High-pressure polymorphs recovered in terrestrial craters are evidence of meteoroid impact events on the Earth’s surface. Despite countless impact craters on the Moon, high-pressure polymorphs have not been reported to date in returned Apollo samples. On the other hand, recent studies report that the high-pressure polymorphs of silica, coesite and stishovite occur in shocked lunar meteorites. W...

Quarrying for aggregate material at Hornsby in New South Wales (Australia) exposed a >100 m-deep cross-section of the volcanic neck Jurassic diatreme, which extruded through Sydney Basin deposits. The reveals features many scales. Globally, there are very few instances such excellent 3D exposure. It is arguable that this exposure alone makes it geosite international value. However, evaluatio...

The Lonar impact crater in the Deccan Traps of the Indian peninsula provides unique opportunities to study physical and chemical processes of impact cratering on basaltic targets, because terrestrial impact craters on basalts are extremely rare. Such studies are needed for determining provenance and other parameters of the excavated rocks and the cratering phenomenon that may have implications ...

Kimberlite is described as a diverse and complex hybrid rock in the literature. It is also described as volatile rich, potassic, ultrabasic, igneous rocks that occur as volcanic pipes, dykes and sills1. The minerals present in kimberlites vary widely and can include from trace to predominance any of the following minerals: apatite, calcite, chlorite, diopside (pyroxene), magnetite, monticellite...

available online at http://meteoritics.org 1675 © The Meteoritical Society, 2006. Printed in USA. Breccia dikes and crater-related faults in impact craters on Mars: Erosion and exposure on the floor of a crater 75 km in diameter at the dichotomy boundary James W. HEAD* and John F. MUSTARD Department of Geological Sciences, Brown University, Providence, Rhode Island 02912, USA *Corresponding aut...

introduction mesgar iron occurrence is located in northwestern part of the central iran, 115 km south of zanjan. although there is a sequence of volcanic-pyroclastic rocks accompanied by iron mineralization, no detailed works had been conducted in the area. the present paper provides an overview of the geological framework, the mineralization characteristics, and the results of geochemical stud...

The Northparkes district, central New South Wales, hosts several economic Cu–Au deposits associated with discrete, thin, porphyry intrusive complexes emplaced in the Late Ordovician during formation of Macquarie Arc. recently discovered Two-Thirty Cu–Au–(Mo) prospect is a mineralised magmatic–hydrothermal breccia complex that hosted by moderately east-dipping Goonumbla Volcanic Complex on weste...

Introduction: The formation of impact related pseudotachylitic breccias and their occurrence in large impact structures such as Vredefort and Sudbury is still a matter of debate. The main formation processes that are currently considered – in the absence of large-scale fault/shear zones where massive friction melts could be generated-are shock melting, frictional melting and decompression melti...

Introduction: An Upper Eocene diamictite, unique in the Coastal Plain stratigraphy of east-central Georgia, has been described as an altered volcaniclastic deposit [1-4] resulting from widespread ashfall or pyroclastic flows [1,2]. While the breccia bed does appear strikingly similar to weathered silicic tuffs (Figure 1), previous authors have never speculated where the Late Eocene volcanic sou...

Large volumes of carbonate breccia occur in the late syn-rift and early post-rift deposits of the Billefjorden Trough, Central Spitsbergen. Breccias are developed throughout the Moscovian Minkinfjellet Formation and in basal parts of the Kazimovian Wordiekammen Formation. Breccias can be divided into two categories: (i) thick, cross-cutting breccia-bodies up to 200 m thick that are associated w...