precambrian in English
By the early years of the twentieth century, as the geology of the continents began to be better known, it was realized that Permian and Precambrian glacial deposits occur virtually on all continents and at low latitudes.
Use "precambrian" in a sentence
1. Most Anorthosites formed during Precambrian times.
2. Beresite (2) metasomatism (2) mineral deposits, genesis (2) Paleozoic Ordovician Lower Ordovician (1) Precambrian upper Precambrian Proterozoic Neoproterozoic Riphean upper Riphean
3. Amygdaloidal basalt from the Precambrian of northern Michigan, USA
4. No records of Brachiopods are known from the Precambrian
5. 20 Hoffman possesses an encyclopedic knowledge of Precambrian continental geology.
6. Young Cratons have a folded base of Paleozoic and, partly, late Precambrian origin.
7. Algonkian A Precambrian system ( Van Eysinga, 1975) of equivalent time period to the Proterozoic
8. Precambrian rocks of the Canadian Shield form the eastern margin of the McTavish Arm.
9. Ancient Cratons were formed during the Precambrian, mostly by the start of the late Proterozoic
10. The Archean extended from the origin of the earth (see Precambrian) to about 2,500 million years ago
11. They intersect Precambrian country rocks composed of potassium feldspar-biotite-granitic-mobilisates and chloritised biotite mica schists.
12. Anthozoa: Fossil Record The origins of the Anthozoa lie in the Precambrian, but concrete evidence is sketchy
13. Southern Missouri rises to the Ozark Mountains, a dissected plateau surrounding the Precambrian igneous St. Francois Mountains.
14. Precambrian Cratons are commonly cored by Archaean granite-greenstone terrains and may be partly covered by sedimentary platform sequences.
15. The crushed-rock aggregates under study were obtained from Precambrian acid igneous rock outcrops in and around Gauhati.
16. Ediacaran Biota, Precambrian: South China - "spiral organism" interpreted as early stem-group Ctenophore by Tang et al
17. The roots of these volcanic mountains and the action of Precambrian seas formed the Iron Range of northern Minnesota.
18. Precambrian amphibolites and quartz-mica schists in the Saidapuram-Podalakuru area fall within the almandine-amphibolite facies of regional metamorphism.
19. 24 The early Precambrian in Jilin province includes the Archaeozoic granite-greenstone belt, early Proterozoic Ji'an Group and mid Proterozoic Laoling Group .
20. 21 Extensive areas within continental platforms are formed of basement, a complex of metamorphic and igneous rocks of Palaeozic or Precambrian age.
21. The ArcheanThe eon that constitutes the earlier (or middle) part of the Precambrian eon, or the system of rocks deposited during it
22. Amphibolites are hornblende-plagioclase rocks of metamorphic origin that are widely distributed, especially in Precambrian shield areas and in younger orogenic belts
23. The Boulder Creek Batholith is the best known of several large Precambrian Batholiths of similar rock composition that crop out across central Colorado
24. Archean [ är-kē ′ən ] The earlier of the two divisions of the Precambrian Eon, from about 3.8 to 2.5 billion years ago
25. In the latest PreCambrian and Cambrian, the supercontinent Rodinia, which was centered about the South Pole, broke apart, and crustal blocks drifted northward.
26. During latest Precambrian time, in northwest Mexico, an about 2,000 m thick sequence of conglomerate, sandy shale and dolomite, containingCollenia, Cryptozoa and other organisms, accumulated on top of the eroded older Precambrian metamorphics and granitic rocks, that formed the northeast flank of the miogeosynclinal part of the ancestral North American Cordilleran Geosyncline, representing a near-shore facies.
27. The lower (younger?) thrust emplaces Precambrian basalts and tuffaceous siltstones (Coldbrook Group) over alluvial sediments of the Boss Point and Tynemouth Creek formations (Westphalian A–B).
28. The Precambrian could be divided into five "natural" eons, characterized as follows: Accretion and differentiation: a period of planetary formation until giant Moon-forming impact event.
29. What does Archean mean? Of, relating to, or being the older of the two divisions of Precambrian time, from about 3.8 to 2.5 billion years ago, m
30. Fossil Andosols are known from areas far from present-day volcanic activity and have in some cases been dated as far back as the Precambrian 1.5 billion years ago.
31. The great span of Precambrian time is divided for convenience into two major parts—the Archean Eon (4,550-2,500 million years [or Ma]) and the Proterozoic Eon (2,500-570 Ma)
32. The major geological units are Precambrian metasediments partly mixed with younger (Cambrian) granites and associated pegmatites; cassiterite, columbite, tantalite, and gold are mined from alluvial deposits on a small scale.
33. Beltian Geosyncline, a linear trough in the Earth’s crust in which rocks of Precambrian age (about 4 billion to 542 million years ago) were deposited in the Northern Rocky Mountain region
34. Deep sea Anglerfish look like some kind of tragic holdover from the Precambrian Era, with their large head, dead eyes, fang-like teeth, and glowing “fishing rod” that extends from their dorsal
35. In the lazurite deposit of Malaya Bystraya, the country rocks are Precambrian stinking (fetid) dolomites which contain ancient hydrogen sulfide with δ34S from +19.0 to +33.4‰, and sulfate with δ34S=+44.9‰.
36. Cnidaria, phylum of multicellular, radially symmetrical invertebrates (eg, hydroids, jellyfish, sea anemones, corals) dating to late Precambrian era (630-570 million years ago).Formerly, phylum Coelenterata included Cnidarians and ctenophores (comb jellies)
37. 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.
38. Archean Eon, also spelled Archaean Eon, the earlier of the two formal divisions of Precambrian time (about 4.6 billion to 541 million years ago) and the period when life first formed on Earth.
39. 28 A craton includes a crystalline basement of commonly Precambrian rock called a shield, and a platform in which flat-lying or nearly flat-lying sediments or sedimentary rock surround the shield.
40. 11 The lower Proterozoic Badu Group is one of the oldest metamorphic rock series in the continental margin of Southeast China, and is an integral part of the early Precambrian Zhejiang-Fujian craton.
41. The sedimentary accumulation can be interpreted in terms of a sloping interface located under the network between sediments and Precambrian rock or a thick horizontal sedimentary layer underlying the south shore of the St. Lawrence River.
42. ‘The oldest Anthozoans are probably some of the polyp-like and sea pen-like fossils from the Vendian (late Precambrian).’ ‘In addition to their relevance as model organisms for understanding metazoan evolution, Anthozoans are ecologically important.’
43. There is a regional decrease in initial Sr87/Sr86 ratios, southwestward across the Yukon Crystalline Terrane. This may mean that Precambrian rocks extend under the Yukon Crystalline Terrane, but are absent under the adjoining Coast Plutonic Complex.
44. ‘The prominent basement rocks of the Brumado area are Precambrian in age and consist dominantly of gneisses, schists, and Amphibolite.’ ‘A uniform, regionally concordant layer of Amphibolite with occasional ultramafic pods, termed the Sta Amphibolite, overlies the Sta Series.’
45. The Mount Nansen ore deposit consists of a system of narrow steeply dipping veins in metamorphic rocks of Precambrian to Paleozoic age, andesitic volcanics and granodioritic to granitic intrusives of Mesozoic age, and Cretaceous to early Tertiary dacitic porphyries.
46. The geology of the buried Precambrian basement under Manitoulin Island in northern Lake Huron, Ontario, has been re-evaluated on the basis of aeromagnetic data, well cuttings, core samples, and rubidium–strontium and uranium–lead geochronologic data on some of the subsurface samples.
47. Archean: Of, relating to, or being the older of the two divisions of Precambrian time, from about 3.8 to 2.5 billion years ago, marked by an atmosphere with little free oxygen, the formation of the first rocks and oceans, and the development of unicellular life.
48. Moreover, according toMiyashiro regional metamorphism of his kyanite-sillimanite type (= Dalradian or Barrovian type) was common in Palaeozoic time, whereas that of his andalusite-sillimanite type and low-pressure intermediate group (Buchan type) took place in orogenic belts of Precambrian as well as Palaeozoic and Mesozoic age.
49. A number of the Vendian, or latest Precambrian, soft-bodied "medusoids" are now thought to represent benthic polyp-like organisms.Some of the frondlike fossils of the time could represent colonial Anthozoans similar to living "sea pens," Eoporpita is one such Vendian fossil that could
50. Two other Calderas are also postulated.-after Authors AB - Precambrian igneous rocks in the St Francois Mountains of SE Missouri consist of silicic volcanic rocks, mostly ash flow tuff, which crop out mostly in the W and SW part of the region, and epizonal granitic plutons which are mostly exposed in …