Kimberlites and related rocks are the focus of research and exploration in the Alto Paranaiba Igneous Province (APIP; Brazil) due to their potential correlation with adjacent diamond fields. New U-Pb perovskite ages were obtained using recommended protocols for error propagation and data interpretation. Despite the utility of perovskites for dating, their incorporation of significant common-Pb (common-Pb of new APIP data: 52–84 % for in situ analyses, 75–95 % for TIMS concentrate analyses) limits the age resolution of this dating approach. Consequently, the APIP U-Pb ages neither confirm nor discredit previously proposed geodynamic models that invoke age progression or distinct magmatic episodes. Comparing the new ID-TIMS and LA-ICP-MS ages of the same intrusions, the LA-ICP-MS data have lower uncertainties, largely due to accessing a greater spread in common-Pb, improving regressions, and tend to yield older ages. For perovskite grains collected from weathering profiles, we found evidence of Pb-loss. This process leads to higher uncertainties in individual analyses, increased data scatter, and consequently higher uncertainties in age estimates. For fresh samples with different degrees of crustal contamination from a single intrusion, we found an indication of some variability in 207Pb/206Pb and 238U/206Pb ratios of the perovskite data, with a tendency towards older ages for more contaminated sample. For almost fresh intrusions with geochemically and isotopically similar mantle sources, related to the same event and in a close geographic area, we prefer to use a unique local 207Pb/206Pb ratio as anchoring for each Tera-Wasserburg plot. This approach is particularly preferred when perovskite data of an intrusion are too clustered and the 207Pb/206Pb ratio from the unanchored T-W differs from that predicted from theoretical Pb-isotope evolution model. Despite the high-common Pb in APIP perovskite crystals, our new data using these strategies clearly indicate that APIP magmatism is restricted to the Cretaceous, with most cases crystallized in Upper Cretaceous, but some from Early Cretaceous, such as the diamondiferous occurrence of Catalão-1b (120.6 ± 6.7 Ma). Different triggers of APIP magmatism are related to both episodes, mainly attributed to supercontinent break-up stages.

中文翻译：

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稳健的方法，棘手的材料：从白垩纪巴西金伯利岩中测年高共铅钙钛矿的挑战


金伯利岩和相关岩石是上巴拉那巴火成岩省 （APIP;Brazil） 的 S Alpha S Capital，因为它们与相邻的钻石矿场可能存在相关性。使用推荐的误差传播和数据解释方案获得新的 U-Pb 钙钛矿年龄。尽管钙钛矿可用于测年，但它们掺入了重要的 common-Pb（新 APIP 数据的 common-Pb：原位分析为 52-84 %，TIMS 浓缩分析为 75-95%）限制了这种测年方法的年龄分辨率。因此，APIP U-Pb 年龄既没有确认也没有诋毁以前提出的地球动力学模型，这些模型引发了年龄进展或不同的岩浆事件。比较相同侵入的新 ID-TIMS 和 LA-ICP-MS 年龄，LA-ICP-MS 数据具有较低的不确定性，这主要是由于访问了更大的 Common-Pb 分布，改善了回归，并且往往产生较老的年龄。对于从风化剖面中收集的钙钛矿颗粒，我们发现了 Pb 损失的证据。这个过程导致个体分析的不确定性更高，数据分散增加，因此年龄估计的不确定性更高。对于单次侵入导致不同程度地壳污染的新鲜样品，我们发现钙钛矿数据的 207Pb/206Pb 和 238U/206Pb 比率存在一些变化，并且污染较多的样品有老化的趋势。对于具有地球化学和同位素相似地幔源的近新侵入体，与同一事件相关且位于邻近的地理区域，我们更喜欢使用独特的局部 207Pb/206Pb 比率作为每个 Tera-Wasserburg 图的锚定。 当侵入体的钙钛矿数据过于聚集并且来自未锚定 T-W 的 207Pb/206Pb 比率与理论 Pb-同位素演化模型预测的比率不同时，这种方法特别可取。尽管 APIP 钙钛矿晶体中的铅含量很高，但我们使用这些策略的新数据清楚地表明，APIP 岩浆作用仅限于白垩纪，大多数情况在上白垩纪结晶，但也有一些来自早白垩纪，例如 Catalão-1b 的钻石矿床（120.6 ± 6.7 马）。APIP 岩浆作用的不同触发因素与这两种事件有关，主要归因于超大陆破裂阶段。