Detrital zircon ages and the origins of the Nashoba terrane and Merrimack belt in southeastern New England, USA

2021 ◽  
Vol 57 ◽  
pp. 343-396
Author(s):  
J. Christopher Hepburn ◽  
Yvette D. Kuiper ◽  
Kristin J. McClary ◽  
MaryEllen L. Loan ◽  
Michael Tubrett ◽  
...  
Keyword(s):  
New England ◽  
Detrital Zircon ◽  
Inductively Coupled Plasma ◽  
Sedimentary Rocks ◽  
Detrital Zircons ◽  
Mass Spectrometry Analysis ◽  
Zircon Age ◽  
Spectrometry Analysis ◽  
Middle Ordovician ◽  
Nashoba Terrane

The fault-bounded Nashoba–Putnam terrane, a metamorphosed early Paleozoic, Ganderian arc/back-arc complex in SE New England, lies between rocks of Avalonian affinity to the southeast and middle Paleozoic sedimentary rocks, interpreted as cover on Ganderian basement, in the Merrimack belt to the northwest. U–Pb detrital zircon laser ablation inductively coupled plasma mass spectrometry analysis were conduced on six samples from the Nashoba terrane in Massachusetts and seven samples associated with the Merrimack belt in Massachusetts and SE New Hampshire to investigate their depositional ages and provenance. Samples from the Nashoba terrane yielded major age populations between ~560 and ~540 Ma, consistent with input from local sources formed during the Ediacaran–Cambrian Penobscot orogenic cycle and its basement rocks. Youngest detrital zircons in the terrane, however, are as young as the Early to Middle Ordovician. Six formations from the Merrimack belt were deposited between ~435 and 420 Ma based on youngest zircon age populations and crosscutting plutons, and yielded large ~470–443 Ma age populations. Three of these formations show only Gondwanan provenance. Three others have a mixed Gondwanan-Laurentian signal, which is known to be typical for younger and/or more westerly sedimentary rocks and may indicate that they are the youngest deposits in the Merrimack belt (late Silurian to early Devonian) and/or have been deposited in the equivalent of the more westerly Central Maine basin. Detrital zircon age populations from the Tower Hill Formation, along the faulted contact between the Merrimack belt and Nashoba terrane, are different from either of these tectonic domains and may indicate that the boundary is complex.

Enigmatic provenance signature of sandstone from the Okwa Group, Botswana

2020 ◽  
Vol 123 (3) ◽  
pp. 331-342
Author(s):  
T. Andersen ◽  
M.A. Elburg ◽  
J. Lehmann
Keyword(s):  
South Africa ◽  
Detrital Zircon ◽  
Sedimentary Rock ◽  
Age Distribution ◽  
Sedimentary Rocks ◽  
Detrital Zircons ◽  
Significant Shift ◽  
Zircon Age ◽  
Three Samples ◽  
Isotope Distributions

Abstract Detrital zircon grains from three samples of sandstone from the Tswaane Formation of the Okwa Group of Botswana have been dated by U-Pb and analysed for Hf isotopes by multicollector LA-ICPMS. The detrital zircon age distribution pattern of the detrital zircons is dominated by a mid-Palaeoproterozoic age fraction (2 000 to 2 150 Ma) with minor late Archaean – early Palaeoproterozoic fractions. The 2 000 to 2 150 Ma zircon grains show a range of epsilon Hf from -12 to 0. The observed age and Hf isotope distributions overlap closely with those of sandstones of the Palaeoproterozoic Waterberg Group and Keis Supergroup of South Africa, but are very different from Neoproterozoic deposits in the region, and from the Takatswaane siltstone of the Okwa Group, all of which are dominated by detrital zircon grains younger than 1 950 Ma. The detrital zircon data indicate that the sources of Tswaane Formation sandstones were either Palaeoproterozoic rocks in the basement of the Kaapvaal Craton, or recycled Palaeoproterozoic sedimentary rocks similar to the Waterberg, Elim or Olifantshoek groups of South Africa. This implies a significant shift in provenance regime between the deposition of the Takatswaane and Tswaane formations. However, the detrital zircon data are also compatible with a completely different scenario in which the Tswaane Formation consists of Palaeoproterozoic sedimentary rock in tectonic rather than depositional contact with the other units of the Okwa Group.

Detrital zircon geochronology of the Aycross Formation (Eocene) near Togwotee Pass, western Wind River Basin, Wyoming

2017 ◽  
Vol 54 (2) ◽  
pp. 69-85 ◽  
Author(s):  
David Malone ◽  
John Craddock ◽  
Kacey Garber ◽  
Jarek Trela
Keyword(s):  
Late Cretaceous ◽  
Detrital Zircon ◽  
Inductively Coupled Plasma ◽  
Middle Eocene ◽  
Detrital Zircons ◽  
Zircon Age ◽  
Detrital Zircon Geochronology ◽  
Inductively Coupled ◽  
Wind River Basin ◽  
The North

The Aycross Formation is the basal unit of the Absaroka Volcanic Supergroup in the southern Absaroka Range and consists of volcanic sandstone, mudstone, breccia, tuff and conglomerate. The Aycross was deposited during the waning stages of the Laramide Orogeny and the earliest phases of volcanism in the Absaroka Range. U-Pb geo-chronology using laser ablation multicollector inductively coupled plasma mass spectrometry LA-ICP-MS was performed on detrital zircons collected from an Aycross sandstone bed at Falls Campground east of Togwotee Pass. The detrital zircon age spectrum ranged fom ca 47 to 2856 Ma. Peak ages, as indicated by the zircon age probability density plot are ca. 51, 61, and 72 Ma. Tertiary zircons were the most numerous (n = 32), accounting for 42% of the zircon ages spectrum. Of these 19 are Eocene, and 13 are Paleocene, which are unusual ages in the Wyoming-Idaho-Montana area. Mesozoic zircons (n = 21) comprise 27% of the age spectrum and range in age from 68–126 Ma; all but one being late Cretaceous in age. No Paleozoic zircons are present. Proterozoic zircons range in age from 1196–2483 Ma, and also consist of 27% of the age spectrum. The maximum depositional age of the Aycross Formation is estimated to be 50.05 +/− 0.65 Ma based on weighted mean of the eight youngest grains. The Aycross Formation detrital zircon age spectrum is distinct from that of other 49–50 Ma rocks in northwest Wyoming, which include the Hominy Peak and Wapiti Formations and Crandall Conglomerate. The Aycross must have been derived largely from distal westerly source areas, which include the late Cretaceous and Paleocene Bitteroot Lobe of the Idaho Batholith. In contrast, the middle Eocene units further to the north must have been derived from erosion of the Archean basement-cored uplift of the Laramide Foreland in southwest Montana.

Preliminary detrital zircon U-Pb Geochronology of the Wasatch Formation, Powder River Basin, Wyoming

2019 ◽  
Vol 56 (3) ◽  
pp. 247-266
Author(s):  
Ian Anderson ◽  
David H. Malone ◽  
John Craddock
Keyword(s):  
River Basin ◽  
Detrital Zircon ◽  
Middle Part ◽  
Detrital Zircons ◽  
Powder River Basin ◽  
Zircon Age ◽  
Lower Eocene ◽  
The North ◽  
Mountain Front ◽  
Fluvial Sandstone

The lower Eocene Wasatch Formation is more than 1500 m thick in the Powder River Basin of Wyoming. The Wasatch is a Laramide synorgenic deposit that consists of paludal and lacustrine mudstone, fluvial sandstone, and coal. U-Pb geochronologic data on detrital zircons were gathered for a sandstone unit in the middle part of the succession. The Wasatch was collected along Interstate 90 just west of the Powder River, which is about 50 km east of the Bighorn Mountain front. The sandstone is lenticular in geometry and consists of arkosic arenite and wacke. The detrital zircon age spectrum ranged (n=99) from 1433-2957 Ma in age, and consisted of more than 95% Archean age grains, with an age peak of about 2900 Ma. Three populations of Archean ages are evident: 2886.6±10 Ma (24%), 2906.6±8.4 Ma (56%) and 2934.1±6.6 Ma (20%; all results 2 sigma). These ages are consistent with the age of Archean rocks exposed in the northern part of the range. The sparse Proterozoic grains were likely derived from the recycling of Cambrian and Carboniferous strata. These sands were transported to the Powder River Basin through the alluvial fans adjacent to the Piney Creek thrust. Drainage continued to the north through the basin and eventually into the Ancestral Missouri River and Gulf of Mexico. The provenance of the Wasatch is distinct from coeval Tatman and Willwood strata in the Bighorn and Absaroka basins, which were derived from distal source (>500 km) areas in the Sevier Highlands of Idaho and the Laramide Beartooth and Tobacco Root uplifts. Why the Bighorn Mountains shed abundant Eocene strata only to the east and not to the west remains enigmatic, and merits further study.

Detrital zircon geochronology and provenance of Devono-Mississippian strata in the northern Canadian Cordilleran miogeoclineThis article is one of a series of papers published in this Special Issue on the theme of Geochronology in honour of Tom Krogh.Northwest Territories Geoscience Office Contribution 0047. Geological Survey of Canada Contribution 20100432.

2011 ◽  
Vol 48 (2) ◽  
pp. 515-541 ◽  
Author(s):  
Yvon Lemieux ◽  
Thomas Hadlari ◽  
Antonio Simonetti
Keyword(s):  
Detrital Zircon ◽  
Inductively Coupled Plasma ◽  
Source Region ◽  
Upper Devonian ◽  
Detrital Zircons ◽  
Detrital Zircon Geochronology ◽  
Inductively Coupled ◽  
Arctic Alaska ◽  
Wide Range ◽  
Late Neoproterozoic

U–Pb ages have been determined on detrital zircons from the Upper Devonian Imperial Formation and Upper Devonian – Lower Carboniferous Tuttle Formation of the northern Canadian Cordilleran miogeocline using laser ablation – multicollector – inductively coupled plasma – mass spectrometry. The results provide insights into mid-Paleozoic sediment dispersal in, and paleogeography of, the northern Canadian Cordillera. The Imperial Formation yielded a wide range of detrital zircon dates; one sample yielded dominant peaks at 1130, 1660, and 1860 Ma, with smaller mid-Paleozoic (∼430 Ma), Neoproterozoic, and Archean populations. The easternmost Imperial Formation sample yielded predominantly late Neoproterozoic – Cambrian zircons between 500 and 700 Ma, with lesser Mesoproterozoic and older populations. The age spectra suggest that the samples were largely derived from an extensive region of northwestern Laurentia, including the Canadian Shield, igneous and sedimentary provinces of Canada’s Arctic Islands, and possibly the northern Yukon. The presence of late Neoproterozoic – Cambrian zircon, absent from the Laurentian magmatic record, indicate that a number of grains were likely derived from an exotic source region, possibly including Baltica, Siberia, or Arctic Alaska – Chukotka. In contrast, zircon grains from the Tuttle Formation show a well-defined middle Paleoproterozoic population with dominant relative probability peaks between 1850 and 1950 Ma. Additional populations in the Tuttle Formation are mid-Paleozoic (∼430 Ma), Mesoproterozoic (1000–1600 Ma), and earlier Paleoproterozoic and Archean ages (>2000 Ma). These data lend support to the hypothesis that the influx of sediments of northerly derivation that supplied the northern miogeocline in Late Devonian time underwent an abrupt shift to a source of predominantly Laurentian affinity by the Mississippian.

scholarly journals Detrital Zircon U-Pb-Hf Isotopes of Middle Neoproterozoic Sedimentary Rocks in the Altyn Tagh Orogen, Southeastern Tarim: Insights for a Tarim-South China-North India Connection in the Periphery of Rodinia

Lithosphere ◽  
2020 ◽  
Vol 2020 (1) ◽  
pp. 1-10
Author(s):  
Qian Liu ◽  
Guochun Zhao ◽  
Jianhua Li ◽  
Jinlong Yao ◽  
Yigui Han ◽  
...  
Keyword(s):  
South China ◽  
Detrital Zircon ◽  
Sedimentary Rocks ◽  
Detrital Zircons ◽  
North India ◽  
Hf Isotopes ◽  
Altyn Tagh ◽  
Tarim Craton ◽  
Rodinia Supercontinent ◽  
New Perspective

Abstract The location of the Tarim craton during the assembly and breakup of the Rodinia supercontinent remains enigmatic, with some models advocating a Tarim-Australia connection and others a location at the heart of the unified Rodinia supercontinent between Australia and Laurentia. In this study, our new zircon U-Pb dating results suggest that middle Neoproterozoic sedimentary rocks in the Altyn Tagh orogen of the southeastern Tarim craton were deposited between ca. 880 and 760 Ma in a rifting-related setting slightly prior to the breakup of Rodinia at ca. 750 Ma. A compilation of existing Neoproterozoic geological records also indicates that the Altyn Tagh orogen of the southeastern Tarim craton underwent collision at ca. 1.0-0.9 Ga and rifting at ca. 850-600 Ma related to the assembly and breakup of Rodinia. Furthermore, in order to establish the paleoposition of the Tarim craton with respect to Rodinia, available detrital zircon U-Pb ages and Hf isotopes from Meso- to Neoproterozoic sedimentary rocks were compiled. Comparable detrital zircon ages (at ca. 0.9, 1.3-1.1, and 1.7 Ga) and Hf isotopes indicate a close linkage among rocks of the southeastern Tarim craton, Cathaysia, and North India but exclude a northern or western Australian affinity. In addition, detrital zircons from the northern Tarim craton exhibit a prominent age peak at ca. 830 Ma with minor spectra at ca. 1.9 and 2.5 Ga but lack Mesoproterozoic ages, comparable to the northern and western Yangtze block. Together with comparable geological responses to the assembly and breakup of the Rodinia supercontinent, we offer a new perspective of the location of the Tarim craton between South China and North India in the periphery of Rodinia.

scholarly journals Amazonian Mesoproterozoic basement in the core of the Ibero-Armorican Arc: 40Ar/39Ar detrital mica ages complement the zircon's tale

Geology ◽  
2005 ◽  
Vol 33 (8) ◽  
pp. 637-640 ◽  
Author(s):  
G. Gutiérrez-Alonso ◽  
J. Fernández-Suárez ◽  
Alan S. Collins ◽  
I. Abad ◽  
F. Nieto
Keyword(s):  
Detrital Zircon ◽  
Sedimentary Rocks ◽  
Age Groups ◽  
Strike Slip ◽  
Zircon Age ◽  
Provenance Studies ◽  
The Core ◽  
Pan African ◽  
Rio Negro ◽  
Northwest Iberia

Abstract The 40Ar/39Ar age data on single detrital muscovite grains complement U-Pb zircon ages in provenance studies, as micas are mostly derived from proximal sources and record low-temperature processes. Ediacaran and Cambrian sedimentary rocks from northwest Iberia contain unmetamorphosed detrital micas whose 40Ar/39Ar age spectra suggest an Amazonian–Middle American provenance. The Ediacaran sample contained only Neoproterozoic micas (590–783 Ma), whereas the Cambrian sample contained three age groups: Neoproterozoic (550–640 Ma, Avalonian–Cadomian–Pan African), Mesoproterozoic- Neoproterozoic boundary (ca. 920–1060 Ma, Grenvillian-Sunsas), and late Paleoproterozoic (ca. 1580–1780 Ma, Rio Negro). Comparison of 40Ar/39Ar muscovite ages with published detrital zircon age data from the same formations supports the hypothesis that the Neoproterozoic basins of northwest Iberia were located in a peri-Amazonian realm, where the sedimentary input was dominated by local periarc sources. Tectonic slivering and strike-slip transport along the northern Gondwanan margin affected both the basins and fragments of basement that were transferred from Amazonian to northern African realms during the latest Neoproterozoic–earliest Cambrian. Exhumation and erosion of these basement sources caused shedding of detritus to the Cambrian basins, in addition to detritus sourced in the continental mainland. The apparent dominance of Rio Negro–aged micas in the Cambrian sandstone suggests the presence of unexposed basement of that age beneath the core of the Ibero-Armorican Arc.

Detrital zircon populations of the eastern Laurentian margin in the Appalachians

Geology ◽  
2020 ◽  
Author(s):  
Yvette D. Kuiper ◽  
Christopher Hepburn
Keyword(s):  
United States ◽  
Detrital Zircon ◽  
Orogenic Belt ◽  
Grenville Province ◽  
Zircon Age ◽  
Zircon Population ◽  
Middle Ordovician ◽  
Archean Crust ◽  
Laurentian Margin

Newly compiled U-Pb detrital zircon data from eight geographic domains along the eastern Laurentian margin from Newfoundland (Canada) to Alabama (United States) show a highly consistent signature along strike, with only minor local variations. The Precambrian signature is characterized by a small ca. 2.7 Ga population and a major ca. 1.9–0.9 Ga population that peaks at ca. 1.2–1.0 Ga. Detrital zircon populations are from Laurentian Archean crust (ca. 2.7 Ga population), Paleoproterozoic orogens (ca. 1.9–1.6 Ga), the Granite-Rhyolite Province (ca. 1.5–1.4 Ga), and the Elzevir terrane and Grenville Province (ca. 1.3–0.9 Ga). The Mesoproterozoic populations vary in size depending on proximity to the ca. 1.5–1.4 Ga Granite-Rhyolite Province, the ca. 1245–1225 Ma Elzevir terrane, and the ca. 1.2–0.9 Ga Grenville Province. A middle Ordovician zircon population varies in size along strike depending on input from the Taconic orogenic belt, but it is strongest in the northern Appalachians. Because of the general along-strike consistency in detrital zircon age populations, the compilation of all 7534 concordant U-Pb detrital zircon data can be used in future U-Pb detrital zircon studies as an indicator for eastern Laurentian margin sources.

The Occurrence and Origin of Pentlandite-Chalcopyrite-Pyrrhotite Loop Textures in Magmatic Ni-Cu Sulfide Ores

2020 ◽  
Vol 115 (8) ◽  
pp. 1777-1798 ◽  
Author(s):  
Stephen J. Barnes ◽  
Valentina Taranovic ◽  
Louise E. Schoneveld ◽  
Eduardo T. Mansur ◽  
Margaux Le Vaillant ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Peritectic Reaction ◽  
Inductively Coupled Plasma ◽  
Mass Spectrometry Analysis ◽  
Sulfide Liquid ◽  
Monosulfide Solid Solution ◽  
Spectrometry Analysis ◽  
Inductively Coupled ◽  
Regional Deformation ◽  
Wide Range

Abstract Pentlandite is the dominant Ni-hosting ore mineral in most magmatic sulfide deposits and has conventionally been interpreted as being entirely generated by solid-state exsolution from the high-temperature monosulfide solid solution (MSS) (Fe,Ni)1–xS. This process gives rise to the development of loops of pentlandite surrounding pyrrhotite grains. Recently it has been recognized that not all pentlandite forms by exsolution. Some may form as the result of peritectic reaction between early formed MSS and residual Ni-Cu–rich sulfide liquid during differentiation of the sulfide melt, such that at least some loop textures may be genuinely magmatic in origin. Testing this hypothesis involved microbeam X-ray fluorescence mapping to image pentlandite-pyrrhotite-chalcopyrite intergrowths from a range of different deposits. These deposits exemplify slowly cooled magmatic environments (Nova, Western Australia; Sudbury, Canada), globular ores from shallow-level intrusions (Norilsk, Siberia), extrusive komatiite-hosted ores from low and high metamorphic-grade terranes, and a number of other deposits. Our approach was complemented by laser ablation-inductively coupled plasma-mass spectrometry analysis of palladium in varying textural types of pentlandite within these deposits. Pentlandite forming coarse granular aggregates, together with loop-textured pentlandite where chalcopyrite also forms part of the loop framework, consistently has the highest Pd content compared with pentlandite clearly exsolved as lamellae from MSS or pyrrhotite. This is consistent with much of granular and loop pentlandite being formed by peritectic reaction between Pd-rich residual sulfide liquid and early crystallized MSS, rather than forming entirely by subsolidus grain boundary exsolution from MSS, as has hitherto been assumed. The wide range of Pd contents in pentlandite in individual samples reflects a continuum of processes between peritectic reaction and grain boundary exsolution. Textures in metamorphically recrystallized ores are distinctly different from loop-textured ores, implying that loop textures cannot be regenerated (except in special circumstances) by metamorphic recrystallization of original magmatic-textured ores. The presence of loop textures can therefore be taken as evidence of a lack of penetrative deformation and remobilization at submagmatic temperatures, a conclusion of particular significance to the interpretation of the Nova deposit as having formed synchronously with the peak of regional deformation at temperatures within the sulfide melting range.

Evaluation of Trace Elements in Potatoes (Solanum tuberosum) from a Suburban Area of Naples, Italy: The “Triangle of Death”

2017 ◽  
Vol 80 (7) ◽  
pp. 1167-1171 ◽  
Author(s):  
Antonella De Roma ◽  
Maria Cesarina Abete ◽  
Paola Brizio ◽  
Giuseppe Picazio ◽  
Marcello Caiazzo ◽  
...  
Keyword(s):  
Trace Elements ◽  
Inductively Coupled Plasma ◽  
Climatic Factors ◽  
Suburban Area ◽  
Mass Spectrometry Analysis ◽  
World Health ◽  
Health Concern ◽  
Campania Region ◽  
Spectrometry Analysis ◽  
Health Organization

ABSTRACT Human exposure to contaminated food is a general health concern worldwide; it is necessary to evaluate food safety with respect to contaminants present in the edible parts of major food crops. This study evaluated the concentrations of 17 trace elements (As, Be, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Sb, Se, Sn, Tl, V, and Zn) from 51 potato plantations in the Campania region, inside the area known as the “Triangle of Death,” with inductively coupled plasma mass spectrometry analysis. Results confirm that the potatoes collected from the suburban area of Naples contained concentrations of trace elements below the safe limits prescribed by the Food and Agriculture Organization of the United Nations and the World Health Organization. The concentrations of elements were similar to those reported for potatoes grown in other countries. Monitoring the content of toxic and potentially toxic elements is one of the most important aspects of food quality assurance. The environmental persistence of metals may result in the accumulation of significant levels of these contaminants in plants. They are absorbed to different extents, depending on their source, soil and climatic factors, plant genotype, and agrotechnical conditions, thereby entering the food chain and representing a risk to human health.

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