The present of Proterozoic detrital zircons indicate that the Songpan-Ganzi terrane is presumably floored with Precambrian basement rocks.
It is mainly composed of Triassic turbidite, which is intruded by many granitoid bodies.
It is obvious that the composition, sources and time of the granitic magma are very important for studing the basement and tectonic evolution of the Songpan-Ganzi terrane.
This paper reports some SHRIMP U-Pb dating results for zircons from granitoids in the Songpan-Ganzi terrane.
U/Pb dating is accomplished by laser-ablation ICP-MS in a small pit on the exterior of the crystal, and He dates are then determined on the bulk grain by conventional laser-heating and dissolution techniques. We present a method for estimating the extent of resetting of each grain and the thermal history of the sample, based on coupled (U-Th)/(He-Pb) age patterns among all the grains.
We present examples from Mesozoic aeolian sandstones, both modern and Paleogene fluvial sediments, and active margin turbidite assemblages from the Cascadia and Kamchatka margins. AB - Geochronology and thermochronology on detrital material provides unique constraints on sedimentary provenance, depositional ages, and orogenic evolution of source terrains.