Tracking coarse-grained gravity flows by LASS-ICP-MS depth-profiling of detrital zircon (Aveto Formation, Adriatic foredeep, Italy)

ABSTRACT: Two important Proterozoic metasedimentary sequences, the Rio Preto and Santo Onofre Groups, crop out along the northwestern margin of the São Francisco craton and in northern Paramirim corridor, respectively. The Rio Preto Group, involved in the eponymous fold-thrust belt along the northwestern cratonic boundary, comprises the Formosa (garnet schist, quartz-mica schist, quartzite, chlorite-sericite schist and ferriferous quartz schist) and Canabravinha (quartzite, micaceous quartzite, metarhytmite, phylite, schist and metaturbidite) formations. The Santo Onofre Group occurs exclusively in the Paramirim corridor, and is composed of quartzite and minor carbonaceous or Mn-rich phylite. These units record sedimentation in shallow to deep-water marine settings related to rift basins, and were deformed and metamorphosed under greenschist facies conditions during the Brasiliano orogeny. Here we present 427 new detrital zircon U-Pb ages, which constrain the maximum depositional ages of ca. 971 Ma for the Santo Onofre Group, ca. 912 Ma for the Canabravinha Formation, and ca. 965 Ma for the Formosa Formation of the Rio Preto Group. Our data suggests that the Santo Onofre and the Rio Preto Groups accumulated in two distinct basin settings. The latter, composed mostly of sandy rocks, would represent a relatively stable, shallow-marine shelf environment. The Rio Preto Group, with metadiamictite, quartzite, pelitic and rhythmitic rocks, represents a shallow to deep marine environment influenced by gravity flows. Both groups were probably deposited in the Late Tonian, and are potential correlatives of the lower (pre-glacial) units of the Macaúbas Group of the Araçuaí belt.

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PROVENANCE ANALYSIS OF EOCENE TO MIOCENE SEDIMENTARY STRATA DERIVED FROM THE CENTRAL ALPS - INSIGHTS FROM DETRITAL ZIRCON LASER ABLATION SPLIT STREAM (LASS)-ICP-MS DEPTH-PROFILING

10.1130/abs/2020am-358376 ◽

2020 ◽

Author(s):

Owen A. Anfinson ◽

◽

Daniel F. Stockli ◽

Fritz Schlunegger ◽

Marco G. Malusa

Keyword(s):

Laser Ablation ◽

Detrital Zircon ◽

Depth Profiling ◽

Central Alps ◽

Provenance Analysis ◽

Icp Ms

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THE PROVENANCE OF GLACIAL TILL DEPOSITED IN ONG VALLEY, CENTRAL TRANSANTARCTIC MOUNTAINS DETERMINED BY LA-ICP-MS OF DETRITAL ZIRCON

10.1130/abs/2016am-285013 ◽

2016 ◽

Author(s):

Evan J. Miranda ◽

◽

Daniel Morgan ◽

Jaakko Putkonen ◽

Greg Balco ◽

...

Keyword(s):

Detrital Zircon ◽

Glacial Till ◽

Icp Ms ◽

Transantarctic Mountains

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U–Pb age and Lu–Hf signatures of detrital zircon from Palaeozoic sandstones in the Oslo Rift, Norway

Geological Magazine ◽

10.1017/s0016756813000885 ◽

2013 ◽

Vol 151 (5) ◽

pp. 816-829 ◽

Cited By ~ 21

Author(s):

MAGNUS KRISTOFFERSEN ◽

TOM ANDERSEN ◽

ARILD ANDRESEN

Keyword(s):

Detrital Zircon ◽

Inductively Coupled Plasma ◽

Late Carboniferous ◽

Isotopic Signatures ◽

Inductively Coupled ◽

Source To Sink ◽

Icp Ms ◽

Plasma Mass Spectrometry ◽

Isotope Analyses ◽

Multiple Episodes

AbstractU–Pb and Lu–Hf isotope analyses of detrital zircon from the latest Ordovician (Hirnantian) Langøyene Formation, the Late Silurian Ringerike Group and the Late Carboniferous Asker Group in the Oslo Rift were obtained by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Overall the U–Pb dating yielded ages within the range 2861–313 Ma. The U–Pb age and Lu–Hf isotopic signatures correspond to virtually all known events of crustal evolution in Fennoscandia, as well as synorogenic intrusions from the Norwegian Caledonides. Such temporally and geographically diverse source areas likely reflect multiple episodes of sediment recycling in Fennoscandia, and highlights the intrinsic problem of using zircon as a tracer-mineral in ‘source to sink’ sedimentary provenance studies. In addition to its mostly Fennoscandia-derived detritus, the Asker Group also have zircon grains of Late Devonian – Late Carboniferous age. Since no rocks of these ages are known in Fennoscandia, these zircons are inferred to be derived from the Variscan Orogen of central Europe.

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Dating Micrometre-Thin Rims Using a LA-ICP-MS Depth Profiling Technique on Zircon from an Archaean Metasediment: Comparison with the SIMS Depth Profiling Method

Geostandards and Geoanalytical Research ◽

10.1111/j.1751-908x.2014.00314.x ◽

2014 ◽

Vol 38 (4) ◽

pp. 389-407 ◽

Cited By ~ 20

Author(s):

Colter J. Kelly ◽

Christopher R.M. McFarlane ◽

David A. Schneider ◽

Simon E. Jackson

Keyword(s):

Depth Profiling ◽

Icp Ms ◽

Sims Depth Profiling

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Caledonian terrane amalgamation of Svalbard: detrital zircon provenance of Mesoproterozoic to Carboniferous strata from Oscar II Land, western Spitsbergen

Geological Magazine ◽

10.1017/s0016756813000174 ◽

2013 ◽

Vol 150 (6) ◽

pp. 1103-1126 ◽

Cited By ~ 33

Author(s):

DETA GASSER ◽

ARILD ANDRESEN

Keyword(s):

Detrital Zircon ◽

Large Scale ◽

Strike Slip ◽

Western Coast ◽

Zircon Age ◽

The North ◽

Tectonic History ◽

Icp Ms ◽

Depositional Age ◽

Sveconorwegian Orogen

AbstractThe tectonic origin of pre-Devonian rocks of Svalbard has long been a matter of debate. In particular, the origin and assemblage of pre-Devonian rocks of western Spitsbergen, including a blueschist-eclogite complex in Oscar II Land, are enigmatic. We present detrital zircon U–Pb LA-ICP-MS data from six Mesoproterozoic to Carboniferous samples and one U–Pb TIMS zircon age from an orthogneiss from Oscar II Land in order to discuss tectonic models for this region. Variable proportions of Palaeo- to Neoproterozoic detritus dominate the metasedimentary samples. The orthogneiss has an intrusion age of 927 ± 3 Ma. Comparison with detrital zircon age spectra from other units of similar depositional age within the North Atlantic region indicates that Oscar II Land experienced the following tectonic history: (1) the latest Mesoproterozoic sequence was part of a successor basin which originated close to the Grenvillian–Sveconorwegian orogen, and which was intruded byc. 980–920 Ma plutons; (2) the Neoproterozoic sediments were deposited in a large-scale basin which stretched along the Baltoscandian margin; (3) the eclogite-blueschist complex and the overlying Ordovician–Silurian sediments probably formed to the north of the Grampian/Taconian arc; (4) strike-slip movements assembled the western coast of Spitsbergen outside of, and prior to, the main Scandian collision; and (5) the remaining parts of Svalbard were assembled by strike-slip movements during the Devonian. Our study confirms previous models of complex Caledonian terrane amalgamation with contrasting tectonic histories for the different pre-Devonian terranes of Svalbard and particularly highlights the non-Laurentian origin of Oscar II Land.

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Evolution of the early Mesozoic Cordilleran arc: The detrital zircon record of back-arc basin deposits, Triassic Buckskin Formation, western Arizona and southeastern California, USA

Geosphere ◽

10.1130/ges02193.1 ◽

2020 ◽

Vol 16 (4) ◽

pp. 1042-1057

Author(s):

N.R. Riggs ◽

T.B. Sanchez ◽

S.J. Reynolds

Keyword(s):

North America ◽

Detrital Zircon ◽

Colorado Plateau ◽

Depositional Environments ◽

Coarse Grained ◽

Land Bridge ◽

Magmatic Arc ◽

Early Mesozoic ◽

Northern Nevada ◽

Back Arc

Abstract A shift in the depositional systems and tectonic regime along the western margin of Laurentia marked the end of the Paleozoic Era. The record of this transition and the inception and tectonic development of the Permo-Triassic Cordilleran magmatic arc is preserved in plutonic rocks in southwestern North America, in successions in the distal back-arc region on the Colorado Plateau, and in the more proximal back-arc region in the rocks of the Buckskin Formation of southeastern California and west-central Arizona (southwestern North America). The Buckskin Formation is correlated to the Lower–Middle Triassic Moenkopi and Upper Triassic Chinle Formations of the Colorado Plateau based on stratigraphic facies and position and new detrital zircon data. Calcareous, fine- to medium-grained and locally gypsiferous quartzites (quartz siltstone) of the lower and quartzite members of the Buckskin Formation were deposited in a marginal-marine environment between ca. 250 and 245 Ma, based on detrital zircon U-Pb data analysis, matching a detrital-zircon maximum depositional age of 250 Ma from the Holbrook Member of the Moenkopi Formation. An unconformity that separates the quartzite and phyllite members is inferred to be the Tr-3 unconformity that is documented across the Colorado Plateau, and marks a transition in depositional environments. Rocks of the phyllite and upper members were deposited in wholly continental depositional environments beginning at ca. 220 Ma. Lenticular bodies of pebble to cobble (meta) conglomerate and medium- to coarse-grained phyllite (subfeldspathic or quartz wacke) in the phyllite member indicate deposition in fluvial systems, whereas the fine- to medium-grained beds of quartzite (quartz arenite) in the upper member indicate deposition in fluvial and shallow-lacustrine environments. The lower and phyllite members show very strong age and Th/U overlap with grains derived from Cordilleran arc plutons. A normalized-distribution plot of Triassic ages across southwestern North America shows peak magmatism at ca. 260–250 Ma and 230–210 Ma, with relatively less activity at ca. 240 Ma, when a land bridge between the arc and the continent was established. Ages and facies of the Buckskin Formation provide insight into the tectono-magmatic evolution of early Mesozoic southwestern North America. During deposition of the lower and quartzite members, the Cordilleran arc was offshore and likely dominantly marine. Sedimentation patterns were most strongly influenced by the Sonoma orogeny in northern Nevada and Utah (USA). The Tr-3 unconformity corresponds to both a lull in magmatism and the “shoaling” of the arc. The phyllite and upper members were deposited in a sedimentary system that was still influenced by a strong contribution of detritus from headwaters far to the southeast, but more locally by a developing arc that had a far stronger effect on sedimentation than the initial phases of magmatism during deposition of the basal members.

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Mineralogy of Zirconium in Iron-Oxides: A Micron- to Nanoscale Study of Hematite Ore from Peculiar Knob, South Australia

Minerals ◽

10.3390/min9040244 ◽

2019 ◽

Vol 9 (4) ◽

pp. 244 ◽

Cited By ~ 7

Author(s):

Keyser ◽

Ciobanu ◽

Cook ◽

Feltus ◽

Johnson ◽

...

Keyword(s):

South Australia ◽

Coarse Grained ◽

Iron Deposit ◽

High Grade ◽

Microscopy Imaging ◽

Grade Metamorphism ◽

Icp Ms ◽

High Grade Metamorphism ◽

Hematite Ore

Zirconium is an element of considerable petrogenetic significance but is rarely found in hematite at concentrations higher than a few parts-per-million (ppm). Coarse-grained hematite ore from the metamorphosed Peculiar Knob iron deposit, South Australia, contains anomalous concentrations of Zr and has been investigated using microanalytical techniques that can bridge the micron- to nanoscales to understand the distribution of Zr in the ore. Hematite displays textures attributable to annealing under conditions of high-grade metamorphism, deformation twins (r~85˚ to hematite elongation), relict magnetite and fields of sub-micron-wide inclusions of baddeleyite as conjugate needles with orientation at ~110˚/70˚. Skeletal and granoblastic zircon, containing only a few ppm U, are both present interstitial to hematite. Using laser-ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) spot analysis and mapping, the concentration of Zr in hematite is determined to be ~260 ppm on average (up to 680 ppm). The Zr content is, however, directly attributable to nm-scale inclusions of baddeleyite pervasively distributed throughout the hematite rather than Zr in solid solution. Distinction between nm-scale inclusions and lattice-bound trace element substitutions cannot be made from LA-ICP-MS data alone and requires nanoscale characterization. Scandium-rich (up to 0.18 wt. % Sc2O3) cores in zircon are documented by microprobe analysis and mapping. Using high-angle annular dark field scanning transmission electron microscopy imaging (HAADF-STEM) and energy-dispersive spectrometry STEM mapping of foils prepared in-situ by focused ion beam methods, we identify [011]baddeleyite epitaxially intergrown with [22.1]hematite. Lattice vectors at 84–86˚ underpinning the epitaxial intergrowth orientation correspond to directions of r-twins but not to the orientation of the needles, which display a ~15˚ misfit. This is attributable to directions of trellis exsolutions in a precursor titanomagnetite. U–Pb dating of zircon gives a 206Pb/238U weighted mean age of 1741 ± 49 Ma (sensitive high-resolution ion microprobe U–Pb method). Based on the findings presented here, detrital titanomagnetite from erosion of mafic rocks is considered the most likely source for Zr, Ti, Cr and Sc. Whether such detrital horizons accumulated in a basin with chemical precipitation of Fe-minerals (banded iron formation) is debatable, but such Fe-rich sediments clearly included detrital horizons. Martitization during the diagenesis-supergene enrichment cycle was followed by high-grade metamorphism during the ~1.73–1.69 Ga Kimban Orogeny during which martite recrystallized as granoblastic hematite. Later interaction with hydrothermal fluids associated with ~1.6 Ga Hiltaba-granitoids led to W, Sn and Sb enrichment in the hematite. By reconstructing the evolution of the massive orebody at Peculiar Knob, we show how application of complimentary advanced microanalytical techniques, in-situ and on the same material but at different scales, provides critical constraints on ore-forming processes.

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