scholarly journals Supplemental Material: Retroarc Jurassic burial and exhumation of Barrovian metamorphic rocks dated by monazite petrochronology, Funeral Mountains, California

2021 ◽  
Author(s):  
Suzanne Craddock Affinati ◽  
et al.
Keyword(s):  
Metamorphic Rocks ◽  
Isotopic Data ◽  
Element Abundances ◽  
Elemental Data

All isotope and elemental data collected and presented in this paper. Table S1 includes monazite isotopic data for U-Th-Pb, element abundances, calculated chondrite normalized REE values, and calculated ages. Table S2 includes xenotime isotopic data for U-Th-Pb, element abundances, calculated chondrite normalized REE values, and calculated ages. Table S3 includes garnet element abundances and chondrite normalized REE data collected along rim-to-rim line traverses.<br>

scholarly journals Supplemental Material: Retroarc Jurassic burial and exhumation of Barrovian metamorphic rocks dated by monazite petrochronology, Funeral Mountains, California

2021 ◽  
Author(s):  
Suzanne Craddock Affinati ◽  
et al.
Keyword(s):  
Metamorphic Rocks ◽  
Isotopic Data ◽  
Element Abundances ◽  
Elemental Data

All isotope and elemental data collected and presented in this paper. Table S1 includes monazite isotopic data for U-Th-Pb, element abundances, calculated chondrite normalized REE values, and calculated ages. Table S2 includes xenotime isotopic data for U-Th-Pb, element abundances, calculated chondrite normalized REE values, and calculated ages. Table S3 includes garnet element abundances and chondrite normalized REE data collected along rim-to-rim line traverses.<br>

scholarly journals A unique basaltic micrometeorite expands the inventory of solar system planetary crusts

2009 ◽  
Vol 106 (17) ◽  
pp. 6904-6909 ◽  
Author(s):  
Matthieu Gounelle ◽  
Marc Chaussidon ◽  
Alessandro Morbidelli ◽  
Jean-Alix Barrat ◽  
Cécile Engrand ◽  
...  
Keyword(s):  
Solar System ◽  
Mineral Chemistry ◽  
Carbonaceous Chondrites ◽  
Isotopic Data ◽  
Solar System Formation ◽  
Sample Return ◽  
Dust Transport ◽  
Element Abundances ◽  
Transport Dynamics ◽  
Sample Return Mission

Micrometeorites with diameter ≈100–200 μm dominate the flux of extraterrestrial matter on Earth. The vast majority of micrometeorites are chemically, mineralogically, and isotopically related to carbonaceous chondrites, which amount to only 2.5% of meteorite falls. Here, we report the discovery of the first basaltic micrometeorite (MM40). This micrometeorite is unlike any other basalt known in the solar system as revealed by isotopic data, mineral chemistry, and trace element abundances. The discovery of a new basaltic asteroidal surface expands the solar system inventory of planetary crusts and underlines the importance of micrometeorites for sampling the asteroids' surfaces in a way complementary to meteorites, mainly because they do not suffer dynamical biases as meteorites do. The parent asteroid of MM40 has undergone extensive metamorphism, which ended no earlier than 7.9 Myr after solar system formation. Numerical simulations of dust transport dynamics suggest that MM40 might originate from one of the recently discovered basaltic asteroids that are not members of the Vesta family. The ability to retrieve such a wealth of information from this tiny (a few micrograms) sample is auspicious some years before the launch of a Mars sample return mission.

Nd isotopic characteristics of metamorphic and plutonic rocks of the Coast Mountains near Prince Rupert, British Columbia

1998 ◽  
Vol 35 (5) ◽  
pp. 556-561 ◽  
Author(s):  
P J Patchett ◽  
G E Gehrels ◽  
C E Isachsen
Keyword(s):  
British Columbia ◽  
Volcanic Rocks ◽  
Metamorphic Rocks ◽  
Published Data ◽  
Isotopic Data ◽  
Crustal Component ◽  
Coast Mountains ◽  
Crustal Rocks ◽  
Metasedimentary Rocks ◽  
Plutonic Rocks

Nd isotopic data are presented for a suite of metamorphic and plutonic rocks from a traverse across the Coast Mountains between Terrace and Prince Rupert, British Columbia, and for three contrasting batholiths in the Omineca Belt of southern Yukon. A presumed metamorphic equivalent of Jurassic volcanic rocks of the Stikine terrane gives epsilon Nd = +6, and a number of other metaigneous and metasedimentary rocks in the core of the Coast Mountains give epsilon Nd values from +3 to +7. A single metasedimentary rock approximately 3 km east of the Work Channel shear zone gives a epsilon Nd value of -9. Coast Belt plutons in the traverse yield epsilon Nd from -1 to +2. The Omineca Belt plutons give epsilon Nd from -10 to -17. All results are consistent with published data in demonstrating that (i) juvenile origins for both igneous and metamorphic rocks are common in the Coast Belt; (ii) representatives of a continental-margin sedimentary sequence with Precambrian crustal Nd are tectonically interleaved in the Coast Mountains; (iii) Coast Mountains plutons can be interpreted as derived from a blend of metamorphic rocks like those seen at the surface, or as arc-type melts contaminated with the older crustal component; and (iv) Omineca Belt plutons are dominated by remelted Precambrian crustal rocks.

I. Ultramafic rocks - Peridotite—gabbro—basalt complex from the equatorial Mid-Atlantic Ridge

1971 ◽  
Vol 268 (1192) ◽  
pp. 385-402 ◽  
Keyword(s):  
Upper Mantle ◽  
Early Stage ◽  
Ultramafic Rocks ◽  
Metamorphic Rocks ◽  
Fracture Zones ◽  
Equatorial Atlantic ◽  
Isotopic Data ◽  
The World ◽  
Mid Atlantic Ridge ◽  
Liquid Fractionation

Rocks were dredged where the Mid-Atlantic Ridge is intersected by the Chain, Romanche, St Paul and Vema Fracture Zones, and from unfractured portions of the Ridge between 6 and 8° N. Peridotites are common at the fracture zones, but were found also in unfractured sections of the Ridge; harzburgites prevail, but lherzolites, dunites and plagioclase peridotites are also present. A variety of gabbros was recovered, generally above the peridotites, including norites, troctolites, quartz gabbros and theralites. The chemistry of these gabbros indicates a marked crystal-liquid fractionation, following both a ‘tholeiitic’ and an ‘alkali’ trend. The basalts show also both trends, but less markedly. Metamorphic rocks ranging from ‘greenschist’ to ‘amphibolite’ facies are found throughout the sections. Strontium isotopic data suggest that the peridotites (excluding St Peter-Paul rocks) are not related genetically to the associated gabbro-basalt, in a situation similar to that of alpine complexes on the continents. The peridotites are probably residual and were depleted of lithophile elements at some early stage of their history, before the opening of the Atlantic rift. It is postulated that in the upper mantle below the equatorial Atlantic a zone exists of residual, alpine-type peridotite, while the lower crust consists of a mixture of ultramafics and intrusive gabbros. The data indicate strong similarities between the Mid-Atlantic Ridge and alpine complexes from various parts of the world.

The Caldwell Group lavas of southern Quebec: MORB-like tholeiites associated with the opening of Iapetus Ocean

1999 ◽  
Vol 36 (6) ◽  
pp. 999-1019 ◽  
Author(s):  
Jean H Bédard ◽  
Ross Stevenson
Keyword(s):  
Incompatible Element ◽  
Crustal Contamination ◽  
Isotopic Data ◽  
High Field Strength ◽  
Element Abundances ◽  
Incompatible Elements ◽  
Iapetus Ocean ◽  
Mid Ocean Ridge ◽  
Source Mantle ◽  
Ocean Ridge

The Caldwell Group belongs to the Internal Nappe Domain of the Humber Zone and consists of basaltic lavas, quartzo-feldspathic sandstones, and mudslates. The lavas are clinopyroxene ± plagioclase ± olivine-phyric tholeiites, and are typically altered to epidote-, chlorite-, carbonate-, and (or) hematite-rich secondary assemblages. In most cases, the high field strength elements do not appear to have been perturbed by the alteration, and preserve magmatic signatures. Most Caldwell basalts exhibit coupled major and trace element variations compatible with low- to medium-pressure ([Formula: see text] 10 kbar, where 1 kbar = 100 MPa) fractional crystallization. Paleotectonic discriminants imply an ocean-floor or normal mid-ocean ridge basalt (N-MORB) affinity. Most basalts have flat N-MORB-normalized profiles, except for the highly incompatible elements (Ba, Th, Nb), which show slight relative enrichment. Melting models suggest that most of these lavas formed by about 20% melting from a mantle slightly less depleted than fertile MORB mantle (FMM). Subpopulations of Caldwell lavas (types 1b and 1a) are characterized by slightly higher incompatible element abundances, with similarly shaped N-MORB-normalized profiles, and can be modeled by slightly smaller degrees of melting (6-15%) of a similar source mantle. The Caldwell basalts erupted in the final stages of Iapetus rifting, when the predominant mantle source involved in melting was the depleted asthenosphere. Isotopic data preclude significant crustal contamination, yet the basalts are associated with sandstones, implying that a mature continental crust was present nearby. Nd isotopic data on the sandstones suggest erosion of an ancient Archean-Proterozoic composite terrane.

A Natural Analogue for Storage of Radwaste in Crystalline Rocks

1981 ◽  
Vol 6 ◽  
Author(s):  
Douglas G. Brookins ◽  
Mark S. Abashian ◽  
Lewis H. Cohen ◽  
Harold A. Wollenberg
Keyword(s):  
High Heat ◽  
Metamorphic Rocks ◽  
Natural Analogue ◽  
Isotopic Data ◽  
Simple Diffusion ◽  
Flow Models ◽  
Intrusive Rocks ◽  
Porosity And Permeability ◽  
Simple Diffusion Model ◽  
Geochemical Studies

ABSTRACTThe Bryan-Eldora stock (Colorado) intruded the Precambrian Idaho Springs Formation metamorphic rocks 58 million years ago. Geochronologic-geochemical work by Hart et al. (1) has demonstrated that the heat from the cooling intrusive rocks was sufficient to affect mineral isotopic systematics up to 2,000 m. from the contact, and the nature of these isotopic perturbations can be explained by a simple diffusion model in turn based on various heat flow models. Our new studies are focused on elemental exchange between stock and intruded rock as a function of distance from the contact; the assumption is made that the stock is a very large, high heat source analogous to a waste form emplaced in the metamorphic rocks without benefit of canister or engineered backfill. Data for U, Th and the REE indicate actinide and lanthanide immobility except perhaps in the 0–2m. contact zone where some infiltration of the country rocks by stock-derived fluids occurred. Beyond 4 m. no stock-derived U, Th, REE or *Pb are noted. Further, whole rock Rb-Sr and stable 0 isotopic data indicate conductive cooling as opposed to convective, water-induced cooling. The intruded rocks possess low porosity and permeability; this helped prevent elemental migration during the 105 − 106 years of stock crystallization. The petrographic and geochemical studies show that the Idaho Springs (or equivalent) metamorhpic rocks are well suited for radwaste storage.

scholarly journals Carbonatites from the Southern Brazilian platform: I

2020 ◽  
Vol 12 (1) ◽  
pp. 452-478
Author(s):  
Sergio Speziale ◽  
Francesca Castorina ◽  
Paolo Censi ◽  
Celso de Barros Gomes ◽  
Leila Soares Marques ◽  
...  
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Hydrothermal Fluids ◽  
Evolutionary Trend ◽  
Compelling Evidence ◽  
Isotopic Data ◽  
Comprehensive Overview ◽  
Element Abundances ◽  
Compositional Variability ◽  
Formation And Evolution

AbstractWe present a comprehensive overview of the geochemical characteristics and evolution of the carbonatites from the southern Brazilian Platform (Paraná Basin). The carbonatites from different complexes display large compositional variability in terms of abundances of incompatible and rare earth elements. This is in agreement with an origin from heterogeneous lithospheric sources, as confirmed by isotopic data (see Speziale et al., this issue). The characteristic major and trace element abundances of these carbonatites present compelling evidence for invoking liquid unmixing as the main mechanism of their formation and evolution albeit few exceptions. We propose an evolutionary trend for the Brazilian carbonatites, which can be summarized as following: exsolution of the primary Ca- or Mg-carbonatitic liquids systematically takes place at the phonolite-peralkaline phonolite stage of magma differentiation; this is followed by progressive Fe-enrichment and by final emplacement of fluorocarbonatites associated with hydrothermal fluids.

Distribution of R- and S-Process Elements in the Galactic Halo

1988 ◽  
Vol 132 ◽  
pp. 501-506
Author(s):  
C. Sneden ◽  
C. A. Pilachowski ◽  
K. K. Gilroy ◽  
J. J. Cowan
Keyword(s):  
Heavy Element ◽  
Galactic Halo ◽  
Low Noise ◽  
Heavy Elements ◽  
Process Synthesis ◽  
Element Abundances ◽  
Halo Stars ◽  
Abundance Patterns ◽  
R Process ◽  
Process Elements

Current observational results for the abundances of the very heavy elements (Z&gt;30) in Population II halo stars are reviewed. New high resolution, low noise spectra of many of these extremely metal-poor stars reveal general consistency in their overall abundance patterns. Below Galactic metallicities of [Fe/H] Ã −2, all of the very heavy elements were manufactured almost exclusively in r-process synthesis events. However, there is considerable star-to-star scatter in the overall level of very heavy element abundances, indicating the influence of local supernovas on element production in the very early, unmixed Galactic halo. The s-process appears to contribute substantially to stellar abundances only in stars more metal-rich than [Fe/H] Ã −2.

TEM/AEM characterization of fine-grained clay minerals in very-low-grade rocks: Evaluation of contamination by empa involving celadonite family minerals

1996 ◽  
Vol 54 ◽  
pp. 694-695
Author(s):  
Gejing Li ◽  
D. R. Peacor ◽  
D. S. Coombs ◽  
Y. Kawachi
Keyword(s):  
Electron Microscopy ◽  
Volcanic Rocks ◽  
Analytical Electron Microscopy ◽  
Metamorphic Rocks ◽  
New Mineral ◽  
Chemical Compositions ◽  
Low Grade ◽  
Fine Grained ◽  
Depth Analysis ◽  
Mineral Aggregates

Recent advances in transmission electron microscopy (TEM) and analytical electron microscopy (AEM) have led to many new insights into the structural and chemical characteristics of very finegrained, optically homogeneous mineral aggregates in sedimentary and very low-grade metamorphic rocks. Chemical compositions obtained by electron microprobe analysis (EMPA) on such materials have been shown by TEM/AEM to result from beam overlap on contaminant phases on a scale below resolution of EMPA, which in turn can lead to errors in interpretation and determination of formation conditions. Here we present an in-depth analysis of the relation between AEM and EMPA data, which leads also to the definition of new mineral phases, and demonstrate the resolution power of AEM relative to EMPA in investigations of very fine-grained mineral aggregates in sedimentary and very low-grade metamorphic rocks.Celadonite, having end-member composition KMgFe3+Si4O10(OH)2, and with minor substitution of Fe2+ for Mg and Al for Fe3+ on octahedral sites, is a fine-grained mica widespread in volcanic rocks and volcaniclastic sediments which have undergone low-temperature alteration in the oceanic crust and in burial metamorphic sequences.

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