Статті в журналах: "Late Precambrian"

1

Zhang, Y. "Interpreting Late Precambrian Microfossils." Science 282, no. 5395 (December 4, 1998): 1783a—1783. http://dx.doi.org/10.1126/science.282.5395.1783a.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

2

Ivantsov, A. Yu, and M. A. Zakrevskaya. "Symmetry of Vendobionta (Late Precambrian Metazoa)." Paleontological Journal 55, no. 7 (December 2021): 717–26. http://dx.doi.org/10.1134/s0031030121070054.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

3

Odin, G. S., N. H. Gale, and F. Doré. "Radiometric dating of Late Precambrian times." Geological Society, London, Memoirs 10, no. 1 (1985): 65–72. http://dx.doi.org/10.1144/gsl.mem.1985.010.01.07.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

4

Valentine, J. W. "Late Precambrian bilaterians: grades and clades." Proceedings of the National Academy of Sciences 91, no. 15 (July 19, 1994): 6751–57. http://dx.doi.org/10.1073/pnas.91.15.6751.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

5

Thorpe, R. S. "Geochemistry and eruptive environment of metavolcanic rocks from the Mona Complex of Anglesey, North Wales, U.K." Geological Magazine 130, no. 1 (January 1993): 85–91. http://dx.doi.org/10.1017/s0016756800023748.

Повний текст джерела

Анотація:

AbstractThe late Precambrian–early Palaeozoic Monian Supergroup of the Mona Complex is a thick sequence of flysch-type sediments and metavolcanic rocks which were deposited during the late Precambrian–early Palaeozoic and deformed during the late Precambrian and Caledonian (Ordovician/Silurian) orogenies. The Monian Supergroup includes tectonically emplaced, geographically separated outcrops of metabasalt/andesite, gabbro and serpentinized ultramafic rocks all of ophiolite affinity. The major units of the Mona Complex are separated by important faults/fault zones which may represent terrane boundaries. New chemical analyses, together with existing ones, show that the metabasalts and meta-andesites from the older New Harbour Group of north Anglesey have characteristics of suprasubduction zone arc eruptives whereas the metabasalts from the younger Gwna Group of south Anglesey and Lleyn have MORB geochemistry. It is suggested that these volcanic rocks were produced during the late Precambrian–early Palaeozoic development of the lapetus Ocean and emplaced as separate terranes during its closure.

Стилі APA, Harvard, Vancouver, ISO та ін.

6

Al-Malabeh, Ahmad, Hasan Al-Fugha, and Tayel El Hasan. "Petrology and geochemistry of Late Precambrian magmatic rocks from southern Jordan." Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen 233, no. 3 (September 1, 2004): 333–50. http://dx.doi.org/10.1127/njgpa/233/2004/333.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

7

Cowie, J. W., and M. R. W. Johnson. "Late Precambrian and Cambrian geological time-scale." Geological Society, London, Memoirs 10, no. 1 (1985): 47–64. http://dx.doi.org/10.1144/gsl.mem.1985.010.01.06.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

8

Knauth, L. Paul, and Martin J. Kennedy. "The late Precambrian greening of the Earth." Nature 460, no. 7256 (July 8, 2009): 728–32. http://dx.doi.org/10.1038/nature08213.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

9

Morris, S. C. "Late Precambrian and Cambrian Soft-Bodied Faunas." Annual Review of Earth and Planetary Sciences 18, no. 1 (May 1990): 101–22. http://dx.doi.org/10.1146/annurev.ea.18.050190.000533.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

10

Bengtson, S., and Y. Zhao. "Predatorial Borings in Late Precambrian Mineralized Exoskeletons." Science 257, no. 5068 (July 17, 1992): 367–69. http://dx.doi.org/10.1126/science.257.5068.367.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

11

Murphy, J. Brendan. "Late Precambrian to Late Devonian mafic magmatism in the Antigonish Highlands of Nova Scotia: multistage melting of a hydrated mantle." Canadian Journal of Earth Sciences 25, no. 4 (April 1, 1988): 473–85. http://dx.doi.org/10.1139/e88-048.

Повний текст джерела

Анотація:

Five suites of alkalic basalt ranging in age from Late Precambrian to Late Devonian are found in the Antigonish Highlands of Nova Scotia. In contrast, on neighbouring Cape Breton Island, alkalic basalts are rare even in suites that are contemporaneous with those in the Antigonish Highlands. Late Precambrian alkalic basalts in the Antigonish Highlands are genetically associated with calc-alkalic rocks and are probably subduction related, whereas the younger suites are continental, rift related, and within plate. Major and compatible trace-element abundances can be explained by crystal fractionation of olivine ± clinopyroxene ± orthopyroxene ± spinel ± garnet. However, incompatible trace-element concentrations are strongly influenced by mantle metasomatism that occurred prior to, or synchronously with, the oldest alkalic rocks. The metasomatic event enriched the mantle in Fe, Ti, P, Zr, and light rare-earth elements. The trace-element composition of the younger suites is similar to that of the oldest alkalic rocks and may have been strongly influenced by the Late Precambrian metasomatic event. The anomalously low Nb/Y ratio (generally less than 1 in all suites) and application of phase-equilibria studies indicate that the metasomatic fluid was probably rich in H2O. This fluid may have been derived from dehydration of the subducting slab in Late Precambrian time, resulting in metasomatism of the overlying mantle wedge in the Late Precambrian. It is proposed that the younger suites obtained their fluids by dehydration of the previously metasomatized mantle associated with the generation of local pull-apart basins. Thus, the metasomatic fluid was exotic with respect to the oldest basalts but indigenous with respect to the younger basalts. In the younger basalts, the indigenous fluid was probably focussed at the site of melting by structural events (i.e., rifting). In situations in which the chemistry of mafic magmas is predetermined by earlier metasomatic events, caution is advised in using trace-element criteria to evaluate the tectonic setting.

Стилі APA, Harvard, Vancouver, ISO та ін.

12

Harper, David A., Fred J. Longstaffe, Moire A. Wadleigh, and Robert H. McNutt. "Secondary K-feldspar at the Precambrian–Paleozoic unconformity, southwestern Ontario." Canadian Journal of Earth Sciences 32, no. 9 (September 1, 1995): 1432–50. http://dx.doi.org/10.1139/e95-116.

Повний текст джерела

Анотація:

The Precambrian–Paleozoic boundary in the subsurface of southwestern Ontario commonly is characterized by secondary K-feldspar. In the weathered and altered Precambrian granitoid gneisses at the unconformity, secondary K-feldspar has replaced preexisting minerals, and also occurs as discrete crystals of adularia, overgrowths on altered minerals, and microcrystalline veinlets. The K-feldspar is chemically pure (Or99–100) and has high δ18O values (+18.9 to +21.4‰ Vienna Standard Mean Ocean Water), features that indicate crystallization at low temperatures. Secondary K-feldspar also occurs in Cambro-Ordovician clastic and carbonate rocks that immediately overlie the Precambrian basement. K/Ar (453 ± 9 to 412 ± 8 Ma) and Rb/Sr (440 ± 50 Ma) dates obtained for secondary K-feldspar from the Precambrian host rocks suggest that its crystallization is unrelated to Precambrian weathering or early diagenesis of the immediately overlying Cambro-Ordovician strata. Estimated crystallization temperatures for the secondary K-feldspar (≥100 °C) exceed presumed burial temperatures for the Precambrian–Paleozoic boundary in southwestern Ontario during Late Ordovician–Silurian time. We infer that secondary K-feldspar formed from a hot brine that moved preferentially along the Precambrian–Paleozoic unconformity. The wide distribution of secondary K-feldspar of Late Ordovician–Silurian age throughout mid-continental North America at the Precambrian–Paleozoic boundary records the regional extent of this process. Some Cambro-Ordovician rocks elsewhere in the mid-continent also contain secondary K-feldspar and illitic clay of Late Pennsylvanian–Early Permian age, suggesting more than one episode of fluid movement. Major pulses of orogenic activity may have initiated brine migration. We speculate that the brine originated as connate (sea) water trapped in lower Paleozoic strata, and was modified by rock–water interaction at elevated temperatures, and by mixing with meteoric water.

Стилі APA, Harvard, Vancouver, ISO та ін.

13

Ivantsov, A. Yu. "The most probable Eumetazoa among late Precambrian macrofossils." Invertebrate Zoology 14, no. 1 (August 2017): 127–33. http://dx.doi.org/10.15298/invertzool.14.2.05.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

14

Magee, A. W., and S. J. Culver. "Recognition of late Precambrian glaciogenic sediments in Liberia." Geology 14, no. 11 (1986): 920. http://dx.doi.org/10.1130/0091-7613(1986)14<920:rolpgs>2.0.co;2.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

15

Liang Yuzuo, Zhu Shixing, Zhang Luyi, Cao Renguan, Gao Zhenjia, and Bu De'An. "Stromatolite assemblages of the late precambrian in China." Precambrian Research 29, no. 1-3 (June 1985): 15–32. http://dx.doi.org/10.1016/0301-9268(85)90056-7.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

16

STRACHAN, R. A., R. D. NANCE, R. D. DALLMEYER, R. S. D'LEMOS, J. B. MURPHY, and G. R. WATT. "Late Precambrian tectonothermal evolution of the Malverns Complex." Journal of the Geological Society 153, no. 4 (July 1996): 589–600. http://dx.doi.org/10.1144/gsjgs.153.4.0589.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

17

Veizer, Ján, K. A. Plumb, R. N. Clayton, R. W. Hinton, and J. P. Grotzinger. "Geochemistry of Precambrian carbonates: V. Late Paleoproterozoic seawater." Geochimica et Cosmochimica Acta 56, no. 6 (June 1992): 2487–501. http://dx.doi.org/10.1016/0016-7037(92)90204-v.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

18

Klincharov, Sokol, and Vasil Anastasovski. "Markovi kouli (Macedonia) – protected geological site." Geologica Balcanica 26, no. 2 (June 30, 1996): 25–27. http://dx.doi.org/10.52321/geolbalc.26.2.25.

Повний текст джерела

Анотація:

The locality Markovi kouli near the town of Prilep is a complex site of geological, botanical, archaeological, historical and cultural significance. It consists of Precambrian metamorphic rocks (gneiss and schists) intruded by Late Precambrian granodiorite. Erosion led to formation of beautiful landforms. Endemic plants species, fortress and monasteries add to the importance of thet remarkable complex site.

Стилі APA, Harvard, Vancouver, ISO та ін.

19

Lin, Shoufa. "Relationship between the Aspy and Bras d'Or "terranes" in the northeastern Cape Breton Highlands, Nova Scotia." Canadian Journal of Earth Sciences 30, no. 9 (September 1, 1993): 1773–81. http://dx.doi.org/10.1139/e93-157.

Повний текст джерела

Анотація:

According to previous interpretations, the Eastern Highlands shear zone separates Ordovician–Silurian volcano-sedimentary rocks to the west (Cheticamp Lake Gneiss of the Aspy "terrane") from late Precambrian sedimentary rocks and dioritic – tonalitic plutons and Early Ordovician granite to the east (Bras d'Or "terrane"). New mapping discovered a basal conglomerate of the Cheticamp Lake Gneiss that rests on deformed diorite of the Bras d'Or "terrane" and contains clasts similar or identical to rocks of the Bras d'Or "terrane." The late Precambrian rocks of the Bras d'Or "terrane" are also overlain by a volcano-sedimentary sequence of Silurian age (Clyburn Brook formation). These observations suggest that rocks of the Aspy "terrane" lie unconformably on those of the Bras d'Or "terrane." The Eastern Highlands shear zone is therefore not a terrane boundary. The Ordovician–Silurian rocks of the Aspy "terrane" are interpreted to have formed in an arc–back-arc basin system. The back-arc basin is interpreted to have formed by rifting in the Bras d'Or "terrane" and the Eastern Highlands shear zone to have been related to the closure of the basin.

Стилі APA, Harvard, Vancouver, ISO та ін.

20

Carver, J. H., and I. M. Vardavas. "Precambrian glaciations and the evolution of the atmosphere." Annales Geophysicae 12, no. 7 (June 30, 1994): 674–82. http://dx.doi.org/10.1007/s00585-994-0674-3.

Повний текст джерела

Анотація:

Abstract. Precambrian glaciations appear to be confined to two periods, one in the early Proterozoic between 2.5 and 2 Gyears BP (Before Present) and the other in the late Proterozoic between 1 and 0.57 Gyear BP. Possible reasons for these broad features of the Precambrian climate have been investigated using a simple model for the mean surface temperature of the Earth that partially compensates for the evolution of the Sun by variations in the atmospheric CO2 content caused by outgassing, the formation of continents and the weathering of the Earth's land surface. It is shown that the model can explain the main changes in the Precambrian climate if the early Proterozoic glaciations were caused by a major episode of continental land building commencing about 3 Gyears BP while the late Proterozoic glaciations resulted from biologicallyenhanced weathering of the land surface due to the proliferation of life forms in the transition from the Proterozoic to the Phanerozoic that began about 1 Gyear BP.

Стилі APA, Harvard, Vancouver, ISO та ін.

21

Donovan, Stephen K. "The fit of the continents in the late Precambrian." Nature 327, no. 6118 (May 1987): 139–41. http://dx.doi.org/10.1038/327139a0.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

22

Kennedy, M. "Late Precambrian Oxygenation; Inception of the Clay Mineral Factory." Science 311, no. 5766 (March 10, 2006): 1446–49. http://dx.doi.org/10.1126/science.1118929.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

23

Thompson, Margaret D. "Evidence for a late Precambrian caldera in Boston, Massachusetts." Geology 13, no. 9 (1985): 641. http://dx.doi.org/10.1130/0091-7613(1985)13<641:efalpc>2.0.co;2.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

24

Walker, J. Douglas, David W. Klepacki, and B. C. Burchfiel. "Late Precambrian tectonism in the Kingston Range, southern California." Geology 14, no. 1 (1986): 15. http://dx.doi.org/10.1130/0091-7613(1986)14<15:lptitk>2.0.co;2.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

25

Plumb, K. A. "Subdivision and correlation of late Precambrian sequences in Australia." Precambrian Research 29, no. 1-3 (June 1985): 303–29. http://dx.doi.org/10.1016/0301-9268(85)90072-5.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

26

Lewchuk, M. T., and D. T. A. Symons. "Paleomagnetism of the Late Precambrian Coldwell Complex, Ontario, Canada." Tectonophysics 184, no. 1 (November 1990): 73–86. http://dx.doi.org/10.1016/0040-1951(90)90121-n.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

27

Yu, Yongjae, and David J. Dunlop. "Paleointensity determination on the Late Precambrian Tudor Gabbro, Ontario." Journal of Geophysical Research: Solid Earth 106, B11 (November 10, 2001): 26331–43. http://dx.doi.org/10.1029/2001jb000213.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

28

COMPSTON, W., A. E. WRIGHT, and P. TOGHILL. "Dating the Late Precambrian volcanicity of England and Wales." Journal of the Geological Society 159, no. 3 (May 2002): 323–39. http://dx.doi.org/10.1144/0016-764901-010.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

29

Dallmeyer, R. D., and R. D. Nance. "40Ar/39Ar ages of detrital muscovite within early Paleozoic overstep sequences, Avalon composite terrane, southern New Brunswick: implications for extent of late Paleozoic tectonothermal overprint." Canadian Journal of Earth Sciences 27, no. 9 (September 1, 1990): 1209–14. http://dx.doi.org/10.1139/e90-128.

Повний текст джерела

Анотація:

Concentrates of coarse-grained detrital muscovite from the Ratcliffe Brook Formation (lowermost Cambrian) display internally discordant 40Ar/39Ar age spectra. Gas fractions evolved at intermediate and high experimental temperatures record apparent ages of ca. 610–620 Ma. These are interpreted as dating initial cooling through temperatures appropriate for intracrystalline retention of 40Ar and may indicate derivation from mylonite zones developed within proximal late Precambrian granitic rocks. Gas fractions evolved at lower experimental temperatures record patterns of spectra discordance that suggest the constituent grains experienced partial, intracrystalline diffusive loss of 40Ar during a late Paleozoic, low-grade thermal overprint. A muscovite concentrate from pelitic schist beneath the allochthonous, latest Precambrian Cranberry Head granite records a 40Ar/39Ar plateau age of 318 ± 1 Ma. This is interpreted as closely dating Late Carboniferous thrust emplacement of the allochthon.

Стилі APA, Harvard, Vancouver, ISO та ін.

30

Maslov, A. V., V. N. Podkovyrov, E. Z. Gareev, and O. V. Graunov. "Paleoclimate changes in the late precambrian: Evidence from the upper precambrian section of the South Urals." Lithology and Mineral Resources 51, no. 2 (March 2016): 117–35. http://dx.doi.org/10.1134/s002449021602005x.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

31

Jankauskas, Tadas, and William Sarjeant. "Boris V. Timofeyev (1916-1982): Pioneer of Precambrian and Early Paleozoic Palynology." Earth Sciences History 20, no. 2 (January 1, 2001): 178–92. http://dx.doi.org/10.17704/eshi.20.2.97jm433t7020456r.

Повний текст джерела

Анотація:

Boris Timofeyev is a name little known to scientists outside the former U.S.S.R. However, he was a principal pioneer in the study of Late Precambrian and Early Palaeozoic microfossils (in particular, acritarchs). Though by no means free from error, his contributions on the microbiota of the Precambrian to Devonian are of lasting importance. An account of his life and researches is presented, along with a comprehensive listing of his scientific publications.

Стилі APA, Harvard, Vancouver, ISO та ін.

32

Pystin, A. M., O. V. Grakova, Yu I. Pystina, E. V. Kushmanova, K. S. Popvasev, I. L. Potapov, and V. B. Khubanov. "U-Pb (LA-SF-ICP-MS) dating and probable provenance of detrital zircons from terrigenous deposits of the Upper Precambrian of the Subpolar Urals." LITHOSPHERE (Russia) 22, no. 6 (January 5, 2023): 741–60. http://dx.doi.org/10.24930/1681-9004-2022-22-6-741-760.

Повний текст джерела

Анотація:

Research subject. Upper Precambrian metaterrigenous deposits of the northern part of the Lyapinsky anticlinorium in the Subpolar Urals.Material and methods. From the metaterrigenous rocks of the Upper Precambrian section of different stratigraphic levels, monofractions of zircons were isolated and their optical and isotope-geochronological (U-Pb LA-SF-ICPMS) studies were performed.Results. Age boundaries of the formation of the Puivinskaya, Khobeinskaya, and Moroinskaya Formations in the Subpolar Urals were specified. A comparison was carried out of age populations of detrital zircons from metaterrigenous deposits of the Subpolar Urals and terrigenous sequences of adjacent regions similar in age. The age boundaries and the proposed location of crystalline complexes, the probable provenance areas of terrigenous material, were established.Conclusions. The lower age limit of the formation of the basal layers of the Upper Precambrian of the Subpolar Urals does not go beyond the Late Riphean. The north-eastern periphery of the East European Platform, including the Subpolar Urals, in the Late Precambrian belonged to the same continental margin, and the accumulation of the Middle-North Timan and Subpolar Ural Upper Riphean sediments occurred in the common sedimentation basin. The lower age boundary of the formation of the Puivinskaya Formation (about 1000 Ma) determines the probable formation time of the Timan passive margin.

Стилі APA, Harvard, Vancouver, ISO та ін.

33

Williams, Harold, R. T. Gillespie, and Otto Van Breemen. "A late Precambrian rift-related igneous suite in western Newfoundland." Canadian Journal of Earth Sciences 22, no. 11 (November 1, 1985): 1727–35. http://dx.doi.org/10.1139/e85-181.

Повний текст джерела

Анотація:

A granite that yields a U–Pb zircon age of 602 ± 10 Ma is associated with mafic and silicic volcanic rocks and metamorphic equivalents near Deer Lake in western Newfoundland. The granitic rocks are named the Round Pond granite, and the combined granite–volcanic suite is assigned to the Hughes Lake complex. All of the rocks are contained in the Hughes Lake structural slice that occurs above other allochthonous rocks and the autochthonous Cambrian–Ordovician carbonate sequence of western Newfoundland.The Round Pond granite is cut by metadiabase dykes. Mafic volcanic rocks, interpreted as coeval with the dykes, occur along the southeast side of the granite. A thick sequence of arkosic metagreywackes and psammitic to pelitic schists of the Mount Musgrave Group occurs stratigraphically above the mafic volcanic rocks. Regional correlations imply that the Mount Musgrave Group is of late Precambrian – Early Cambrian age, thus setting an upper stratigraphic limit to the age of the Hughes Lake complex.Perthitic and granophyric textures and the chemistry of the Round Pond granite are typical of anorogenic high-level hypersolvus intrusions. Nearby pink silicic volcanic rocks are probably consanguineous with the granite and together with the mafic volcanics form a bimodal suite.Bimodal volcanic suites and related mafic dykes and granitic intrusions imply rift tectonic settings. Occurrences along the west flank of the Appalachian Orogen are equated with the initiation of an ancient continental margin and the opening of an Iapetus Ocean. The 602 ± 10 Ma age of the Round Pond granite dates the rifting in western Newfoundland. Older isotopic ages on similar rocks in the southern Appalachians of the United States suggest a diachronous Precambrian rifting and Iapetus opening that propagated northward, much like the Mesozoic opening of the North Atlantic Ocean.

Стилі APA, Harvard, Vancouver, ISO та ін.

34

Dallmeyer, R. David, and R. Damian Nance. "Tectonic implications of 40Ar/39Ar mineral ages from late Precambrian – Cambrian plutons, Avalon composite terrane, southern New Brunswick, Canada." Canadian Journal of Earth Sciences 29, no. 11 (November 1, 1992): 2445–62. http://dx.doi.org/10.1139/e92-192.

Повний текст джерела

Анотація:

Within the Avalon composite terrane exposed in southern New Brunswick, late Precambrian, low-grade volcanic–sedimentary sequences are juxtaposed against late Precambrian gneisses (Brookville Gneiss) and older platformal metasedimentary rocks (Green Head Group) along the Caledonia Fault. Both assemblages host petrographically similar suites of calc-alkalic dioritic and granodioritic plutons. Those intruding volcanic–sedimentary sequences (Caledonia terrane) record ca. 615–625 Ma crystallization ages typical of arc-related magmatism throughout the Avalon composite terrane. However, 40Ar/39Ar age data from stocks intruding gneisses and platformal metasedimentary rocks (Brookville terrane) suggest significantly younger crystallization ages.36Ar/40Ar versus 39Ar/40Ar isotope correlation ages recorded by hornblende are interpreted to closely date postmagmatic cooling within six plutons: Fairville Granite (547 ± 1 Ma); French Village Quartz Diorite (539 ± 2 and 537 ± 1 Ma); Rockwood Park Granodiorite (529 ± 2 and 523 ± 3.5 Ma); Musquash Granite (526 ± 2 Ma); Milkish Head Granite (Red Bridge pluton, 520 ± 1.5 Ma); Lepreau Diorite (Talbot Road pluton, 519 ± 2 Ma and Hansen Stream pluton, 518 ± 1.5 Ma. A hornblende isotope correlation age of 530 ± 2 Ma from penetratively foliated amphibolite within the French Village Quartz Diorite suggests that the magmatic activity was locally accompanied by ductile shear. Muscovite within granitic pegmatite in the Brookville Gneiss records a 40Ar/39Ar plateau age of 510 ± 1 Ma interpreted to date final phases of associated magmatic activity.Arc-related magmatism extending into the Cambrian contrasts with the characteristic tectono-stratigraphic record in the Avalon composite terrane where late Precambrian igneous rocks are overstepped by Cambrian–Ordovician shallow-marine strata with only a local and minor record of rift-related volcanic activity. Although the Brookville terrane shows affinities with the Avalon composite terrane during the late Precambrian, the 40Ar/39Ar age data suggest that it was isolated as a distinct tectono-stratigraphic element by the Early Cambrian.

Стилі APA, Harvard, Vancouver, ISO та ін.

35

Gibson, Gail G. "Trace fossils from Late Precambrian Carolina slate belt, south-central North Carolina." Journal of Paleontology 63, no. 1 (January 1989): 1–10. http://dx.doi.org/10.1017/s0022336000040889.

Повний текст джерела

Анотація:

The volcanosedimentary sequence of the Carolina slate belt in south-central North Carolina was long thought to be unfossiliferous; however, the 5,484–7,315 meters of dominantly evenly bedded siltstones and mudstones have recently yielded body fossils of the late Precambrian Ediacarian fauna and a Middle Cambrian trilobite assemblage. Ongoing stratigraphic studies in the Carolina slate belt of southern North Carolina have now revealed trace fossils representing the ichnotaxa Gordia arcuata?, ?Helminthopsis sp., Monocraterion sp., Neonerites biserialis, N. uniserialis, ?Neonerites sp., Planolites beverlyensis, P. montanus, ?Planolites sp., Syringomorpha nilssoni?,? Tomaculum sp., Torrowangea sp., and three additional indeterminate ichnogenera. These trace fossils, lacking ornamentation and complex patterns, compare favorably with ichnofossil assemblages from Late Proterozoic stratigraphic sequences (Ichnofossil Zone I) elsewhere and support the late Precambrian age interpretation for the Carolina slate belt in south-central North Carolina.

Стилі APA, Harvard, Vancouver, ISO та ін.

36

Degtyarev, K. E., A. A. Tretyakov, E. B. Salnikova, and A. B. Kotov. "Kumystin granosyenites complex of the late Cryogenian in Bolshoi Karatau (South Kazakhstan), age substantiation." Доклады Академии наук 484, no. 5 (May 16, 2019): 579–83. http://dx.doi.org/10.31857/s0869-56524845579-583.

Повний текст джерела

Анотація:

The results of U–Pb geochronological studies of quartz syenites of the Kumystin complex of the Bolshoi Karatau ridge in southern Kazakhstan are presented and their late Neoproterozoic (717 ± 4 Ma) age is substantiated. Kumystin syenites complex together with rhyolites and basalts of the Kainar Formation are the youngest formations taking part in the basement of Karatau-Dzhebagly precambrian massif and formed in the second half of Cryogenian. The data set about the ages of the youngest complexes taking part in the basement of precambrian massifs of the Western part of the Central Asian belt indicates that the ending of magmatic activity within various massifs occurred asynchronously during the Neoproterozoic.

Стилі APA, Harvard, Vancouver, ISO та ін.

37

Williams, GE. "Solar Affinity of Sedimentary Cycles in the Late Precambrian Elatina Formation." Australian Journal of Physics 38, no. 6 (1985): 1027. http://dx.doi.org/10.1071/ph851027.

Повний текст джерела

Анотація:

Climatic cyclicity is recorded by regular variations in the thickness of siltstone-fine sandstone laminae interpreted as annual deposits (varves) within the Elatina Formation, a late Precambrian ( - 680 million years old) periglacial lake deposit in the Flinders Ranges, South Australia. Earlier conclusions, based on the study of limited rock outcrop, that the climatic cycles reflect solar variability are strongly supported by a complexity of periods revealed through study of drill cores of the - 10 m thick varved sequence. The wealth of new data generated by the drilling program, which was CSIRO-sponsored largely because of the support of R. G. Giovanelli, has application to solar physics and solar-planetary science.

Стилі APA, Harvard, Vancouver, ISO та ін.

38

Pystina, Yu I., A. M. Pystin, and V. B. Hubanov. "The Lower Precambrian in the structure of paleozoic in the Subpolar Urals." Доклады Академии наук 486, no. 5 (June 20, 2019): 572–76. http://dx.doi.org/10.31857/s0869-56524865572-576.

Повний текст джерела

Анотація:

In many polymetamorphic complexes of the Urals, rocks with Early Precambrian age marks have been established. But only with respect to the two polymetamorphic complexes located on the western slope of the Southern Urals: the Taratash and Aleksandrov, their indisputable belonging to the Archean-Paleoproterozoic section is recognized. They are framed by weakly metamorphosed Lower Riphean sediments and reliable geochronological data are obtained from them, which unambiguously indicate the Early Precambrian age of rock metamorphism. The available Early Precambrian age datings for other Ural polymetamorphic complexes (with the prevailing number of Late Precambrian and Paleozoic age values) are interpreted differently. Therefore, their attitude to the Lower Precambrian section has been disputed by many researchers. In the article, for the first time, based on the results of mass U-Pb dating of metamorphic zircons from the gneiss of the Nyrtin polymetamorphic complex of the Subpolar Urals, taking into account the available data, the Paleoproterozoic age of the earliest stage of rocks metamorphism (2127 ± 31 Ma) is substantiated. This gives grounds to assert that the complex under consideration, as well as the Taratash and Alexandrov complexes of the Southern Urals, belongs to the Lower Precambrian formations involved in the structure of Uralides.

Стилі APA, Harvard, Vancouver, ISO та ін.

39

El-Sayed, M. M., Alexandria M. A. Hassanen, and M. A. Obeid. "Geochemistry and petrogenesis of Late Precambrian tonalite - granodiorite - syenogranite series at Umm Shaddad district (Egypt)." Neues Jahrbuch für Mineralogie - Abhandlungen 175, no. 1 (July 1, 1999): 29–51. http://dx.doi.org/10.1127/njma/175/1999/29.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

40

Ghent, Edward D., and James R. O'Neil. "Late Precambrian marbles of unusual carbon-isotope composition, southeastern British Columbia." Canadian Journal of Earth Sciences 22, no. 3 (March 1, 1985): 324–29. http://dx.doi.org/10.1139/e85-032.

Повний текст джерела

Анотація:

Carbon- and oxygen-isotope analyses were made of both carbonates and graphites from several Precambrian metamorphic samples from British Columbia. The carbon-isotope data are unusual in that the δ13C values of many marbles are very high, up to 9.9, and the most positive values occur in the sillimanite-zone rocks. The δ13C values of graphite are also relatively high, and the 13C fractionations between calcite and graphite suggest that (1) the rocks attained and retained carbon-isotope equilibrium during metamorphism, and (2) the temperature of graphite equilibration in marbles from the sillimanite zone is 650–690 °C, in agreement with temperatures estimated from mineralogical phase equilibria.Possible precursor carbonates for the 13C-rich marbles in British Columbia include (1) Precambrian carbonate-secreting organisms such as algae that participate in reactions with large kinetic isotope effects, (2) carbonates that exchanged carbon isotopes with a large reservoir of organic material prior to metamorphism, and (3) travertines.

Стилі APA, Harvard, Vancouver, ISO та ін.

41

ABDEL-KARIM, Abdel-Aal M. "Petrogenesis of late Precambrian younger granites from southwest Sinai, Egypt." JOURNAL OF MINERALOGY, PETROLOGY AND ECONOMIC GEOLOGY 91, no. 5 (1996): 185–95. http://dx.doi.org/10.2465/ganko.91.185.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

42

Shukla, Manoj, V. C. Tewari, and V. K. Yadav. "Late Precambrian microfossils from Deoban Limestone Formation, Lesser Himalaya, India." Journal of Palaeosciences 35, no. (1-3) (December 31, 1986): 347–56. http://dx.doi.org/10.54991/jop.1986.1549.

Повний текст джерела

Анотація:

A well-preserved microbiota consisting of filamentous Cyanobacteria, viz., Oscillatoriopsis, Cyanonema, Siphonophycus, Eomycetopsis, Gunflintia and Animikiea; spheroidal unicells, viz., Glenobotrydion, Globophycus, Sphaerophycus and Myxococcoides; Eubacteria, viz., Archaeotrichion, Biocatenoides; and acritarch (?plankton) Kildinosphaera, is described from petrographic thin sections of cherts from the Deoban Formation, Garhwal Lesser Himalaya. The assemblage has been compared with other authentic Proterozoic records. The palaeomicrobial community is interpreted to have inhabited a protected shallow intertidal environment.

Стилі APA, Harvard, Vancouver, ISO та ін.

43

Stern, Robert J., Kent C. Nielsen, Eric Best, Mohamed Sultan, Raymond E. Arvidson, and Alfred Kröner. "Orientation of late Precambrian sutures in the Arabian-Nubian shield." Geology 18, no. 11 (1990): 1103. http://dx.doi.org/10.1130/0091-7613(1990)018<1103:oolpsi>2.3.co;2.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

44

Compston, W., I. S. Williams, R. J. F. Jenkins, V. A. Gostin, and P. W. Haines. "Zircon age evidence for the Late Precambrian Acraman ejecta blanket." Australian Journal of Earth Sciences 34, no. 4 (December 1987): 435–45. http://dx.doi.org/10.1080/08120098708729424.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

45

Crowley, Thomas J., and Steven K. Baum. "Effect of decreased solar luminosity on late Precambrian ice extent." Journal of Geophysical Research 98, no. D9 (1993): 16723. http://dx.doi.org/10.1029/93jd01415.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

46

Baum, Steven K., and Thomas J. Crowley. "GCM response to Late Precambrian (∼590 Ma) ice-covered continents." Geophysical Research Letters 28, no. 4 (February 15, 2001): 583–86. http://dx.doi.org/10.1029/2000gl011557.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

47

Dixon, T. H., and M. P. Golombek. "Late Precambrian crustal accretion rates in northeast Africa and Arabia." Geology 16, no. 11 (1988): 991. http://dx.doi.org/10.1130/0091-7613(1988)016<0991:lpcari>2.3.co;2.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

48

Jenkins, Richard J. F. "The enigmatic Ediacaran (late Precambrian) genus Rangea and related forms." Paleobiology 11, no. 3 (1985): 336–55. http://dx.doi.org/10.1017/s0094837300011635.

Повний текст джерела

Анотація:

The late Precambrian genus Rangea Gürich, 1929, a frond-like fossil composed of repeated foliate elements, is one of the first discovered forms belonging to the now widely known soft-bodied assemblages characterizing the Ediacaran Period. Rangea occurs together with the genera Pteridinium Gürich, 1933, and Ernietta Pflug, 1966, in the lower parts of the Nama Group, Namibia (South West Africa).Investigation of the preservation and structure of Rangea, utilizing a methodology similar to that established by Wade (1968, 1971), indicates that it was probably a colonial octocoral consisting of a large tapering primary polyp, or oozoid, and a number of leaf-shaped, conjoined fronds which bore the feeding polyps; it is suggested to belong to a group of early Ediacaran anthozoans which provide a fossil link between the still living Telestacea and Pennatulacea. Similar investigations of Pteridinium and Ernietta disclose that their structure is different from Rangea and does not support ideas that they are related to it.

Стилі APA, Harvard, Vancouver, ISO та ін.

49

Balé, Pascal, and Jean-Pierre Brun. "Late Precambrian thrust and wrench zones in northern Brittany (France)." Journal of Structural Geology 11, no. 4 (January 1989): 391–405. http://dx.doi.org/10.1016/0191-8141(89)90017-5.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

50

Martelat, Jean-Emmanuel, Jean-Marc Lardeaux, Christian Nicollet, and Raymond Rakotondrazafy. "Strain pattern and late Precambrian deformation history in southern Madagascar." Precambrian Research 102, no. 1-2 (July 2000): 1–20. http://dx.doi.org/10.1016/s0301-9268(99)00083-2.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Статті в журналах з теми "Late Precambrian"

Оформте джерело за APA, MLA, Chicago, Harvard та іншими стилями