Comment on “Rheic Ocean ophiolitic remnants in southern Iberia questioned by SHRIMP U‐Pb zircon ages on the Beja‐Acebuches amphibolites” by A. Azor et al.

Pin, Christian; Rodríguez, Javier Caride

doi:10.1029/2009tc002495

Cited by 15 publications

(3 citation statements)

References 22 publications

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“…If so, the Rb-Sr WR isochron (Oberc-Dziedzic et al, 1996) should not be dis carded too quickly. Ad mit tedly, the Rb-Sr WR ap proach can not com pete in terms of pre ci sion with the U-Pb tech nique, and it is sub ject to many po tential pit falls which may lead to in ac cu rate results, but U-Pb dat ing is not free of pit falls ei ther, a most crit i cal one be ing the dif fi culty in as sess ing the true de gree of dis cor dance when us ing in situ meth ods (e.g., Pin and Ro dri guez, 2009).…”

Section: Sample 300 V Medium-grained Granitementioning

confidence: 99%

Variscan granitoid plutonism in the Strzelin Massif (SW Poland): petrology and age of the composite Strzelin granite intrusion

Oberc-Dziedzic

Kryza

et al. 2013

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Oberc-Dziedzic T., Kryza R., Pin C. and Madej S. (2013) Variscan granitoid plutonism in the Strzelin Mas sif (SW Po land): petrol ogy and age of the com pos ite Strzelin gran ite in tru sion. Geo log i cal Quar terly, 57 (2): 269-288, doi: 10.7306/gq.1083Pet ro log i cal data and re cently pub lished U/Pb zir con SHRIMP ages re veal a pro tracted Variscan mag matic evo lu tion in the Strzelin Mas sif (SW Po land), with three main stages of granitoid plutonism: 1 -tonalitic I, 2 -granodioritic and 3 -tonalitic II/gra nitic. The granitoids of the sec ond and third stages form the Strzelin in tru sion that is com posed of three va ri et ies: medium-grained bi o tite gran ite, fine-grained bi o tite gran ite and fine-grained bi o tite-mus co vite gran ite. New SHRIMP data show that the me dium-grained and fine-grained bi o tite gran ites com prise dif fer ent zir con pop u la tions that re flect com plex and prolonged plutonic pro cesses. Two dis tinct mag matic events seem to be rep re sented by well-de fined zir con pop u la tions with ap par ent 206 Pb/ 238 U ages of 303 ± 2 Ma in the me dium-grained bi o tite gran ite, and 283 ± 8 Ma in the fine-grained bi o tite granite. These dates, how ever, do not nec es sar ily re flect the true mag matic ages, pos si bly be ing "re ju ve nated" by ra dio genic lead loss in zir cons (im pos si ble to re solve based on rou tine SHRIMP data). Based on field ev i dence, the third va ri ety, the bi otite-mus co vite gran ite, post dates both types of bi o tite gran ites. The petrographic and geo chem i cal fea tures, in clud ing Nd isotope sig na ture, along with var i ous zir con in her i tance pat terns and ages, sug gest that the pa ren tal mag mas of the three gran ites orig i nated from dif fer ent crustal sources and were emplaced dur ing three suc ces sive mag matic pulses.

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Section: Sample 300 V Medium-grained Granitementioning

confidence: 99%

Variscan granitoid plutonism in the Strzelin Massif (SW Poland): petrology and age of the composite Strzelin granite intrusion

Oberc-Dziedzic

Kryza

et al. 2013

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“…We acknowledge the invaluable opportunity that the comment by Pin and Rodríguez [2009] offers us in order to corroborate the conclusions of our paper and clarify our analytical methods. Our response will be focused on aspects concerning (1) the accuracy of our SHRIMP analyses, (2) sample distribution, (3) sample geochemistry, and (4) geological implications of the ages.…”

Section: Introductionmentioning

confidence: 56%

Reply to comment by C. Pin and J. Rodríguez on “Rheic Ocean ophiolitic remnants in southern Iberia questioned by SHRIMP U‐Pb zircon ages on the Beja‐Acebuches amphibolites”

et al. 2009

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“…Moreover, on the basis of reflection seismic data, magmatic rocks have been interpreted to occur in the upper crust of SW Iberia [ Simancas et al , 2003; Carbonell et al , 2004; Schmelzbach et al , 2008; Palomeras et al , 2009, 2011]. The tectonic interpretation of this significant magmatic intraorogenic event is open to debate: it might be a hot spot related to some type of mantle plume impinging on SW Iberia and the neighboring Canadian Maritimes [ Simancas et al , 2006] or it might be due to orogenic slab breakoff [ Pin and Rodríguez , 2009].…”

Section: Geological Settingmentioning

confidence: 99%

Shear wave modeling and Poisson's ratio in the Variscan Belt of SW Iberia

Palomeras

Carbonell

Ayarza

et al. 2011

Geochem. Geophys. Geosyst.

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[1] In 2003 two wide-angle reflection/refraction seismic transects were acquired in the Variscan Belt of SW Iberia. The approximately 250 and 300 km long, dense trace spacing transects revealed clear S wave arrivals in the shot gathers recorded by vertical component sensors in both transects. First S wave arrivals (Sg) and Moho reflections (SmS) are the most prominent phases that can be correlated from shot to shot. Sg is observed up to relatively large offsets and constrains the upper and middle crust S wave velocities. The SmS is seen from offset 0 (18 s twtt) to 150 km offset, where it intercepts first S wave arrivals (Sg). The upper mantle refracted phase (Sn) is difficult to recognize, although PmS/SmP converted phases can be identified. Using a 2-D ray tracing approach, two S wave velocity models for the crust of SW Iberia were obtained. These S wave velocity models complement the previous P wave velocity models and provide us with relatively well resolved Poisson's ratio crustal sections for SW Iberia. The resulting Poisson's ratio models present differences between tectonic zones at upper and middle crustal depths, thus supporting the existence of different tectonic zones prior to the Variscan collision. The most noteworthy feature is the high Poisson's ratio value (over 0.28) coincident with high P wave velocity areas (over 6.8 km/s) at midcrustal depths. In order to constrain the possible crustal composition, P wave velocities and Poisson's ratios have been compared with published laboratory measurements on different crustal rock types. This comparison indicates that the high P wave velocity and Poisson's ratios are compatible with a mixture of mafic to ultramafic rock types alternating with felsic ones. This result is consistent with the existence of mafic layered bodies in the middle crust, in the same way that has been suggested by previous works in this area.

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Comment on “Rheic Ocean ophiolitic remnants in southern Iberia questioned by SHRIMP U‐Pb zircon ages on the Beja‐Acebuches amphibolites” by A. Azor et al.

Cited by 15 publications

References 22 publications

Variscan granitoid plutonism in the Strzelin Massif (SW Poland): petrology and age of the composite Strzelin granite intrusion

Variscan granitoid plutonism in the Strzelin Massif (SW Poland): petrology and age of the composite Strzelin granite intrusion

Reply to comment by C. Pin and J. Rodríguez on “Rheic Ocean ophiolitic remnants in southern Iberia questioned by SHRIMP U‐Pb zircon ages on the Beja‐Acebuches amphibolites”

Shear wave modeling and Poisson's ratio in the Variscan Belt of SW Iberia

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