The Mesoproterozoic Suwałki anorthosite massif (SAM) in NE Poland, intruded into a late Palaeoproterozoic domain in southeastern Fennoscandia, comprises anorthosite, Fe-Ti-V oxide ore deposits, gabbroic rocks and rapakivi-like granitoids. In the present study, a new set of age determinations on zircon grains from AMCG components (anorthosites and rapakivi granites) from different parts of the SAM massif, from granite veins cutting the AMCG rock suite, and from micro-coronas formed on Fe-Ti oxides, is presented. The new age results obtained using a SHRIMPIIe/MC change the previous interpretation (Re-Os NTIMS method on sulfides) that the SAM anorthosites were emplaced at ca 1.55 Ga. The new zircon SHRIMP ages indicate that anorthosites were intruded in several magmatic pulses culminating at ca. 1515 Ma and 1507 Ma. This is confirmed by single spot data and concordia ages of 1513 ± 6 Ma, 1509 ± 3 Ma and 1507 ± 3 Ma obtained for anorthosites. Similar single-spot peaks at 1515 Ma, 1509 Ma and 1496 Ma characterize rapakivi-type granites which also yielded concordia ages of 1513 ± 6 Ma, 1507 ± 6 Ma and 1499 ± 8 Ma. The SHRIMP data from the SAM anorthosites indicate an age of emplacement significantly younger than the ca 1.55 Ga age determined previously, and coeval to ages obtained for rapakivi granite. Both rock types contain entrained antecrysts, reflecting a two-step crystallization in a deep-seated magma chamber and continuous crystallization during the rising of the melt and incremental emplacement of the SAM. Abundant granitic aplites and pegmatites in sharp contact with the host AMCG rocks define a time frame for the entire SAM solidification. The crystallization ages of individual veins ranging between 1489 ± 6 Ma and 1475 ± 5 Ma are clearly older than cooling ages previously obtained by Ar-Ar and K-Ar methods. Microgranites with numerous inherited zircon cores were generated by re-melting of the local sources, including late Paleoproterozoic ca 1.83 Ga crust and SAM related rocks, within a shallow felsic magma chamber. Finally, zircon coronas on Fe-Ti oxides ilmenite grains record subsolidus ilmenite exsolution processes (from ilmenite) occurring simultaneously with the crystallization of the aplite and pegmatite veins.

位于波兰东北部的中元古代 Suwałki 斜长岩地块 (SAM)，侵入到 Fennoscandia 东南部的晚古元古代域，包括斜长岩、Fe-Ti-V 氧化物矿床、辉长岩和类 rapakivi 花岗岩。在本研究中，对来自 SAM 地块不同部分的 AMCG 组分（斜长岩和 rapakivi 花岗岩）、切割 AMCG 岩石套件的花岗岩脉以及在 Fe-Ti 上形成的微冠的锆石颗粒进行了一组新的年龄测定氧化物，介绍。使用 SHRIMPIIe/MC 获得的新年龄结果改变了之前的解释（关于硫化物的 Re-Os NTIMS 方法），即 SAM 斜长岩位于约 1.55 Ga。新的锆石 SHRIMP 年龄表明斜长岩被侵入到几个岩浆脉冲中，在约 1515 毫安和 1507 毫安。单点数据和从斜长岩中获得的 1513 ± 6 Ma、1509 ± 3 Ma 和 1507 ± 3 Ma 的协和年龄证实了这一点。1515 Ma、1509 Ma 和 1496 Ma 处类似的单点峰表征了 rapakivi 型花岗岩，其也产生了 1513 ± 6 Ma、1507 ± 6 Ma 和 1499 ± 8 Ma 的协和年龄。来自 SAM 斜长岩的 SHRIMP 数据表明，其侵位年龄明显小于先前确定的约 1.55 Ga 年龄，并且与 rapakivi 花岗岩的年龄相同。两种岩石类型都包含夹带的前晶，反映了在深部岩浆房中的两步结晶以及在熔融物上升和地表岩层逐渐侵位过程中的连续结晶。与主 AMCG 岩石急剧接触的丰富的花岗岩和伟晶岩定义了整个 SAM 凝固的时间框架。单个脉的结晶年龄介于 1489 ± 6 Ma 和 1475 ± 5 Ma 之间，显然比以前通过 Ar-Ar 和 K-Ar 方法获得的冷却年龄要早。具有众多继承锆石核的微花岗岩是通过在浅长英质岩浆房内重新熔化当地来源产生的，包括晚古元古代约 1.83 Ga 地壳和 SAM 相关岩石。最后，Fe-Ti 氧化物钛铁矿颗粒上的锆石冠记录了亚固相钛铁矿出溶过程（来自钛铁矿），与亚晶和伟晶岩脉的结晶同时发生。包括晚古元古代约 1.83 Ga 地壳和 SAM 相关岩石，位于浅长英质岩浆房内。最后，Fe-Ti 氧化物钛铁矿颗粒上的锆石冠记录了亚固相钛铁矿出溶过程（来自钛铁矿），与亚晶和伟晶岩脉的结晶同时发生。包括晚古元古代约 1.83 Ga 地壳和 SAM 相关岩石，位于浅长英质岩浆房内。最后，Fe-Ti 氧化物钛铁矿颗粒上的锆石冠记录了亚固相钛铁矿出溶过程（来自钛铁矿），与亚晶和伟晶岩脉的结晶同时发生。