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Gramscatho-Mylor facies relationships; Hayle, south Cornwall

REA Auditado

The Gramscatho Group and the Mylor Slate Formation are the two main lithostratigraphic groups that outcrop in south Cornwall. Their mutual relationship has been disputed for some time because of poor palaeontological control and the effects of polyphase deformation. A study of the lithofacies exposed around Hayle suggests a breakdown of the generally valid lithostratigraphy. A transitional zone occurs in which Gramscatho and Mylor lithofacies are seen to be contemporaneous and are interpreted as a rise-slope association.

Tema: general: 

• Ingeniería y Ciencias Aplicadas›Ingeniería›Metalurgia y Mineralogía; Ingeniería Mineral

Field excursion to the Gramscatho Group of south Cornwall, 5th January 1991

REA Auditado

Tema: general: 

• Ingeniería y Ciencias Aplicadas›Ingeniería›Metalurgia y Mineralogía; Ingeniería Mineral

Tectonic evolution of the Plymouth Bay Basin

REA Auditado

A synthesis of offshore seismic data in the Plymouth Bay and Western Approaches, and onshore basement structures and mineralisation history has allowed new constraints to be placed on the structural evolution of the late Carboniferous- Triassic Plymouth Bay Basin. These data have been combined to produce a model for the late- and post- Variscan tectonics of the Plymouth Bay area. Additional controls on the timing and magnitude of Variscan uplift and late-Variscan low-angle extensional deformation onshore are used to infer a late Carboniferous age for the earliest basin fill.

Tema: general: 

• Ingeniería y Ciencias Aplicadas›Ingeniería›Metalurgia y Mineralogía; Ingeniería Mineral

Late- to post-Variscan extensional tectonics in south Cornwall

REA Auditado

Faults which post-date Variscan contractional deformation are ubiquitous in south Cornwall. Three broad
geometric/kinematic types can be defined. The first type comprises low angle (dip <45°) extensional faults which exhibit listric or ramp
and flat geometries and may display complex arrangements of secondary faults and folds in their hangingwalls. In some instances they
host elvans and "mainstage" magmatic-hydrothermal lodes (more rarely lamprophyres).

Tema: general: 

• Ingeniería y Ciencias Aplicadas›Ingeniería›Metalurgia y Mineralogía; Ingeniería Mineral

Field excursion to study Meadfoot Group sedimentation, magmatism and tectonics, 4th January 1995

REA Auditado

Tema: general: 

• Ingeniería y Ciencias Aplicadas›Ingeniería›Metalurgia y Mineralogía; Ingeniería Mineral

Late Variscan structures on the coast between Perranporth and St. Ives, Cornwall

REA Auditado

Structural mapping of the coast between Perranporth and St. Ives has shown that two generations of north-north-west verging Variscan
convergence related structures (D1 and D2) are post-dated by a diverse range of structures showing top to the south-east sense of shear. These D3
structures are represented by the coeval development of ductile zones of distributed shear, brittle-ductile detachments and brittle south-east
dipping listric extensional faults.

Tema: general: 

• Ingeniería y Ciencias Aplicadas›Ingeniería›Metalurgia y Mineralogía; Ingeniería Mineral

Late- to post-Variscan structures on the coast between Penzance and Pentewan, south Cornwall

REA Auditado

The occurrence of two generations (D1/D2) of folds and cleavage, compatible with a top to the north-north-west sense of shear during Variscan convergence is confirmed. A subsequent change in the stress regime (sigma(1) approximate to vertical, sigma(3) approximate to north-north-west-south-south-east) brought about the extensional reactivation of convergence-related features. The resultant D3 structures are diverse and include zones of distributed shear within the footwall of the Carrick Thrust, together with detachments and high angle brittle extensional faults within the hangingwall.

Tema: general: 

• Ingeniería y Ciencias Aplicadas›Ingeniería›Metalurgia y Mineralogía; Ingeniería Mineral

A re-interpretation of the internal structure of the Lizard complex ophiolite, south Cornwall.

REA Auditado

Previous models for the tectonic-stratigraphy of the Lizard complex ophiolite have proposed three thrust-bounded units. However, our studies indicate that post-obduction extensional faulting may have exerted a hitherto unrecognised effect on the present distribution of lithologies. Field and previously published geophysical evidence suggest that the uppermost tectonic unit (the Crousa Downs Unit) represents the downfaulted upper levels of the Goonhilly Downs Unit. Deformed lithologies previously thought to be part of the Goonhilly Downs Unit are reassigned to the underlying Basal Unit.

Tema: general: 

• Ingeniería y Ciencias Aplicadas›Ingeniería›Metalurgia y Mineralogía; Ingeniería Mineral

Is there gold mineralization associated with the Carrick thrust?

REA Auditado

Tema: general: 

• Ingeniería y Ciencias Aplicadas›Ingeniería›Metalurgia y Mineralogía; Ingeniería Mineral

Alteration and vein mineralisation within the Lizard complex, south Cornwall: constraints on the timing of serpentinisation.

REA Auditado

Two distinct episodes of serpentinisation have been identified within the peridotites of the Lizard complex. The first episode (primary serpentinisation) is represented by the complex and pervasive hydration of the Lizard peridotite. The second (later) episode is characterised by a pale to dark green, pseudo-fibrous mixture of lizardite and chrysotile that is restricted to fractures (vein serpentine). Mineralised north-north-west and east-north-east trending fault zones contain fragments of vein serpentine generated during this second episode.

Tema: general: 

• Ingeniería y Ciencias Aplicadas›Ingeniería›Metalurgia y Mineralogía; Ingeniería Mineral