EN I This #TuesdayFieldMemory is a pseudotachylite from the Juru shear zone (PB, Brazil) showing the main vein (centimetric) containing quartz and feldspar fractured clasts. From the main vein, injection veins oriented obliquely to its configuration are present, in which relitic grains of recrystallized quartz are observed. Contribution by Gustavo Viegas @lgviegas This rock andContinue reading “[TFM] Pseudotachylite from the Juru shear zone (PB, Brazil)”
Tag Archives: Brazil
[TST] Ultraclasite from the Pernambuco shear zone (PE, Brazil)
EN I Our #ThinSectionThursday this week is an ultracataclasite from the eastern Pernambuco shear zone (PE, Brazil) containing heterogeneous fragments of ultramylonite, plagioclase and quartz. Recrystallised quartz aggregates are observed at the contact of the ultracataclasite with its host granite. (Lambda plate inserted). This rock and its geological context will be discussed on our nextContinue reading “[TST] Ultraclasite from the Pernambuco shear zone (PE, Brazil)”
[Article] Unravelling the protracted U-Pb zircon geochronological record of high to ultrahigh temperature metamorphic rocks: Implications for provenance investigations
EN I Our article, “Unravelling the protracted U-Pb zircon geochronological record of high to ultrahigh temperature metamorphic rocks: implications for provenance investigations“, is already available on the Geoscience Frontiers website! We discuss the possible causes of bias in the analysis of U-Pb ages in rocks that underwent extreme metamorphic conditions and propose a workflow inContinue reading “[Article] Unravelling the protracted U-Pb zircon geochronological record of high to ultrahigh temperature metamorphic rocks: Implications for provenance investigations”
[Article] Zircon petrochronology reveals the moderately juvenile signature of a diatexite from the boundary zone between the Brasília and Ribeira orogens (SE Brazil): Relict of a Tonian arc?
EN | How fun is to find an exception to the rule?In our contribution we report a biotite-bearing granitic leucosome from Socorro-Guaxupé nappe of the Southern Brasília orogen with an anomalous juvenile-like signature.The zircon extracted from this rock yield a protracted spread of U–Pb ages from ca. 890 Ma to ca. 540 Ma and theContinue reading “[Article] Zircon petrochronology reveals the moderately juvenile signature of a diatexite from the boundary zone between the Brasília and Ribeira orogens (SE Brazil): Relict of a Tonian arc?”
[Article] Implications of the dominant LP–HT deformation in the Guanhães Block for the Araçuaí West-Congo Orogen evolution
EN | For far too long has the Guanhães Block been viewed as an empty square in the evolutionary models of the Araçuaí-West-Congo Orogen. A new publication in Gondwana Research uses petrochronological strategies with dating of multiple mineral phases, traditional thermobarometry and phase-diagram modeling to understand the conditions in which the main pervasive foliation wasContinue reading “[Article] Implications of the dominant LP–HT deformation in the Guanhães Block for the Araçuaí West-Congo Orogen evolution”
[Tips] Zircon role in Petrochronology
EN | Zircon is a petrochronology superstar and here is why: besides being a very robust chronometer, it can record different geological conditions during the formation of a rock. For example, are you aware that zircon morphology may constrain the temperature in which it was crystallized? Within this context, Araujo et al. (2020) explored zirconContinue reading “[Tips] Zircon role in Petrochronology”
[Article] The missing piece of the Paranapanema block in the Guaxupé nappe (Southernmost Brasília orogen)
EN | The Paranapanema block constitutes an important piece in paleogeographical reconstructions. However, few direct information about it in the Southernmost Brasília orogen is available as the block has been covered since the Cretaceous by the Parana basin. Surprisingly, two very similar samples of Opx-Cpx-Hbl banded granulites separated by 5km have shown strongly different U-PbContinue reading “[Article] The missing piece of the Paranapanema block in the Guaxupé nappe (Southernmost Brasília orogen)”
[TST] Late-magmatic fluid induced alteration in the Itaporé batholith rocks
EN | Late-magmatic fluid induced alteration is outstandingly marked in the Itaporé batholith rocks: This evolution in the alteration degree is evidenced by siderophyllite (Bt) to phengite (Ph) to muscovite (Ms) transitions. The intense degree of alteration in the two-mica granite (a) and the muscovite leucogranite (b) result in a significant deviation from the parentalContinue reading “[TST] Late-magmatic fluid induced alteration in the Itaporé batholith rocks”
PETROCHRONICS 