Fifteen Rb/Sr and mArPAt 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 (Sr^ 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 Sr; calcalkaline products clustered between 298 ± 5 and 289 ± 4 Ma with S^ between .7164 and .7091. In the North, which underwent a significant exhumation and crustal thinning, the evolution took place from peraluminous (282 ± 4 to 268 ± 4 Ma, .7100 to .7149) to low Srt calcalkaline (270 ± 10 Ma, ca. .7060) to alkaline dykes (230 ± 10 Ma, ca. .7040). The tectonic environment, thus, changed from orogenic to anorogenic continental.
Geochronology and Sr isotope geochemistry of Late-Hercynian dykes from Sardinia
ODDONE, MASSIMO;
1991-01-01
Abstract
Fifteen Rb/Sr and mArPAt 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 (Sr^ 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 Sr; calcalkaline products clustered between 298 ± 5 and 289 ± 4 Ma with S^ between .7164 and .7091. In the North, which underwent a significant exhumation and crustal thinning, the evolution took place from peraluminous (282 ± 4 to 268 ± 4 Ma, .7100 to .7149) to low Srt calcalkaline (270 ± 10 Ma, ca. .7060) to alkaline dykes (230 ± 10 Ma, ca. .7040). The tectonic environment, thus, changed from orogenic to anorogenic continental.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
