Citation:

epic.29640.d001

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Abstract:

As a result of a petrographical, mineralogical and geochemical characterization of the Ameghino Formation mudstones (Upper Jurassic- Lower Cretaceous, Antarctic Peninsula), "epiclastic" radiolaria-rich and mixed (radiolaria-rich + tuff) mudstone types were recognized. Contents of clastic material in the mudstones generally increase with younger paleontological age, but local exceptions to this trend have been found. The anoxic environment of the lower part of the sequence changes to more oxidizing conditions towards the top, in transition to the Hauterivian - Barrêmian conglomerates. Element to element correlations show good agreement with the normal differentiation trends of volcanic (andesite-rhyolite) rocks, suggesting that the overall sequence is mainly volcanic in origin with various grade of reworking. For example, the radiolaria-rich mudstone matrix could have been originated from very fine touffaceous suspensions deposited very slowly after the main fall of the tuffs. However, in the upper part of the sequence, some epiclastic supply is revealed by petrographic evidence and illite crystallinity index. The clay mineral association (illite, chlorite and illite-smectite mixed layers) is mainly of diagenetic origin in the stratigraphically lower sections. Low percentages of expandable layers in the illite-smectite mixed layers, as well as the general mineralogical association, suggest a late mesodiagenetic stage, and together with geological evidence, a relatively deep burial (> 1000 m - probably > 2500 m) and temperatures exceeding 100°C.

Coverage:

Latitude: -64.500000 * Longitude: -59.000000

Event(s):

Ameghino * Latitude: -64.500000 * Longitude: -59.000000 * Location: Ameghino Formation, Antarctic Peninsula * Method/Device: Geological sample (GEOS)

Parameter(s):

#	Name	Short Name	Unit	Principal Investigator	Comment
1	Sample code/label	Sample label		Scasso, R A
2	Sample ID	Sample ID		Scasso, R A
3	Quartz	Qz		Scasso, R A
4	Plagioclase	Pl		Scasso, R A
5	Feldspar	Fsp		Scasso, R A
6	Pyrite	Py		Scasso, R A
7	Calcite	Cal		Scasso, R A
8	Smectite	Sme		Scasso, R A
9	Illite	Ill		Scasso, R A
10	Chlorite	Chl		Scasso, R A
11	Minerals	Minerals		Scasso, R A	other
12	Lithology/composition/facies	Lithology		Scasso, R A
13	Silicon dioxide	SiO2	%	Scasso, R A
14	Aluminium oxide	Al2O3	%	Scasso, R A
15	Iron oxide, Fe2O3	Fe2O3	%	Scasso, R A
16	Manganese oxide	MnO	%	Scasso, R A
17	Magnesium oxide	MgO	%	Scasso, R A
18	Calcium oxide	CaO	%	Scasso, R A
19	Sodium oxide	Na2O	%	Scasso, R A
20	Potassium oxide	K2O	%	Scasso, R A
21	Titanium dioxide	TiO2	%	Scasso, R A
22	Phosphorus pentoxide	P2O5	%	Scasso, R A
23	Sulfur, total	TS	mg/kg	Scasso, R A
24	Rubidium	Rb	mg/kg	Scasso, R A
25	Strontium	Sr	mg/kg	Scasso, R A
26	Zinc	Zn	mg/kg	Scasso, R A
27	Zirconium	Zr	mg/kg	Scasso, R A

License:

Creative Commons Attribution 3.0 Unported (CC-BY-3.0)

Size:

1870 data points

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