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4 The diatremes of the Eifel

Pre-conference fieldtrip: 07.08. - 10.08
Post-conference fieldtrip: 16.08. – 18.08

 



4.1 Pre-Conference Field Trip

 

Field guides:
Volker Lorenz
Bernd Zimanowski

Departure/Arrival: Frankfurt / Frankfurt

Approximate costs: 460 €

Min. participants: 15
Max. participants
: ca. 30


Abstract:

The main topic of the field trip will cover the classic West Eifel
Maar volcanoes and the scoria cones associated with them of the Quarternary West Eifel Volcanic Field. Kimberlite pipes form the subterranean part of kimberlite maar-diatreme volcanoes. Because of their age and erosion, however, kimberlite pipes have lost their former surface features such as their tephra ring and their relationship with topography, near-surface tectonic structures, and drainage. The classic Quarternary maars of the Westeifel in contrast provide insight into the eruptive and volcanotectonic evolution of maar-diatreme volcanoes which might also have been controlling the formation of kimberlite pipes.
The West Eifel volcanic field consists of c. 200 scoria cones and c. 75 maars. About 2/3 of the scoria cones are underlain by a small maar crater. The Devonian country rocks and the characteristics of the many rather thin maar tephra beds will be studied as well as the relationship of the maars and scoria cones with the topography and hydrogeology (i.e. with hydraulically active fracture zones in the Devonian hard rocks). Some maar tephra are well known for their spinel lherzolite nodules. Originally, the West Eifel maars - they are associated with the eruption of nephelinite, leucitite, basanite, and tephrite magmas - were considered to be the result of explosive release of juvenile volatile phases. Since almost 40 years, however, the maars have been increasingly realized to be phreatomagmatic in origin as are all other well-studied maars world-wide. We will also discuss the relationship between maar craters and their diatremes which is very relevant for understanding diatremes in general, including kimberlite pipes, and commodities potentially contained in diatremes. In addition, the Laacher See volcano, which erupted c. 12,900 years ago, and one impressive outcrop in its phonolitic phreatomagmatic and magmatic tephra deposits will be visited in the Quaternary East Eifel Volcanic Field.

 



4.2 Post-Conference Field Trip

Field guides:
Volker Lorenz
Bernd Zimanowski

Departure/Arrival: Frankfurt / Frankfurt

Approximate costs of the field trip: 360 €

Min. participants: 15
Max. participants
: ca. 30


Abstract:

The main topic of the field trip will cover the classic West Eifel
Maar volcanoes and the scoria cones associated with them. As kimberlite pipes form the subterranean part of kimberlite maar-diatreme volcanoes and, because of their age and erosion, have lost their former surface features such as their tephra ring and relationship with topography, tectonic structures and drainage the classic Pleistocene maars of the Westeifel provide insight into the eruptive and volcano-tectonic processes of maar-diatreme volcanoes which might have been controlling also the formation of kimberlite pipes.
The West Eifel volcanic field consists of c. 200 scoria cones and c. 70 maars. About 2/3 of the scoria cones are underlain by a small maar crater. The Devonian country rocks and the characteristic of the many rather thin maar tephra beds will be studied as well as the relationship of the maars and scoria cones with the topography and hydrogeology (i.e. with hydraulically active fracture zones in the hard rocks). Some maar tephra are well known for their spinel lherzolite nodules. Originally the West Eifel maars - they are associated with nephelinites, leucitites, basanites, and tephrites - were considered to be the result of explosive release of juvenile volatile phases. Since almost 40 years, however, the maars have been increasingly realized to be phreatomagmatic in origin as are all other well-studied maars world-wide. We will also discuss the relationship between maar craters and diatremes which is very relevant for understanding diatremes, including kimberlite pipes, and commodities potentially contained in diatremes. In addition, the Laacher See volcano, which erupted c. 12,900 years ago, and one impressive outcrop in its phonolitic phreatomagmatic and magmatic tephra deposits will be visited in the East Eifel Volcanic Field.