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| Titel |
Evolution of a crack-seal calcite vein network in limestone : a high resolution structural, microstructural and geochemical study from the Jebel Akhdar high pressure cell, Oman Mountains |
| VerfasserIn |
Simon Virgo, Max Arndt, Paul Stenhouse, Stephen F. Cox, Christoph Hilgers, Janos L. Urai |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250048630
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| Zusammenfassung |
| We present a workflow to acquire and create a 1.2 Gipapixel high-resolution outcrop
panorama of a polished limestone pavement on the Western flank of Jabal Shams in the Oman
Mountains. The outcrop panorama serves as a basemap to integrate structural, microstructural
and geochemical investigations in a Geographic Information System. The outcrop provides
insight to the evolution of a high-density calcite vein network in Limestone. The vein network
as it appears in the outcrop evolved dynamically. Subvertical veins with variable strike
directions show mutually overprinting age relationships, indicating a horizontal extension
under near-lithostatic fluid pressure conditions. The high vein density and lack of
abutting of veins indicates a quick restoration of bulk strength by fracture healing.
Large vein apertures are formed by both vein stacking and a multitude of crack-seal
cycles, as indicated by hostrock inclusions. The episodic growth of veins, which is
accompanied by episodic fluid flow, is also suggested by large isotope variations
across single veins. Existing veins act as mechanical discontinuities depending
on orientation and their sealing driven strength regeneration. They significantly
influence the formation of new fractures and largely control the geometry of the
vein network. Stable isotope measurements imply alteration of the host rock by
external fluids prior to the formation of the vein network. The majority of the veins
show a rock-buffered isotopic signature. Low δ13C values in some veins suggest an
influx of oxidized light hydrocarbons. The fluid system was opened by E-W striking
normal faults, which is preserved in fault related veins by increased δ18O values. |
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