scispace - formally typeset
Search or ask a question
Topic

Ankerite

About: Ankerite is a research topic. Over the lifetime, 859 publications have been published within this topic receiving 23960 citations.


Papers
More filters
Journal ArticleDOI
TL;DR: In the Callovian-oxfordian (COx) clayy unit of the Paris Basin at depths between 400 and 500 m depth, the authors in this article combined new mineralogical and isotopic data to describe the sedimentary history of the COx unit.

62 citations

Journal ArticleDOI
TL;DR: The Rose Hill Formation consists of open-marine to brackish-water olive clay shale, but intercalated with this are thin layers of gray siltstone and red hematitic sandstone, ranging from orthoquartzite to subgraywacke in composition as mentioned in this paper.
Abstract: The Tuscarora Formation is a medium sandstone with a few layers of vein quartz pebbles. The lower, red portion is a subgraywacke to graywacke, and was deposited in a submerged deltaic-estuarine environment. The upper, white portion is a supermature orthoquartzite formed as a beach sand deposited during a period of declining relief. The source area lay to the southeast; during early Tuscarora deposition it consisted largely of older sediments and low-rank metamorphic rocks, but as erosion proceeded, the sedimentary cover was stripped off and the plutonic igneous sources became of increasing importance. The Rose Hill Formation consists largely of open-marine to brackish-water olive clay shale, but intercalated with this are thin layers of gray siltstone and red hematitic sandstone, rang ng from orthoquartzite to subgraywacke in composition. The hematitic sandstones were deposited in a more shallow marine oxidizing environment than the gray siltstones which are cemented with ankerite and quartz. Iron minerals are common in the Rose Hill, and hematite, chlorite pellets, ankerite, and pyrite show consistent environmental associations. The source area for the Rose Hill consisted of low-rank metamorphic plus plutonic igneous rocks. The Keefer Sandstone shows evidence of lagoon-border and beach-dune deposition and consists of immature to supermature orthoquartzite to subgraywacke sandstones. The source area had now become deeply eroded so that plutonic igneous rocks dominated, but there were still some low-rank metamorphic rocks exposed. High rounding was accomplished in one cycle of deposition in the beach and dune environments of the upper Tuscarora and upper Keefer sandstones; rounding potency varied markedly from bed to bed. Metamorphic rock fragments, because of their low resistance to abrasion, are found to be very useful as environmental indicators.

62 citations

Journal ArticleDOI
TL;DR: The mineralogy, elemental composition, and modes of occurrence of 49 elements in nine composite samples of Bobov Dol high-ash coals were studied by optical microscopy, scanning and transmission electron microscopy and chemical analysis as discussed by the authors.

60 citations

Journal ArticleDOI
TL;DR: Zebra dolomites, characterized by a repetition of dark grey (a) and light (b) coloured dolmite sheets building up abbabba-sequences, occur in Dinantian strata from deep boreholes (>2000m) south of the Brabant-Wales Massif in Belgium.
Abstract: Zebra dolomites, characterized by a repetition of dark grey (a) and light (b) coloured dolomite sheets building up abbabba-sequences, occur in Dinantian strata from deep boreholes (> 2000 m) south of the Brabant-Wales Massif in Belgium. These zebra dolomite sequences are several tens of metres thick. The dark grey dolomite sheets (a) consist of non-planar crystals, 80–150 μm in diameter. These crystals display a mottled red–orange luminescence and are interpreted to be replacive in origin. The white dolomite sheets (b) consist of coarse crystalline nonplanar b1 dolomite, which evolves outwards into transparent saddle shaped b2 dolomite. The b1 dolomites possess a mottled red–orange luminescence similar to the a dolomites, while the saddle shaped b2 rims display red to dark brown luminescent-zones. The b1 dolomites are possibly partly replacive and partly cavity filling. Their b2 rims display criteria typical for a cement origin. Locally, cavities exist between two succeeding white dolomite sheets. These cavities make up ≈5% of the zebra rocks and are locally filled by saddle shaped ankerite and/or xenomorphic ferroan calcite. Geochemical and fluid inclusion data (Th ≈ 120 °C) indicate a burial diagenetic origin for these zebra dolomites. The a and b1 dolomites are characterized by similar geochemical compositions and fluid inclusion data pointing toward a related origin. To explain the development of the zebra textures, suprahydrostatic pressures in conjunction with late Variscan tectonic compression are invoked. A model involving dolomitizing fluids expelled during the Variscan orogeny is proposed. An overpressured system is also invoked to explain the important porosity development, the creation of centimetre-scale subvertical displacements of the zebra pattern and the microfractures affecting the b1–b2 dolomite crystals.

60 citations

Journal ArticleDOI
01 Dec 1980-Fuel
TL;DR: In this paper, the effects of various sweep gases (N2, CO2, and H2O) on the decomposition and reaction of calcite and dolomite (ankerite) in Colorado oil shale is reported.

60 citations


Network Information
Related Topics (5)
Zircon
23.7K papers, 786.6K citations
84% related
Sedimentary rock
30.3K papers, 746.5K citations
84% related
Carbonate
34.8K papers, 802.6K citations
80% related
Basalt
18.6K papers, 805.1K citations
79% related
Continental crust
11.1K papers, 677.5K citations
78% related
Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202332
202270
202140
202027
201946
201842