform. Such sediment did not reach the Canso Ridge, suggesting that the Cobequid–Chedabucto fault zone in Orpheus graben was not a significant physiographic feature. This tectonically controlled paleogeography in the Middle Jurassic is quite different from that during active rifting in the Late Triassic – Early Jurassic. Middle Jurassic quiescence was followed in the Tithonian – Early Cretaceous by renewed tectonic uplift associated with rifting of Grand Banks from Iberia and Labrador from Greenland.


Minerals ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 457 ◽  
Author(s):  
Wendong Liang ◽  
Eduardo Garzanti ◽  
Sergio Andò ◽  
Paolo Gentile ◽  
Alberto Resentini

As a Quaternary repository of wind-reworked Indus River sand at the entry point in the Himalayan foreland basin, the Thal Desert in northern Pakistan stores mineralogical information useful to trace erosion patterns across the western Himalayan syntaxis and the adjacent orogenic segments that fed detritus into the Indus delta and huge deep-sea fan throughout the Neogene. Provenance analysis of Thal Desert sand was carried out by applying optical and semi-automated Raman spectroscopy on heavy-mineral suites of four eolian and 11 fluvial sand samples collected in selected tributaries draining one specific tectonic domain each in the upper Indus catchment. In each sample, the different types of amphibole, garnet, epidote and pyroxene grains—the four dominant heavy-mineral species in orogenic sediment worldwide—were characterized by SEM-EDS spectroscopy. The chemical composition of 4249 grains was thus determined. Heavy-mineral concentration, the relative proportion of heavy-mineral species, and their minerochemical fingerprints indicate that the Kohistan arc has played the principal role as a source, especially of pyroxene and epidote. Within the western Himalayan syntaxis undergoing rapid exhumation, the Southern Karakorum belt drained by the Hispar River and the Nanga Parbat massif were revealed as important sources of garnet, amphibole, and possibly epidote. Sediment supply from the Greater Himalaya, Lesser Himalaya, and Subhimalaya is dominant only for Punjab tributaries that join the Indus River downstream and do not contribute sand to the Thal Desert. The detailed compositional fingerprint of Thal Desert sand, if contrasted with that of lower course tributaries exclusively draining the Himalaya, provides a semi-actualistic key to be used, in conjunction with complementary provenance datasets and geological information, to reconstruct changes in paleodrainage and unravel the relationship between climatic and tectonic forces that controlled the erosional evolution of the western Himalayan-Karakorum orogen in space and time.


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