scholarly journals A consideration on the relation between the rock types of acid igneous rocks and their initial Sr isotopic ratios.

1976 ◽  
Vol 82 (10) ◽  
pp. 655-660 ◽  
Author(s):  
HIROO KAGAMI ◽  
KENJI SHUTO ◽  
MASAO GORAI
Keyword(s):  
Igneous Rocks ◽  
Isotopic Ratios ◽  
Rock Types

scholarly journals Calcium isotopic evidence for the mantle sources of carbonatites

2020 ◽  
Vol 6 (23) ◽  
pp. eaba3269 ◽  
Author(s):  
Elsa Amsellem ◽  
Frédéric Moynier ◽  
Hervé Bertrand ◽  
Amaury Bouyon ◽  
João Mata ◽  
...  
Keyword(s):  
Mantle Source ◽  
Igneous Rocks ◽  
Isotopic Ratios ◽  
Carbonate Minerals ◽  
Isotopic Evidence ◽  
Calcium Isotopes ◽  
Mantle Sources ◽  
Marine Carbonates ◽  
Carbonate Materials ◽  
Silicate Rocks

The origin of carbonatites—igneous rocks with more than 50% of carbonate minerals—and whether they originate from a primary mantle source or from recycling of surface materials are still debated. Calcium isotopes have the potential to resolve the origin of carbonatites, since marine carbonates are enriched in the lighter isotopes of Ca compared to the mantle. Here, we report the Ca isotopic compositions for 74 carbonatites and associated silicate rocks from continental and oceanic settings, spanning from 3 billion years ago to the present day, together with O and C isotopic ratios for 37 samples. Calcium-, Mg-, and Fe-rich carbonatites have isotopically lighter Ca than mantle-derived rocks such as basalts and fall within the range of isotopically light Ca from ancient marine carbonates. This signature reflects the composition of the source, which is isotopically light and is consistent with recycling of surface carbonate materials into the mantle.

Provenance of Mesozoic and Cenozoic sediments from the Labrador and western Greenland continental margins

1978 ◽  
Vol 15 (11) ◽  
pp. 1850-1860 ◽  
Author(s):  
Roger Higgs
Keyword(s):  
Amphibolite Facies ◽  
Igneous Rocks ◽  
Continental Margins ◽  
Low Grade ◽  
Baffin Island ◽  
Source Areas ◽  
Rock Types ◽  
Local Abundance ◽  
Principal Source ◽  
Cenozoic Sediments

Forty-two Cretaceous and Paleocene sand samples from offshore Labrador and onshore western Greenland were examined petrographically. The sands were found to be mineralogically and texturally immature, reflecting rapid erosion and transportation from local, high-relief source areas. The principal source-rock types were acidic plutonics and amphibolite-facies metasediments and metavolcanics. Basic igneous rocks provided minor quantities of detritus, whereas contributions from sedimentary and low-grade-metamorphic sources were negligible. Cretaceous and Paleocene sediment transport was essentially perpendicular to the axis of the 'Labrador–Baffin rift system.In view of the apparent local abundance of amphibolite-facies supracrustal rocks during the Cretaceous and Paleocene, extensive post-Paleocene denudation in Labrador, Baffin Island, and western Greenland is invoked to account for the present scarcity of such rock types.

The Contaminated Gabbro of Easter Saphook near Old Meldrum in Aberdeenshire

1921 ◽  
Vol 58 (4) ◽  
pp. 177-183 ◽  
Author(s):  
H. H. Read
Keyword(s):  
Igneous Rocks ◽  
Geological Survey ◽  
North East ◽  
Rock Types

In North-East Scotland the igneous rocks have been divided into two series, whose times of intrusion were separated by the movements responsible for the foliation and disposition of the crystalline schists of that area.2 With the older series, intruded prior to or during those movements, this paper is not concerned. The younger, or non-foliated, series supplies rock types ranging from peridotite to granite. Gabbro is the chief rock in the large independent basic masses formed by the younger igneous rocks; to the more important of these masses may be given the names of the Huntly, Insch, Boganloch, Haddo, Arnage, Maud, and Belhelvie Masses. For the most part they lie within Sheets 76, 77, 86, and 87 of the 1 inch Geological Survey Map of Scotland.

scholarly journals Pétrographie characterization of rocks from the Mirabello bay region, Crete, and its application to Minoan archaeology: the provenance of stone implements from Minoan sites

2007 ◽  
Vol 40 (4) ◽  
pp. 1768 ◽  
Author(s):  
H. M. Dierckx ◽  
B. Tsikouras
Keyword(s):  
Raw Materials ◽  
Igneous Rocks ◽  
Metamorphic Rocks ◽  
Rock Samples ◽  
Rock Types ◽  
Source Regions ◽  
Time Period

The Minoans of East Crete used a variety of igneous and metamorphic rocks as stone implements. These were probably procured in dry riverbeds and beaches located in a region along the Bay of Mirabello or from an onlap conglomerate, which geologically dominates that region and contains rock types of igneous, metamorphic and sedimentary origin. Several rock samples were collected for pétrographie investigation to examine and confirm the source for the igneous rocks. Detailed pétrographie description of natural samples provides the identification of the rocks employed by Minoans and confirms the source of their origin. Apparently the Minoans were able to evaluate the hardness of the stones procured according to the desirable usage and their expected fatigue, thus avoiding unnecessary timeconsuming treatment. The identification of the variable lithotypes used for these implements and the verification of their source regions reveal the time it took to procure the raw materials as well as the time period during which the rocks were employed.

scholarly journals Rock Types Classification and Distribution on Anabanua Village, Barru Regency, South Sulawesi

2020 ◽  
Vol 8 (1) ◽  
pp. 1-8
Author(s):  
Muhammad Resky Ariansyah ◽  
Muhammad Fawzy Ismullah Massinai ◽  
Muhammad Altin Massinai
Keyword(s):  
Sedimentary Rocks ◽  
Research Area ◽  
Igneous Rocks ◽  
The Other ◽  
Metamorphic Rocks ◽  
Geological Process ◽  
Rock Types ◽  
South Sulawesi ◽  
Geological Conditions ◽  
Limestone Sand

Anabanua Village, Barru Regency is one of the areas in South Sulawesi that has quite unique geological conditions. This condition inseparably comes from the complicated geological process that took place during the formation of the island, Sulawesi. In Anabanua Village, there are many types of rocks such as sedimentary rocks, metamorphic rocks and igneous rocks. This paper aims to map and classify the types of rock by taking samples on different places in the research area. Then we observe the samples physical properties. The results showed, from taking 10 rock samples in different places, they have various characteristics. 8 of them were sedimentary rocks, they are Limestone Quartz, Limestone Sand, Shale, Sandstone, Coal, Limestone Bioturbation, Breccia, and Chert Stone. The other 2 samples were metamorphic rocks, they are Greenschist and Quartzite.

A study of the isotopic abundance of boron from various sources

1968 ◽  
Vol 5 (4) ◽  
pp. 921-927 ◽  
Author(s):  
E. K. Agyei ◽  
C. C. McMullen
Keyword(s):  
Boric Acid ◽  
Atomic Weight ◽  
Igneous Rocks ◽  
Tokyo Bay ◽  
Standard Errors ◽  
Isotopic Ratios ◽  
Isotopic Abundance ◽  
A Value ◽  
The Mean ◽  
The Absolute

The absolute ratio of 11B/10B has been determined for boron from different terrestrial sources with a precision of 0.2% (two standard errors) and a reproducibility of 0.2% (half-range). Values fall in the range 4.108 to 3.987 (i.e. 3% variation) and give a corresponding range in the boron atomic weight of 10.814 to 10.810 (0.04% variation). The absolute ratios are 7% lower than those reported by early workers, but are in accord with the results of recent investigations. Igneous rocks and boric acid are found to have high isotopic ratios, whereas Tokyo Bay water possesses a value for 11B/10B near the mean.

Lead isotopic fingerprinting of tectono-stratigraphic terranes, east-central Alaska

1987 ◽  
Vol 24 (10) ◽  
pp. 2089-2098 ◽  
Author(s):  
John N. Aleinikoff ◽  
Cynthia Dusel-Bacon ◽  
Helen L. Foster ◽  
Warren J. Nokleberg
Keyword(s):  
Isotopic Composition ◽  
Igneous Rocks ◽  
Isotopic Ratios ◽  
East Central ◽  
Isotopic Compositions ◽  
Common Lead ◽  
Crustal Origin ◽  
Lead Isotopic Ratios ◽  
Isotopic Fingerprinting

Common lead isotopic compositions have been determined on feldspars from meta-igneous rocks from nine tectono-stratigraphic terranes or subterranes in east-central Alaska. Most of the terranes have distinct and well-defined signatures in terms of isotopic composition; thus, most can be distinguished on conventional lead isotopic diagrams. Lead isotopic ratios provide evidence for (1) possible sources for the igneous rocks, (2) time of metamorphism, (3) correlation of terrane fragments, and (4) delineation of juxtaposed terranes. Determination of lead isotopic ratios from igneous rocks can be useful in characterizing tectono-stratigraphic terranes (as to mantle or crustal origin) and in correlation, particularly where terrane relationships are enigmatic.

VIII.—Density Measurements of Rocks in South-west Scotland

1961 ◽  
Vol 68 (2) ◽  
pp. 103-111 ◽  
Author(s):  
Adam C. McLean
Keyword(s):  
Geological Structure ◽  
Igneous Rocks ◽  
Density Measurements ◽  
Red Sandstone ◽  
Rock Density ◽  
Topographic Features ◽  
Rock Types ◽  
Gravity Measurements ◽  
Lower Palaeozoic ◽  
Geological Formations

SynopsisA large number of density measurements of the more important rock-types exposed at the surface in Ayrshire and certain neighbouring areas provide information for the interpretation of gravity measurements. The three methods employed of determining density are (1) laboratory measurements of rock samples, (2) gravimeter measurements in mineshafts, and (3) gravimeter measurements over topographic features.The first method, the most widely used, is the only one applicable to many of the geological formations. A total of 600 specimens measured cover all the common rock types of the Lower and Upper Palaeozoic systems and their associated igneous rocks. Use of the second method is restricted to Carboniferous rocks, in which records from four mine-shafts—Littlemill 5, Mauchline I, Auchincruive I, and Houldsworth—cover much of the Carboniferous succession in south Ayrshire. The third method was seldom applied as there are few suitable topographic features, independent of geological structure, in Ayrshire.The results of the measurements are summarized, and their reliability discussed. Two contrasts of rock density of regional importance occur in the sedimentary succession of south Ayrshire—the first at the plane of unconformity between Upper and Lower Old Red Sandstone, and the second between Lower Old Red Sandstone and the Lower Palaeozoic greywackes. A marked contrast of local importance occurs between the Permian sandstones of the Mauchline Basin and the underlying lavas and Carboniferous rocks. In north Ayrshire the most important density contrast lies between the Upper Palaeozoic sediments and the associated dense igneous rocks—the Clyde Plateau Lavas, the Millstone Grit lavas, and the thick dolerite intrusions.

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