Reply to the discussion by J.W.F. Waldron and C.E. White on “Geochemical signature of Ordovician Mn-rich sedimentary rocks on the Avalonian shelf”1Appears in Canadian Journal of Earth Sciences, 2012, 49(6): 772–774 [doi: 10.1139/e2012-004].

2012 ◽  
Vol 49 (6) ◽  
pp. 775-780 ◽  
Author(s):  
Rolf L. Romer ◽  
Uwe Kroner
Keyword(s):  
Earth Sciences ◽  
Nova Scotia ◽  
Canadian Journal ◽  
Deep Water ◽  
Sedimentary Rocks ◽  
Geochronological Data ◽  
Early Ordovician ◽  
Geochemical Signature

In their comment, Waldron and White state that manganese-rich sedimentary rocks of Nova Scotia and Wales are Cambrian and were deposited in a deep-water turbidite basin called “Megumia” rather than on the Avalonian shelf. Available geochronological data are not in conflict with an Early Ordovician deposition age for manganese-rich sedimentary rocks north of the Rheic suture, including those of Nova Scotia and northern Wales. “Megumia” is part of the Avalonian plate, and the manganese-rich sediments were deposited on its shelf.

Discussion of “Geochemical signature of Ordovician Mn-rich sedimentary rocks on the Avalonian shelf”1Appears in Canadian Journal of Earth Sciences, 2011, 48(4): 703–718 [doi: 10.1139/e10-092].

2012 ◽  
Vol 49 (6) ◽  
pp. 772-774 ◽  
Author(s):  
John W.F. Waldron ◽  
Chris E. White
Keyword(s):  
Nova Scotia ◽  
Canadian Journal ◽  
Water Depth ◽  
Deep Water ◽  
Sedimentary Environment ◽  
Sedimentary Rocks ◽  
Geochemical Data ◽  
Geochemical Signature ◽  
North Wales ◽  
Mn Concentration

The paper “Geochemical signature of Ordovician Mn-rich sedimentary rocks on the Avalonian shelf” (Romer et al., published in 2011) describes six samples of which four are from the Meguma Supergroup of Nova Scotia. Previous work indicates that these samples are Cambrian and that they were deposited in a deep-water turbidite basin (“Megumia”), not on the Avalonian shelf. The geochemical data support models for Mn concentration, involving oxidation and reduction in a sedimentary environment but do not constrain water depth. Likely correlatives are in the Cambrian of North Wales and not in the European localities sampled by the authors.

Reply to the discussion of the reply by R.L. Romer and U. Kroner on “Geochemical signature of Ordovician Mn-rich sedimentary rocks on the Avalonian shelf” 1Appears in the Canadian Journal of Earth Sciences, 49(11): 1372–1377 [doi:10.1139/e2012-049].

2012 ◽  
Vol 49 (11) ◽  
pp. 1378-1383
Author(s):  
Rolf L. Romer ◽  
Uwe Kroner
Keyword(s):  
Earth Sciences ◽  
Canadian Journal ◽  
Sedimentary Rocks ◽  
Sedimentary Sequence ◽  
The Core ◽  
Geochemical Signature

Romer and Kroner (2012) stated “the core of the Harlech Dome (i) in part is made up of Ordovician deposits and (ii) contains tectonic repetitions”. In their comment, Schofield et al. (this issue) distort this statement and state that (i) we claim the entire sedimentary sequence of the Harlech Dome is Ordovician and (ii) we misinterpreted their zircon data. We disagree. In our reply, we demonstrate that the argumentation of Schofield et al. (this issue) is driven by circular argumentation and that their use and interpretation of U–Pb zircon data is inadequate.

scholarly journals The provenance of Jurassic and Lower Cretaceous clastic sediments offshore southwestern Nova Scotia

2017 ◽  
Vol 54 (1) ◽  
pp. 33-51 ◽  
Author(s):  
Dan-Cezar Dutuc ◽  
Georgia Pe-Piper ◽  
David J.W. Piper
Keyword(s):  
Nova Scotia ◽  
Deep Water ◽  
Lower Cretaceous ◽  
Middle Jurassic ◽  
Sedimentary Rocks ◽  
Petroleum Exploration ◽  
Ultramafic Rocks ◽  
Meguma Terrane ◽  
Clastic Sedimentary ◽  
Fundy Basin

Jurassic and Cretaceous sandstones in the Shelburne subbasin and Fundy Basin offshore Nova Scotia, are poorly known but are of current interest for petroleum exploration. The goal of this study is to determine the provenance of sandstones and shales, which will contribute to a better understanding of regional tectonics and paleogeography in the study area. Mineral and lithic clast chemistry was determined from samples from conventional cores and cuttings from exploration wells, using scanning electron microscopy and an electron microprobe. Whole-rock geochemical composition of shales was used to test the hypotheses regarding provenance of Mesozoic clastic sedimentary rocks in the SW Scotian Basin. Lower Jurassic clastic sedimentary rocks in the Fundy Basin contain magnetite, biotite, and chlorite, suggesting local supply from the North Mountain Basalt and Meguma Terrane, whereas pyrope and anthophyllite suggest small supply from distant sources. In the SW Scotian Basin, detrital minerals, lithic clasts, and shale geochemistry from Middle Jurassic to Early Cretaceous indicate a predominant Meguma Terrane source and transport by local rivers. Rare spinel and garnet grains of meta-ultramafic rocks, only in the Middle Jurassic at the Mohawk B-93 well, suggest minor supply from the rising Labrador rift, via the same river that transported distant sediments to the Fundy Basin. Lower Cretaceous sandstones from the Mohican I-100 well contain minor garnet, spinel, and tourmaline from meta-ultramafic rocks, characteristic of sediment supplied to the central Scotian Basin at that time. The dominant Meguma Terrane provenance precludes thick deep-water sandstones in the eastern part of the Shelburne subbasin, but the evidence of Middle Jurassic distant river supply through the Fundy Basin is encouraging for deep-water reservoir quality in the western part.

A Middle Cambrian trilobite faunule from the Meguma Group of Nova Scotia

1991 ◽  
Vol 28 (11) ◽  
pp. 1843-1853 ◽  
Author(s):  
Brian R. Pratt ◽  
John W. F. Waldron
Keyword(s):  
Nova Scotia ◽  
Middle East ◽  
West Africa ◽  
Deep Water ◽  
Middle Cambrian ◽  
Early Ordovician ◽  
Cambrian Trilobite ◽  
East And West ◽  
Faunal Similarity

The Meguma Group of southern Nova Scotia is a thick succession of mostly deep-water siliciclastic sedimentray rocks of uncertain age. Previous fossil finds have been in the Halifax Formation of the upper part of the sequence and have provided Early Ordovician ages. A newly discovered trilobite-bearing bed from the underlying Goldenville Formation yields Middle Cambrian taxa of Acado-Baltic affinity. Specimens belonging to Paradoxides (s.l.), Agraulos, Dorypyge, and Ellipsocephalidae indicate that the Meguma Group is an exotic succession with faunal similarity to the adjacent Avalon Terrane and to Middle Cambrian successions in Europe, the Middle East, and west Africa.

The sequence and correlation of Early Ordovician (Arenig) graptolite faunas in the Richardson Trough and Misty Creek Embayment, Yukon Territory and District of Mackenzie, Canada

2006 ◽  
Vol 43 (12) ◽  
pp. 1791-1820 ◽  
Author(s):  
D E Jackson ◽  
A C Lenz
Keyword(s):  
Northwest Territories ◽  
Deep Water ◽  
Yukon Territory ◽  
Early Ordovician ◽  
The Road ◽  
Bedded Chert ◽  
First Occurrence ◽  
Mackenzie Mountains ◽  
First Time

Four graptolite biozones are recorded from the Arenig portion of the Road River Group in the Richardson and Mackenzie mountains in the Yukon and Northwest Territories. In ascending order, these zones are Tetragraptus approximatus, Pendeograptus fruticosus, Didymograptus bifidus, and Parisograptus caduceus australis (new). The Castlemainian stage may be represented by nongraptolitic massive bedded chert. The Arenig–Llanvirn boundary is drawn below the first occurrence of Undulograptus austrodentatus. Fifty-four graptolite taxa are present, and 16 of these species and subspecies are recorded for the first time in this deep-water biotope, namely, Didymograptus? cf. adamantinus, D. asperus, D. dilatans, D. cf. kurcki, D. validus communis, Holmograptus aff. leptograptoides, H. sp. A, Isograptus? sp. nov. A, I. ? dilemma, Keblograptus geminus, Pseudisograptus manubriatus harrisi, Ps. m. koi, Ps. m. janus, Ps. cf. tau, Xiphograptus lofuensis, and Zygograptus cf. abnormis.

scholarly journals Canadian Journal of Earth Sciences

Nature ◽  
1964 ◽  
Vol 203 (4951) ◽  
pp. 1227-1227 ◽  
Keyword(s):  
Earth Sciences ◽  
Canadian Journal
Sign in / Sign up

Export Citation Format

Share Document