Paleozoic intrusive rocks in the Nalati mountain range (NMR), southwest Tianshan: Geodynamic evolution based on petrology and geochemical studies

Geochronology of the Neogene calc-alkaline intrusive magmatism in the "Subvolcanic Zone" of the Eastern Carpathians (Romania)The Poiana Botizei-Ţibleş-Toroiaga-Rodna-Bârgâu intrusive area (PBTTRB), northwest Romania, known as the "Subvolcanic Zone", is located between the Gutâi (NW) and Câlimani (SE) volcanic massifs. It consists of rocks displaying a wide range of compositions and textures: equigranular or porphyritic with holocrystalline groundmass (gabbro-diorites, diorites, monzodiorites and granodiorites), and/or porphyritic with fine holocrystalline or glassycryptocrystalline groundmass, similar with effusive rocks: basalts, basaltic andesites, andesites, dacites and rhyolites. The time-span of intrusive rocks emplacement is similar with the nearest calc-alkaline volcanic rocks from Gutâi (NW) and Câlimani (SE) massifs. They are represented by stocks, laccoliths, dykes and sills typical for an upper crustal intrusive environment. In the absence of biostratigraphic evidence, a comprehensive K-Ar study of intrusive rocks using whole rock samples, groundmass and monomineral fractions (biotite, hornblende) has been carried out in order to understand the magmatic evolution of the area. The oldest K-Ar ages recorded in the analysed rocks are close to 11.5 Ma and magmatism continued to develop until about 8.0 Ma. The inception of intrusion emplacement in the PBTTRB is coeval with intrusive activity spatially related to volcanism within the neighbouring Gutâi and Câlimani massifs. However, its culmination at ca. 8 Ma ago is younger than the interruption of this activity at ca. 9.2 Ma in Gutâi and Câlimani Mts where intrusive activity resumed for ca. 1 Myr. These circumstances strongly suggest that the geodynamic evolution of the area controlled the development of both volcanic and intrusive activity and their reciprocal relationships. The overall geological data suggest that in the PBTTRB intra-lithospheric transpressional-transtensional tectonic processes controlled the generation and emplacement of intrusive bodies between ca. 12-8 Ma.

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Aborted Proterozoic rifting in eastern Newfoundland

Canadian Journal of Earth Sciences ◽

10.1139/e78-010 ◽

1978 ◽

Vol 15 (1) ◽

pp. 117-131 ◽

Cited By ~ 37

Author(s):

D. F. Strong ◽

S. J. O'Brien ◽

S. W. Taylor ◽

P. G. Strong ◽

D. H. Wilton

Keyword(s):

Source Region ◽

Sedimentary Rocks ◽

Ocean Basin ◽

Geological Mapping ◽

Southwestern Part ◽

Bimodal Volcanism ◽

Intrusive Rocks ◽

Group A ◽

Geochemical Studies ◽

Alkalic Basalts

Recent geological mapping and geochemical studies of the late Proterozoic rocks of the Burin Peninsula in the southwestern part of the Avalon Zone of Newfoundland show the following sequence: (1) The basal Rock Harbour Group, a sedimentary assemblage ranging from conglomerates to turbidites, was derived from a subaerial volcanic–plutonic source region. (2) The overlying Burin Group, a belt of mafic volcanic and intrusive rocks that have alkalic affinities at the base but are dominated by oceanic tholeiite. (3) The Marystown Group, a bimodal sequence of alkalic basalts and rhyolites deposited in a subaerial environment unconformably above the Burin Group, and apparently conformably overlain by Infracambrian to Cambrian sedimentary rocks. Stromatolites occur within resedimented limestone breccias and conglomerates at the top of the Rock Harbour Group and throughout the Burin Group.These assemblages are interpreted to indicate that after a period of continental type bimodal volcanism, the Avalon terrain was rifted in Burin Group times to form some kind of small ocean basin, which was abruptly closed with a reversion to continental type bimodal volcanism of the Marystown Group.

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Microstructural and geochemical studies of Higher Himalayan Leucogranite: implications for geodynamic evolution of Tertiary Leucogranite in the Eastern Himalaya

Geological Journal ◽

10.1002/gj.2480 ◽

2013 ◽

Vol 49 (1) ◽

pp. 28-51 ◽

Cited By ~ 2

Author(s):

R. K. Bikramaditya Singh ◽

A. Krishnakanta Singh

Keyword(s):

Eastern Himalaya ◽

Geodynamic Evolution ◽

Geochemical Studies

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A Natural Analogue for Storage of Radwaste in Crystalline Rocks

MRS Proceedings ◽

10.1557/proc-6-231 ◽

1981 ◽

Vol 6 ◽

Cited By ~ 1

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.

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Permo-Triassic Clastic Rocks from the Ghomaride Complex and Federico Units (Rif Cordillera, N Morocco): An Example of Diagenetic-Metamorphic Transition

Minerals ◽

10.3390/min9120738 ◽

2019 ◽

Vol 9 (12) ◽

pp. 738 ◽

Cited By ~ 2

Author(s):

Mª Dolores Rodríguez-Ruiz ◽

Isabel Abad ◽

María J. Bentabol

Keyword(s):

Regional Metamorphism ◽

Mountain Range ◽

Low Grade ◽

Illite Crystallinity ◽

Geodynamic Evolution ◽

Alpine Orogeny ◽

Clastic Rocks ◽

Wide Range ◽

Mixed Layers

A detailed characterization of the mineralogy corresponding to the low-grade diagenetic-metamorphic sequence of the clastic rocks from the Beni Mezala antiform has allowed the processes implied in their origin to be stablished, integrating them in the geodynamic evolution of the Rif-Betic mountain range during the Alpine orogeny. A progressive evolution towards chemical and textural equilibrium was observed. The illite “crystallinity” (CIS) ranges from diagenetic-lower anchizone in Ghomaride complex (CIS: 1.50–0.37 Δ°2θ) to epizone in the deepest Federico units (CIS: 0.29–0.21 Δ°2θ). The main phyllosilicates in the diagenetic samples are illite (2M1-1M polytypes) and kaolinite, with mixed-layer illite/smectite and chlorite, but the mixed layers disappear in the lower anchizone samples, which show sudoite and dickite. Pyrophyllite is also present in the upper anchizone (0.43–0.29 Δ°2θ) whereas the epizone samples show muscovite (2M1-3T polytypes), chlorite, paragonite, and intermediate micas. The chlorite geothermometers give a T range of 150 to 400 °C, and the b parameter of 2M1 micas (8.992–9.029 Å) indicates low to intermediate pressure regional metamorphism (1–3 kbar) although the wide range of phengitic substitution in micas and the 3T polytype suggest a wider pressure range in coherence with the clockwise PTt evolution for the Rif Cordillera during the Alpine orogeny.

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Results of New Field and Geochemical Studies of the Volcanic and Intrusive Rocks of the Maymecha-Kotuy Area, Siberian Flood-Basalt Province, Russia

International Geology Review ◽

10.1080/00206819709465286 ◽

1997 ◽

Vol 39 (6) ◽

pp. 479-531 ◽

Cited By ~ 73

Author(s):

Valeri Fedorenko ◽

Gerald Czamanske

Keyword(s):

Flood Basalt ◽

Intrusive Rocks ◽

Geochemical Studies

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Introduction to Cell Membranes at Molecular Resolution

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100070217 ◽

1978 ◽

Vol 36 (3) ◽

pp. 497-502

Author(s):

R.J. Barrnett

Keyword(s):

Cell Membranes ◽

International Federation ◽

Mountain Range ◽

Cellular Membranes ◽

Short History ◽

Biological Organization ◽

Macromolecular Assemblies ◽

The Past

This subject, is like observing the panorama of a mountain range, magnificent towering peaks, but it doesn't take much duration of observation to recognize that they are still in the process of formation. The mountains consist of approaches, materials and methods and the rocky substance of information has accumulated to such a degree that I find myself concentrating on the foothills in the foreground in order to keep up with the advance; the edifices behind form a wonderous, substantive background. It's a short history for such an accumulation and much of it has been moved by the members of the societies that make up this International Federation. My panel of speakers are here to provide what we hope is an interesting scientific fare, based on the fact that there is a continuum of biological organization from biochemical molecules through macromolecular assemblies and cellular membranes to the cell itself. Indeed, this fact explains the whole range of towering peaks that have emerged progressively during the past 25 years.

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