The dolomite problem: evidence from 3D modeling, XRD and geochemical data  of Zechstein reefs (Upper Permian, Germany)

Geological 3D modeling delivers essential information on the distribution of enrichment zones and structures in (complex) mineral deposits and fosters a better guidance to subsequent exploration stages. The Paleoproterozoic Epembe carbonatite complex showcases the close relation between enrichment of specific elements (Nb, Ta, P, Total Rare Earth Element (TREE) + Y) and shear zones by structural modeling combined with geochemical interpolation. Three-dimensional fault surfaces based on structural field observations, geological maps, cross-sections, and drillhole data are visualized. The model shows a complex, dextral transpressive fault system. Three-dimensional interpolation of geochemical data demonstrates enrichment of Nb, Ta, P, and TREE + Y in small, isolated, lens-shaped, high-grade zones in close spatial distance to faults. Based on various indicators (e.g., oscillating variograms, monazite rims around the apatite) and field evidence, we see evidence for enrichment during hydrothermal (re-)mobilization rather than due to magmatic differentiation related to the formation of the alkaline system. This is further supported by geostatistical analysis of the three-dimensional distribution of Nb, Ta, P, and Light Rare Earth Elements (LREE) with respect to discrete shear zones.

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NEW INSIGHTS INTO THE ACTIVE PETROLEUM SYSTEMS IN THE COOPER AND EROMANGA BASINS, AUSTRALIA

The APPEA Journal ◽

10.1071/aj98016 ◽

1999 ◽

Vol 39 (1) ◽

pp. 263 ◽

Cited By ~ 5

Author(s):

C.J. Boreham ◽

R.E. Summons

Keyword(s):

Carbon Number ◽

Carbon Isotopic Composition ◽

Petroleum System ◽

Source Rocks ◽

Upper Permian ◽

Geochemical Data ◽

Indirect Measure ◽

Petroleum Systems ◽

Eromanga Basin ◽

Cooper Basin

This paper presents geochemical data—gas chromatography, saturated and aromatic biomarkers, carbon isotopes of bulk fractions and individual n-alkanes—for oils and potential source rocks in the Cooper and Eromanga basins, which show clear evidence for different source-reservoir couplets. The main couplets involve Cooper Basin source and reservoir and Cooper Basin source and Eromanga Basin reservoir. A subordinate couplet involving Eromanga Basin source and Eromanga Basin reservoir is also identified, together with minor inputs from pre-Permian source rocks to reservoirs of the Cooper and Eromanga basins.The source–reservoir relationships are well expressed in the carbon isotopic composition of individual n-alkanes. These data reflect primary controls of source and maturity and are relatively insensitive to secondary alteration through migration fractionation and water washing, processes that have affected the molecular geochemistry of the majority of oils. Accordingly, the principal Gondwanan Petroleum Supersystem originating from a Permian source of the Cooper Basin has been further subdivided into two petroleum systems associated with Lower Permian Patchawarra Formation and Upper Permian Toolachee Formation sources respectively. Both sources are characterised by n-alkane isotope profiles that become progressively lighter with increasing carbon number—negative n-alkane isotope gradient. The Patchawarra source is isotopically lighter than the Toolachee source. Reservoir placement of oil in either the Toolachee or Patchawarra formations is, in general, a good guide to its source and perhaps an indirect measure of seal effectiveness. The subordinate Murta Petroleum Supersystem of the Eromanga Basin is subdivided into the Birkhead Petroleum System and Murta Petroleum System to reflect individual contributions from Birkhead Formation and Murta Formation sources respectively. Both systems are characterised by n-alkane carbon isotope profiles with low to no gradient. The minor Larapintine Petroleum Supersystem has been tentatively identified as involving pre-Permian source rocks in the far eastern YVarburton Basin and western margin of the Warrabin Trough in Queensland.Eromanga source inputs to oil accumulations in the Eromanga Basin can be readily recognised from saturated and aromatic biomarker assemblages. However, biomarkers appear to over-emphasise local Eromanga sources. Hence, we have preferred the semi-quantitative assessment of relative Cooper and Eromanga inputs that can be made using n-alkane isotope data and this appears to be robust provided that Eromanga source input is greater than 25% in oils of mixed origin. Enhanced contributions from Birkhead sources are concentrated in areas of thick and mature Birkhead source rocks in the northeastern Patchawarra Trough. Pre-Permian inputs are readily recognised by n-alkanes more depleted in I3C compared with late Palaeozoic and Mesozoic sources.Long range migration (>50 km) from Permian sources has been established for oil accumulations in the Eromanga Basin. This, together with contributions from local Eromanga sources, highlights petroleum pro- spectivity beyond the Permian edge of the Cooper Basin. Deeper, pre-Permian sources must also be considered in any petroleum system evaluation of the Cooper and Eromanga basins.

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Stratabound copper-lead-zinc mineralisation in the Permo-Triassic of central East Greenland

Bulletin Grønlands Geologiske Undersøgelse ◽

10.34194/bullggu.v143.6685 ◽

1982 ◽

Vol 143 ◽

pp. 1-42

Author(s):

B Thomassen ◽

L.B Clemmensen ◽

H.K Schønwandt

Keyword(s):

Middle Triassic ◽

Lower Triassic ◽

Upper Triassic ◽

Alluvial Fan ◽

Upper Permian ◽

Geochemical Data ◽

East Greenland ◽

Lead Zinc ◽

Copper Lead ◽

Carbonate Buildup

Stratabound and stratiform copper-lead-zinc-mineralised horizons confined to specific sedimentary fades in the Permo-Triassic Jameson Land Basin of East Greenland were revealed during recent exploration and sedimentological studies. The occurrences are divided into fault-bounded-stratabound and stratabound-stratiform mineralisation. The first group comprises lead-zinc-copper mineralisation in Upper Permian limestone; the remaining mineralisation falls in the second group which is subdivided into mineralisation hosted in mudstones, in sandstones with mudflasers and in sandstones and conglomerates. A lithogeochemical programme helped to define the mineralised horizons in the Triassic. During the interpretation of the geochemical data an empiric statistical function was introduced which is an estimate of how anomalous the 95 per cent fractile is for individual elements compared with the frequency distribution around the median. The Upper Permian sediments host copper in basal shoreline conglomerates, zinc-lead-copper in lagoonal mudstones and lead-zinc-copper in carbonate buildup and shelf fades. The Lower Triassic contains copper-lead mineralisation in alluvial fan sediments, the Middle Triassic hosts lead-zinc-copper in sandy shoreline limestones and lagoonal mudstones and copper-lead-zinc in gypsiferous lacustrine sandstones and mudstones while the Upper Triassic contains copper in both dolomitic lacustrine sandstones and mudstones and in overlying carbonate-rich fluvial channel sandstones.

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Decision letter for "Geochronological and geochemical data of paragneiss and amphibolite from the Chencai Group in South China: Implications for petrogenesis and tectonic significance"

10.1002/gj.3845/v1/decision1 ◽

2020 ◽

Keyword(s):

South China ◽

Geochemical Data ◽

Tectonic Significance

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A Model Is Worth 1,000 Pictures: Applications of 3D-Modeling in Skull Base Surgery Neuroanatomy Education

10.1055/s-0040-1702387 ◽

2020 ◽

Author(s):

Christopher S. Graffeo ◽

Avital Perry ◽

Lucas P. Carlstrom ◽

Michael J. Link ◽

Jonathan Morris

Keyword(s):

Skull Base ◽

3D Modeling ◽

Skull Base Surgery

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3D modeling of the vascular system

Journal of Theoretical and Applied Vascular Research ◽

10.24019/jtavr.8 ◽

2016 ◽

Vol 1 (1) ◽

pp. 51-58 ◽

Cited By ~ 1

Author(s):

Jean François Uhl ◽

Maxime Chahim ◽

François Cros ◽

Amina Ouchene ◽

◽

...

Keyword(s):

Augmented Reality ◽

3D Modeling ◽

Vascular System ◽

Arterial System ◽

Chronic Venous Disease ◽

Venous Disease ◽

Software Products ◽

Operative Planning ◽

Morphological Modeling ◽

Pre Treatment

The 3D modeling of the vascular system could be achieved in different ways: In the venous location, the morphological modeling by MSCT venography is used to image the venous system: this morphological modeling tool accurately investigates the 3D morphology of the venous network of our patients with chronic venous disease. It is also a fine educational tool for students who learn venous anatomy, the most complex of the human body. Another kind of modeling (mathematical modeling) is used to simulate the venous functions, and virtually tests the efficacy of any proposed treatments. To image the arterial system, the aim of 3D modeling is to precisely assess and quantify the arterial morphology. The use of augmented reality before an endovascular procedure allows pre-treatment simulation, assisting in pre-operative planning as well as surgical training. In the special field of liver surgery, several 3D modeling software products are available for computer simulations and training purposes and augmented reality.

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