SFifteen Rb/Sr and 40Ar/39Ar mineral ages were obtained on peraluminous, calcalkaline, transitional and alkaline late – Hercynian dykes intruding the Hercynian batholith in Northern and Central Sardinia. Ages and initial Sr isotopic ratios (Sri) closely mirror the subdivision into petrochemical groups and outline two tectonic domains with a different magmatic history. In the South, dyke intrusions are limited to peraluminous and high Sri, Calcalkaline products clustered between 298+- 5 and 289+- 4 Ma with Sri between 0.7164 and 0.7091. In the North, which underwent a significant exhumation and crustal thinning, the evolution took place from peraluminous (282+- 4 to 268+-4 Ma, 0.7100 to 0.7149) to low Sri calcalkaline (270+- 10 Ma, ca. 0.7060) to alkaline dykes (230+- 10 Ma, ca. 0.7040). The tectonic environment, thus, changed from orogenic to anorogenic continental.
Geochronology and Sr-isotope geochemistry of late Hercynian dykes from Sardinia.
VACCARO, Carmela;
1991
Abstract
SFifteen Rb/Sr and 40Ar/39Ar mineral ages were obtained on peraluminous, calcalkaline, transitional and alkaline late – Hercynian dykes intruding the Hercynian batholith in Northern and Central Sardinia. Ages and initial Sr isotopic ratios (Sri) closely mirror the subdivision into petrochemical groups and outline two tectonic domains with a different magmatic history. In the South, dyke intrusions are limited to peraluminous and high Sri, Calcalkaline products clustered between 298+- 5 and 289+- 4 Ma with Sri between 0.7164 and 0.7091. In the North, which underwent a significant exhumation and crustal thinning, the evolution took place from peraluminous (282+- 4 to 268+-4 Ma, 0.7100 to 0.7149) to low Sri calcalkaline (270+- 10 Ma, ca. 0.7060) to alkaline dykes (230+- 10 Ma, ca. 0.7040). The tectonic environment, thus, changed from orogenic to anorogenic continental.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
