Paleomagnetism of Jurassic and Cretaceous rocks in central Patagonia: a key to constrain the timing of rotations during the breakup of southwestern Gondwana?

Geuna, Silvana Evangelina; Somoza, Rubén; Vizán, Haroldo; Figari, Eduardo G.; Rinaldi, Carlos

doi:10.1016/s0012-821x(00)00198-9

Cited by 46 publications

(29 citation statements)

References 42 publications

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“…Moreover, recent plate kinematics analysis indicates that the western Gondwana paleogeography may be reconstructed without appealing to a microplate-like behaviour for the Malvinas/Falkland Islands (Eagles and Vaughan, 2009). These observations favor the alternative scenario where the clockwise tectonic rotation found in the island is part of a widespread rotational deformation in southern South America during the supercontinent breakup, as it is supported by pre-mid-Cretaceous clockwise rotations found in several Patagonian areas south of the Gastre zone (Geuna et al, 2000;Somoza et al, 2008).…”

Section: Implications For Models Of Western Gondwana Breakupsupporting

confidence: 53%

Anisotropy of magnetic susceptibility study in two classical localities of the Gastre Fault System, central Patagonia

Zaffarana

Luchi

Somoza

et al. 2010

Journal of South American Earth Sciences

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Section: Implications For Models Of Western Gondwana Breakupsupporting

confidence: 53%

Anisotropy of magnetic susceptibility study in two classical localities of the Gastre Fault System, central Patagonia

Zaffarana

Luchi

Somoza

et al. 2010

Journal of South American Earth Sciences

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“…15). The 1-MIS PP agrees with PPs of similar and younger ages from the Central Paraná Magmatic Province (132133 Ma; Alva-Valdivia et al, 2003), Central Alkaline Province, Paraguay (127130 Ma; Ernesto et al, 1996), Sierras Pampeanas (130 Ma; Geuna and Vizán, 1998), Baqueró Group (119 Ma; Somoza et al, 2005) and Los Adobes Formation (112130 Ma; Geuna et al, 2000), (PPs 6,7,8,10 and 11,Table 5, Fig. 15).…”

Section: Paleointensity Determinationsupporting

confidence: 72%

Paleosecular variation and absolute geomagnetic paleointensity records retrieved from the Early Cretaceous Posadas Formation (Misiones, Argentina)

et al. 2011

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The Early Cretaceous may be considered a key period for understanding the evolution of the Earth's magnetic field. Some still unsolved problems are related to the mode of paleosecular variation (PSV) of the Earth's magnetic field before and during the Cretaceous Normal Superchron. We report here a detailed rock-magnetic, paleomagnetic and paleointensity investigation from 28 lava flows (331 standard paleomagnetic cores) collected in the Argentinean part of the Parana Flood Basalts (Formation Posadas) in order to contribute to the study of PSV during the early Cretaceous and to obtain precise Cretaceous paleomagnetic pole positions for stable South America. The average paleofield direction is precisely determined from 26 sites, which show small within-site dispersion and high directional stability. Five sites show evidences for the self-reversal of thermoremanent magnetization. 23 sites yielded normal polarity magnetization and only 3 are reversely magnetized. Moving windows averages were used to analyze the sequential variation of virtual geomagnetic pole's (VGP) axial positions. Interestingly, the axial average VGP path traces an almost complete cycle around the geographical pole and passes near the location of all previously published Paraná Magmatic Province poles. Both paleomagnetic poles and average VGP paths are significantly different from the pole position suggested by fixed hotspot reconstructions, which may be due to true polar wander or the hotspot motion itself. Only 15 samples from 5 individual basaltic lava flows, yielded acceptable paleointensity estimates. The site mean paleointensities range from 25.2  2.2 to 44.0  2.2 T. The virtual dipole moments (VDMs) range from 4.8 to 9.9  10 22 Am 2 . This correspond to a mean value of 7.7  2.1  10 22 Am 2 which is 96% of the present day geomagnetic field strength. These intensities agree with the relatively high values already reported for Early Cretaceous, which are consistent with some inferences from computer simulations previously published. Continuation of LATINMAG Special Issue #4, Stud. Geophys. Geod., 54 (2010) M. Mena et al. 280 Stud. Geophys. Geod., 55 (2011) K e y w o r d s :

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“…Two anonymous referees are acknowledged for their constructive criticism. (Geuna et al, 2000). ** Location of South American paleomagnetic pole predicted from fixed hotspot rotations (Muller et al, 1993).…”

Section: Sitementioning

confidence: 99%

Paleomagnetism of early cretaceous arapey formation (Northern Uruguay)

et al. 2010

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We report detailed rock-magnetic and paleomagnetic directional data from 35 lava flows (302 standard paleomagnetic cores) sampled in the Central-Northern region of Uruguay in order to contribute to the study of the paleosecular variation of the Earth's magnetic field during early Cretaceous and to obtain precise Cretaceous paleomagnetic pole positions for stable South America. The average unit direction is rather precisely determined from 29 out of 35 sites. All A 95 confidence angles are less than 8°, which points to small within-site dispersion and high directional stability. Normal polarity magnetizations are revealed for 19 sites and 10 are reversely magnetized. Two other sites yield well defined intermediate polarities. The mean direction, supported by a positive reversal test is in reasonably good agreement with the expected paleodirection for Early Cretaceous stable South America and in disagreement with a 10° clockwise rotation found in the previous studies. On the other hand, paleomagnetic poles are significantly different from the pole position suggested by hotspot reconstructions, which may be due to true polar wander or the hotspot motion. Our data suggest a different style of secular variation during (and just before) the Cretaceous Normal Superchron and the last 5 Ma, supporting a link between paleosecular variation and reversal frequency. K e y wo r d s : paleosecular variation, Cretaceous paleomagnetic poles, Paraná Magmatic Province, Uruguay M.C. Solano et al. 534 Stud. Geophys. Geod., 54 (2010)

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Paleomagnetism of Jurassic and Cretaceous rocks in central Patagonia: a key to constrain the timing of rotations during the breakup of southwestern Gondwana?

Cited by 46 publications

References 42 publications

Anisotropy of magnetic susceptibility study in two classical localities of the Gastre Fault System, central Patagonia

Anisotropy of magnetic susceptibility study in two classical localities of the Gastre Fault System, central Patagonia

Paleosecular variation and absolute geomagnetic paleointensity records retrieved from the Early Cretaceous Posadas Formation (Misiones, Argentina)

Paleomagnetism of early cretaceous arapey formation (Northern Uruguay)

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