The 1.87–1.84 Ga Black Hills dike swarm of the Kalahari craton (South Africa) is coeval with several regional magmatic provinces used here to resolve the craton's position during Columbia assembly. We report a new 1850 ± 4 Ma (U-Pb isotope dilution–thermal ionization mass spectrometry [ID-TIMS] on baddeleyite) crystallization age for one dike and new paleomagnetic data for 34 dikes of which 8 have precise U-Pb ages. Results are constrained by positive baked-contact and reversal tests, which combined with existing data produce a 1.87–1.84 Ga mean pole from 63 individual dikes. By integrating paleomagnetic and geochronological data sets, we calculate poles for three magmatic episodes and produce a magnetostratigraphic record. At 1.88 Ga, the Kalahari craton is reconstructed next to the Superior craton so that their ca. 2.0 Ga poles align. As such, magmatism forms part of a radiating pattern with the coeval ca. 1.88 Ga Circum-Superior large igneous province.The Paleoproterozoic to Mesoproterozoic supercontinent (referred to as Nuna, Hudsonland, or Columbia) formed by assembly of Archean cratons starting at 1.9 Ga and was fully amalgamated as late as 1.65–1.58 Ga (Meert, 2012; Pisarevsky et al., 2014; Pourteau et al., 2018). The position of the Kalahari craton (i.e., here the pre–1.2 Ga conjoined Kaapvaal and Zimbabwe cratons, or the proto-Kalahari craton, sensu stricto; see de Kock et al., 2021) in Columbia is obscured by limited paleomagnetic data. It does not appear in some reconstructions (e.g., Evans and Mitchell, 2011; Pehrsson et al., 2016), but in other reconstructions it is placed at Columbia's periphery (e.g., Zhao et al., 2003) or is regarded as a “lone craton” (Pisarevsky et al., 2014). A craton's position in Columbia is typically evaluated through 1.8–1.3 Ga apparent polar wander path comparison (Evans and Mitchell, 2011). For the Kalahari craton (simply Kalahari hereafter), post–1.8 Ga paleomagnetic data remain sparse (de Kock et al., 2021) and its tenure in Columbia remains unconstrained. Paleomagnetic data from 1.89 to 1.83 Ga magmatic provinces, however, can provide constraints on Kalahari's role in Columbia's assembly.The current 1.89–1.83 Ga paleomagnetic record of Kalahari can be enhanced by studying its magmatic provinces (Fig. 1). The 1.87–1.84 Ga northeast- to north-northeast–trending mafic Black Hills dike swarm (BHDS; South Africa) is one such province (Olsson et al., 2016; Wabo et al., 2019). We present new paleomagnetic data from 36 BHDS dikes together with existing data from the 1.89–1.87 Ga Mashonaland sill province (Söderlund et al., 2010; Hanson et al., 2011) and the 1.88–1.87 Ga post-Waterberg sill province (Hanson et al., 2004). The BHDS is spatially, geochemically, and temporally associated with <1.83 Ga Soutpansberg Basin magmatism (Geng et al., 2014; Olsson et al., 2016) and the ca. 1.8 Ga Mazowe dike swarm of Zimbabwe (Fig. 1B) (Hanson et al., 2011). Paleomagnetic data from the Mashonaland and post-Waterberg sill provinces differ significantly and require large tectonic displacement between the Kaapvaal and Zimbabwe cratons (Hanson et al., 2011). Currently there is no geological support for such displacement. Another explanation may be rapid true polar wander (TPW) (Mitchell et al., 2010; Antonio et al., 2017). Unfortunately, few precisely dated Mashonaland intrusions also have paleomagnetic constraints (Table S3 in the Supplemental Material1). Furthermore, the BHDS was emplaced in the immediate aftermath of the proposed TPW. This limits careful evaluation of the discrepancy. Our data, however, provide a high-resolution paleomagnetic record to test Kalahari's 1.87–1.84 Ga paleogeography.The BHDS is a >300-km-wide swarm of mainly northeast- to north-northeast–trending mafic dikes intruding Archean basement, the 2.68–2.06 Ga Transvaal Supergroup, and the 2.06–2.05 Ga Bushveld and Phalaborwa Complexes (Olsson et al., 2016; Fig. 1). Paleoproterozoic magnetizations that pass reversal and baked-contact tests were reported for the BHDS (Letts et al., 2005, 2011; Lubnina et al., 2010) and are confirmed by combined U-Pb geochronology, geochemistry, and paleomagnetic data sets (Olsson et al., 2016; Wabo et al., 2019). Baddeleyite U-Pb crystallization ages of 12 dikes range between ca. 1.87 and ca. 1.84 Ga (Olsson et al., 2016; Wabo et al., 2019). However, only two dated dikes were also studied paleomagnetically (Lubnina et al., 2010; Wabo et al., 2019). Dike ages do not discriminate between trend or location but subdivide the swarm into an older, 1.88–1.86 Ga, more-primitive group and a younger, 1.85–1.84 Ga, more chemically enriched group (Olsson et al., 2016). The combined BHDS, Mashonaland, and Post-Waterberg sill provinces, and Soutpansberg Basin magmatism (Klausen et al., 2010; Lubnina et al., 2010; Olsson et al., 2016) form an ~50 m.y. record.Baddeleyite grains extracted from an 8–10-m-thick north-northeast–trending dike (dike MAD01 in Fig. 1C) were divided into three fractions and dated by isotope dilution–thermal ionization mass spectrometry (ID-TIMS) at the Department of Geosciences, Swedish Museum of Natural History in Stockholm. The full methodology and data, including geochemistry (Table S2), are provided in the Supplemental Material. Free regression yields upper and lower intercepts at 1850 ± 4 Ma and 200 ± 250 Ma (mean squared weighted deviation [MSWD] = 1.13), respectively (Table S1; Fig. S1). The upper intercept is interpreted as the dike's crystallization age.We sampled 61 dikes for paleomagnetic study using standard methods (see the Supplemental Material; Table S3). Directly dated dikes were explicitly targeted. Each paleomagnetic site sampled a distinct dike and corresponds to a unique cooling unit. High-temperature magnetizations identified in 36 dikes are interpreted as Paleoproterozoic (Fig. 1; Fig. S2). The remaining 25 dikes had heterogeneous demagnetization behavior and are not discussed here (for more detail, see the Supplemental Material). High-temperature remanence components are grouped as northwest (downward) or southeast (upward), showing moderate to steep inclinations. Site means with radii of 95% confidence (α95) >16° were excluded (i.e., 2 of our 36 dikes). The northwest and southeast groups share common precision and are ~180° apart, illustrating a class-C reversal test (Fig. S6). Sampling thus spans one or more reversals of the geomagnetic field. Two dated ca. 1.85 Ga dikes (Olsson et al., 2016), one north trending and one northeast trending (dikes CDL and BJL in Fig. 1C), have positive baked-contact tests supporting the primary Paleoproterozoic nature of the magnetization (see the Supplemental Material). Where directly dated, the crystallization age is assumed also to be the timing of remanence acquisition.Our data (34 dikes) are combined with published BHDS results (29 dikes; Table S3) to define two polarities (Fig. 2A; see the Supplemental Material) and a mean paleopole for the BHDS at 15.3°N, 14.9°E and A95 (radii of 95% confidence) = 5.6° (Table S4; quality, Q, = 7; after Van der Voo, 1990). This pole represents ~30 m.y. and is indistinguishable from the 1.88–1.87 Ga Post-Waterberg sill province and <1.83 Ga Soutpansberg Basin poles (Table S4).Some units from regional magmatic provinces are coeval, and we calculated weighted mean crystallization ages (from U-Pb ID-TIMS baddeleyite dates; Fig. 2B) at 1873 ± 1 Ma (MSWD = 0.62), 1860 ± 2 Ma (MSWD = 0.7), and 1848 ± 2 Ma (MSWD = 0.7). These episodes refine the groupings of Olsson et al. (2016), who named the 1860 Ma episode as “old” and the ca. 1848 Ma episode as “young” BHDS. The crystallization age uncertainty of dike LDH of Wabo et al. (2019) allows it to be a member of either the 1873 Ma or 1860 Ma episode. Dike CDU of this study (sample BCD5-85 of Olsson et al., 2016) can similarly be a member of either the 1860 Ma or 1848 Ma episode. Units of the ca. 1873 Ma episode all have positive inclinations (Fig. 2C). Negatively inclined dike LDH thus likely belongs to the ca. 1860 Ma episode, which is exclusively represented by dikes of negative inclination (Fig. 2C). Besides polarity, the chemical composition provides another discriminator between episodes (Olsson et al., 2016). We note that dikes MAD01 (herein dated at 1850 ± 5 Ma) and LDH (dated at 1867 ± 10 Ma by Wabo et al. [2019]) have MgO contents of 4.9 wt% and 6.0 wt%, respectively (Table S2), which are comparable to those of the “young” and “old” groups, respectively.Only two paleomagnetically constrained units of the Mashonaland sill province are directly dated. One sill has an age corresponding to the ca. 1873 Ma episode, and it has a positive inclination as expected. An older ca. 1883 Ma sill also has positive inclination. The Mashonaland data thus span at least two reversals, and mixed polarity is otherwise assigned to the province (Fig. 2C).Mean poles are calculated for episodes based on dated units. Such poles are temporally better defined than magmatic province poles (Fig. 2D; Table S4). Dated BHDS dikes were exclusively of negative inclination during the ca 1860 Ma and ca. 1848 Ma episodes and of positive inclination during the ca. 1873 Ma episode (Fig. 2C). This defines a late Paleoproterozoic magnetostratigraphic record for Kalahari. All undated BHDS dikes that recorded positive inclinations were used to calculate a ca. 1873 Ma episode pole (11.8°N, 10.6°E and A95 = 11.8°; Table S4; Q = 7). Poles at ca. 1860 Ma and ca. 1848 Ma have larger uncertainties but are statistically indistinguishable from the ca. 1873 Ma pole (Table S4).The timing of Columbia's assembly and its final configuration is debated (Meert, 2012), but there is consensus that Baltica, Laurentia, and Siberia formed the core around which other continents were accreted (e.g., Evans and Mitchell, 2011; Pehrsson et al., 2016), while the suture between Laurentia and Australia occurred as late as 1.6 Ga (Pourteau et al., 2018). At 1.88 Ga, Baltica and Laurentia were not fully assembled. Sarmatia and Volgo-Uralia collided with Fennoscandia (i.e., the Kola craton, Karelia craton, and Svecofennian crust) at 1.82–1.80 Ga to form Baltica. Overlap of 1.89–1.79 Ga Fennoscandian poles suggests that it was fairly stationary (Klein et al., 2016; Fig. 3D). Laurentian assembly occurred between ca. 1.91 Ga and 1.81 Ga (e.g., Mitchell et al., 2014), and its data are discordant. For Superior poles, some discordance is resolved by straightening the Kapuskasing zone (Evans and Halls, 2010). For the Slave and Superior cratons (Figs. 3B and 3C), TPW may account for the remaining dispersion (Mitchell et al., 2010).A comparison of absolute polarity can constrain the relative positions of the Superior, Fennoscandia, and Kalahari cratons. In the late Paleoproterozoic, absolute polarity is assigned to Laurentia based on trade-wind orographic patterns across the Slave craton (Hoffman and Grotzinger, 1993). Driscoll and Evans (2016) followed this rationale and assigned positive inclinations from the Superior craton as normal polarity. In this vane, Fennoscandia showed normal polarity before ca. 1.88 Ga (Fig. 2D). Normal polarity is constrained in Kalahari by a single dated Mashonaland sill. Mixed polarities between 1.89 Ga and 1.87 Ga are otherwise recorded by the Mashonaland sill province (Fig. 2C). Between ca. 1.88 Ga and ca. 1.86 Ga, dual magnetic polarities are described from the ca. 1870 ± 9 Ma Svecofennian Keuruu dikes (paleopole 34 in Table S4; Fig. 2D). The reversal(s) recorded by these dikes can be correlated to either the 1873 Ma or pre–1873 Ma reversals of Kalahari. Normal polarity is reported from the ca. 1863 ± 7 Ma Eastern Murmansk sills of the Kola craton (paleopole 35 in Table S4; Fig. 2D). Given current age constraints, this normal polarity cannot be separated from the ca. 1873 Ma normal polarity chron of Kalahari. The ca. 1840–1837 Ma Haukivesi intrusion (Svecofennia) provides an isolated normal polarity data point for Fennoscandia (paleopole 36 in Table S4; Fig. 2D), but there are no data to compare with Kalahari. On Kalahari, several sites from the <1.83 Ga Soutpansberg Basin yield reverse polarity (Fig. 2C). The shared normal polarity before ca. 1.88 Ga and shared record of a reversal at ca. 1.87 Ga suggest that Fennoscandia and Kalahari were in the same hemisphere, although this should be tested as new data become available.On the Superior craton, the ca. 1.88 Ga Molson dikes record dual polarities as does the ca. 1.87 Ga Haig-Flaherty-Sutton mean (paleopoles 20 and 21 in Table S4; Fig. 2D). Reversals represented by these data may correlate to the post–1873 Ma Kalahari reversal. It is, however, important to note potential disagreement with this model in terms of 1850–1830 Ma normal polarities recorded by the ca. 1850 Ma but poorly dated Sudbury irruptive and the ca. 1838 Ma Boot-Phantom pluton (Hood, 1961; Symons and McKay, 1999). Both these results were, however, excluded from quality-filtered Laurentian data (Swanson-Hysell, 2021).At 1.88 Ga, Kalahari restores to 45°–59° paleolatitude, Fennoscandia to 11°–28°, and the Superior craton to 32°–58° (Fig. 3E). The Superior-Nain block can be placed in a position northeast of Fennoscandia preceding the Northern Europe–North America (NENA) configuration (Klein et al., 2016) by overlapping the 1.88 Ga Molson dikes pole with 1.89–1.84 Ga Fennoscandian poles (Figs. 3B and 3D). The 1.89–1.83 Ga Kalahari poles are overlapped with the 1.88 Ga Molson dikes pole. Kalahari is placed to the west of the reconstructed Superior craton adjacent to the Penokean orogen (Fig. 3E). The modern southwestern margin of the Superior craton is occupied by the 1.77–1.60 Ga Central Plains, Yavapai, and Mazatzal orogens (Whitmeyer and Karlstrom, 2007). Placing Kalahari to the east of the Superior craton is permissible in paleolatitude, but the area is occupied by the Manikewan Ocean (Fig. 3E). Restoration of Kalahari to the west of the Superior craton, in contrast to “lone-craton” configurations, aligns the BHDS and the Mazowe dike swarm into a radiating pattern around the ca. 1.88 Ga Circum-Superior large igneous province magmatic center (Minifie et al., 2013). This event thus likely included the intraplate magmatism of Kalahari as well as that of Fennoscandia (Fig. 4). In this position, overlap is also achieved between the ca. 2.0 Ga Kalahari and Superior craton poles (Fig. 3E). This suggests a longer-lived link, and it is interesting to note that the Kaapvaal craton at ca. 2.43 Ga was similarly reconstructed (Gumsley et al., 2017). If this is correct, it implies that a loop in apparent polar wander (defined by paleopoles 6 and 7 in Table S4; Fig. 3A) has gone unrecognized in the Superior craton. Furthermore, in our model, there is alignment between the Kapuskasing zone of the Superior craton and the Thabazimbi-Murchison lineament of Kalahari, as well as possible continuation between the Limpopo and Penokean orogens (Fig. 4). On the opposite side of the Manikewan Ocean, the Slave-Rae craton is reconstructed at low paleolatitude using the ca. 1.88 Ga Ghost dike swarm and mean Kahochella–Peacock Hills poles (paleopoles 23 and 25 in Table S4; Fig. 3C). The Ghost dike swarm pole is considered more reliable than similarly aged poles from the Slave craton (Swanson-Hysell, 2021).After ca. 1.88 Ga, Kalahari and Fennoscandia remained fairly fixed as formation of the Russian belt concluded the assembly of Baltica. At the same time, the Superior craton is envisaged to have rotated clockwise into a classic NENA configuration, leading to possible extension between it and Kalahari and the ultimate closure of the Manikewan Ocean. Unfortunately, a 1.83–1.40 Ga lacuna in Kalahari's paleomagnetic data prevent evaluation of its position throughout the existence of Columbia, but our 1.88 Ga reconstruction does suggest a peripheral position for the craton early during Columbia's assembly.We thank D.A.D. Evans, R.N. Mitchell, and an anonymous reviewer. C. Djeutchou, M. de Kock and H. Wabo acknowledge support of the South African Department of Science and Innovation–National Research Foundation Centre of Excellence for Integrated Mineral and Energy Resource Analysis (DSI-NRF CIMERA) and a National Research Foundation development grant (RDYR14080787934). A. Gumsley acknowledges support through a Polish National Science Centre grant (POLONEZ grant UMO-2016/23/P/ST10/02423), funded from the European Union's Horizon 2020 research and innovation program under the Marie Skłodowska-Curie Actions CO-FUND-2014 (grant 665778). A. Gumsley also acknowledges the support of the EPOS-PL project (No. POIR.04.02.00-14-A003/16), co-financed by the European Union from funds of the European Regional Development Fund (ERDF) to the laboratory facilities at IG PAS used in the study.

中文翻译：

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晚古元古代基性岩浆作用和哥伦比亚组装期间的喀拉哈里克拉通

喀拉哈里克拉通（南非）的 1.87–1.84 Ga Black Hills 堤坝群与几个区域性岩浆省份同时代，这里用于确定哥伦比亚组装期间克拉通的位置。我们报告了一个新的 1850 ± 4 Ma（斜锆石上的 U-Pb 同位素稀释-热电离质谱 [ID-TIMS]）结晶年龄和 34 个岩脉的新古地磁数据，其中 8 个具有精确的 U-Pb 年龄。结果受到正烘焙接触和反转测试的限制，结合现有数据从 63 个单独的堤防中产生 1.87–1.84 Ga 平均极点。通过整合古地磁和地质年代数据集，我们计算了三个岩浆事件的极点并产生了磁地层记录。在 1.88 Ga，喀拉哈里克拉通在上级克拉通旁边重建，因此它们的约。2.0 Ga 极对齐。因此，岩浆活动与同时代的约形成辐射模式的一部分。1.88 Ga Circum-Superior 大型火成岩省。古元古代至中元古代超大陆（称为 Nuna、Hudsonland 或 Columbia）由从 1.9 Ga 开始的太古代克拉通集合形成，并在 1.65-1.52 Ga（Meert，Meert，Meert，Meert， ；Pisarevsky 等人，2014 年；Pourteau 等人，2018 年）。哥伦比亚的喀拉哈里克拉通（即这里是 1.2 Ga 之前的 Kaapvaal 和津巴布韦克拉通，或原始喀拉哈里克拉通，严格意义上的；参见 de Kock 等，2021）的位置被有限的古地磁数据所掩盖。它没有出现在一些重建中（例如，Evans 和 Mitchell，2011；Pehrsson 等，2016），但在其他重建中它被放置在哥伦比亚的外围（例如，Zhao 等，2003）或被视为“孤立的克拉通”（Pisarevsky 等，2014）。克拉通在哥伦比亚的位置通常是通过 1.8-1.3 Ga 表观极地漂移路径比较来评估的（Evans 和 Mitchell，2011）。对于 Kalahari 克拉通（以下简称 Kalahari），1.8 Ga 后的古地磁数据仍然稀少（de Kock 等，2021），其在哥伦比亚的使用期限仍然不受限制。然而，从 1.89 到 1.83 Ga 岩浆区的古地磁数据可以限制喀拉哈里在哥伦比亚组装中的作用。通过研究其岩浆区可以增强喀拉哈里目前 1.89 到 1.83 Ga 的古地磁记录（图 1）。1.87-1.84 Ga 东北-东北-东北-趋向的基性黑山堤防群（BHDS；南非）就是这样的一个省（Olsson 等人，2016 年；Wabo 等人，2019 年）。我们提供了来自 36 个 BHDS 堤坝的新古地磁数据以及来自 1.89-1.87 Ga Mashonaland 基台省（Söderlund 等人，2010；Hanson 等人，2011）和 1.88-1.87 Ga 后沃特伯格基台省（Hanson）的现有数据等人，2004 年）。BHDS 在空间、地球化学和时间上与 <1.83 Ga Soutpansberg 盆地岩浆活动有关（Geng 等人，2014 年；Olsson 等人，2016 年）和约。1.8 津巴布韦 Ga Mazowe 堤防群（图 1B）（Hanson 等，2011）。来自马绍纳兰和后沃特伯格基石省的古地磁数据存在显着差异，需要在 Kaapvaal 和津巴布韦克拉通之间进行大的构造位移（Hanson 等，2011）。目前没有这种位移的地质支持。另一种解释可能是快速真极地漂移 (TPW)（Mitchell 等人，2010 年；Antonio 等人，2017 年）。不幸的是，很少有精确日期的 Mashonaland 侵入体也有古地磁限制（补充材料中的表 S3）。此外，在提议的 TPW 之后立即部署了 BHDS。这限制了对差异的仔细评估。然而，我们的数据提供了高分辨率古地磁记录来测试卡拉哈里的 1.87-1.84 Ga 古地理。 BHDS 是一个 > 300 公里宽的群，主要是东北向北-东北-趋向的基性岩脉侵入太古代基底，即 2.68 –2.06 Ga 德兰士瓦超群，以及 2.06–2.05 Ga Bushveld 和 Phalaborwa 复合体（Olsson 等，2016；图 1）。BHDS 报告了通过反转和烘烤接触测试的古元古代磁化强度（Letts 等人，2005 年，2011 年；Lubnina 等人，2010 年），并通过 U-Pb 年代学、地球化学、和古地磁数据集（Olsson 等人，2016 年；Wabo 等人，2019 年）。12 个岩脉的斜锆石 U-Pb 结晶年龄介于约 1.87 和大约 1.84 Ga（Olsson 等人，2016 年；Wabo 等人，2019 年）。然而，只有两个年代久远的堤防也进行了古地磁研究（Lubnina 等人，2010 年；Wabo 等人，2019 年）。堤防年龄不区分趋势或位置，而是将群体细分为年龄较大的 1.88-1.86 Ga，更原始的组和更年轻的 1.85-1.84 Ga，化学物质更丰富的组（Olsson 等，2016）。BHDS、Mashonaland 和 Post-Waterberg 基石省，以及 Soutpansberg 盆地岩浆作用（Klausen 等人，2010 年；Lubnina 等人，2010 年；Olsson 等人，2016 年）形成了大约 50 个我的记录。从一个 8-10 米厚的北-东北-趋向堤坝（图 1 中的堤防 MAD01）。1C) 被分成三个部分，并在斯德哥尔摩瑞典自然历史博物馆地球科学系通过同位素稀释-热电离质谱 (ID-TIMS) 测定日期。补充材料中提供了完整的方法和数据，包括地球化学（表 S2）。自由回归分别在 1850 ± 4 Ma 和 200 ± 250 Ma（均方加权偏差 [MSWD] = 1.13）处产生上截距和下截距（表 S1；图 S1）。上截距被解释为岩脉的结晶年龄。我们使用标准方法对 61 个岩脉进行了古地磁研究（见补充材料；表 S3）。直接注明日期的堤防是明确的目标。每个古地磁站点都对一个不同的堤坝进行采样，并对应于一个独特的冷却单元。在 36 个岩脉中确定的高温磁化被解释为古元古代（图 1；图 S2）。其余 25 个堤防具有异质退磁行为，此处未讨论（有关更多详细信息，请参阅补充材料）。高温剩磁成分分为西北（向下）或东南（向上），显示出中等至陡峭的倾斜度。排除了半径为 95% 置信度 (α95) > 16° 的站点平均值（即我们 36 个堤防中的 2 个）。西北组和东南组具有相同的精度并且相距约 180°，说明了 C 级反转测试（图 S6）。因此，采样跨越地磁场的一次或多次反转。两个日期约。1.85 Ga 堤坝 (Olsson et al., 2016)，一条北向和一条东北向（图 1C 中的堤坝 CDL 和 BJL），具有正面的烘烤接触测试，支持磁化的主要古元古代性质（参见补充材料）。在直接注明日期的情况下，结晶年龄也被假定为剩磁采集的时间。我们的数据（34 个岩脉）与已公布的 BHDS 结果（29 个岩脉；表 S3）相结合，以定义两种极性（图 2A；参见补充材料） ) 和 BHDS 在 15.3°N、14.9°E 和 A95（95% 置信度的半径）= 5.6° 处的平均古极地（表 S4；质量，Q，= 7；在 Van der Voo 之后，1990 年）。这个极点代表 ~30 my 并且与 1.88-1.87 Ga Post-Waterberg 基台省和 <1.83 Ga Soutpansberg Basin 盆地极点没有区别（表 S4）。来自区域岩浆省的一些单元是同时期的，我们计算了加权平均结晶年龄（从U-Pb ID-TIMS斜锆石日期；图。2B) 在 1873 ± 1 Ma (MSWD = 0.62)、1860 ± 2 Ma (MSWD = 0.7) 和 1848 ± 2 Ma (MSWD = 0.7)。这些情节完善了 Olsson 等人的分组。（2016 年），他将 1860 年的 Ma 剧集命名为“旧的”，而约 1848 Ma 插曲作为“年轻的”BHDS。Wabo等人的堤防LDH结晶年龄不确定性。(2019) 允许它成为 1873 Ma 或 1860 Ma 剧集的成员。本研究的 Dike CDU（Olsson 等人的样本 BCD5-85，2016 年）同样可以是 1860 Ma 或 1848 Ma 事件的成员。大约的单位。1873 Ma 情节都有积极的倾向（图 2C）。因此，负倾斜的堤防 LDH 可能属于约。1860 Ma 事件，完全由负倾角的堤坝代表（图 2C）。除了极性之外，化学成分还提供了剧集之间的另一个鉴别器（Olsson 等人，2016 年）。我们注意到堤防 MAD01（本文中的日期为 1850 ± 5 Ma）和 LDH（Wabo 等人的日期为 1867 ± 10 Ma，[2019]）分别具有 4.9 wt% 和 6.0 wt% 的 MgO 含量（表 S2），分别与“年轻”和“老”组的那些相媲美。只有马绍纳兰基尔省的两个古地磁约束单元被直接定年。一个基石的年龄对应于大约。1873 Ma 情节，它具有预期的积极倾向。一个较旧的约。1883 Ma sill 也有正倾向。因此，Mashonaland 数据跨越至少两次逆转，并且混合极性以其他方式分配给该省（图 2C）。平均极点是基于日期单位计算的情节。这样的极点在时间上比岩浆省的极点定义得更好（图 2D；表 S4）。在约 1860 Ma 和约 1860 年期间，日期 BHDS 堤坝完全呈负倾角。1848 年 Ma 事件和大约在 1848 年期间的积极倾向。1873 Ma 插曲（图 2C）。这定义了喀拉哈里的晚古元古代磁地层记录。记录正倾角的所有未注明日期的 BHDS 堤防都用于计算约。1873 Ma 极点（11.8°N，10.6°E 和 A95 = 11.8°；表 S4；Q = 7）。波兰人在ca。约 1860 年 1848 Ma 具有更大的不确定性，但在统计上与 ca 没有区别。1873 Ma 极（表 S4）。哥伦比亚的组装时间及其最终配置存在争议（Meert，2012），但人们一致认为波罗的海、劳伦特和西伯利亚形成了其他大陆围绕其增生的核心（例如，埃文斯和西伯利亚）。米切尔，2011 年；佩尔森等人，2016 年），而 Laurentia 和澳大利亚之间的缝合最晚发生在 1.6 Ga（Pourteau 等人，2018 年）。在 1.88 Ga，Baltica 和 Laurentia 尚未完全组装。Sarmatia 和 Volgo-Uralia 与 Fennoscandia（即科拉克拉通、卡累利阿克拉通和 Svecofennian 地壳）在 1.82-1.80 Ga 碰撞形成波罗的海。1.89-1.79 Ga Fennoscandian 极点的重叠表明它相当稳定（Klein 等人，2016 年；图 3D）。劳伦装配发生在大约之间。1.91 Ga 和 1.81 Ga（例如，Mitchell 等人，2014），其数据不一致。对于上极点，通过拉直 Kapuskasing 区域可以解决一些不一致问题（Evans 和 Halls，2010 年）。对于 Slave 和 Superior 克拉通（图 3B 和 3C），TPW 可能解释了剩余的弥散（Mitchell 等，2010）。绝对极性的比较可以限制上级、芬诺斯坎迪亚和喀拉哈里克拉通的相对位置。在古元古代晚期，根据横跨奴隶克拉通的信风地形模式，绝对极性被赋予劳伦大陆（Hoffman 和 Grotzinger，1993）。Driscoll 和 Evans (2016) 遵循这一基本原理并将上克拉通的正倾角指定为正常极性。在这个风向标中，Fennoscandia 在大约 10 年前显示出正常的极性。1.88 Ga（图 2D）。正常极性在喀拉哈里受到单一年代的 Mashonaland 地台的限制。1.89 Ga 和 1.87 Ga 之间的混合极性由马绍纳兰基尔省记录（图 2C）。之间约。1.88 Ga 和约 1.86 Ga，从大约描述了双磁极性。1870 ± 9 Ma Svecofennian Keuruu 堤防（表 S4 中的古极 34；图 2D）。这些堤坝记录的逆转可能与 1873 年 Ma 或 1873 年之前的卡拉哈里逆转相关。从大约报告正常极性。1863 ± 7 Ma 科拉克拉通的东摩尔曼斯克基岩（表 S4 中的古极地 35；图 2D）。鉴于当前的年龄限制，这种正常的极性无法与大约分开。1873 Ma 卡拉哈里正常极性纪年。约。1840-1837 年 Ma Haukivesi 入侵（Svecofennia）为 Fennoscandia（表 S4 中的古极 36；图 2D）提供了一个孤立的正常极性数据点，但没有数据可与 Kalahari 进行比较。在 Kalahari，来自 <1.83 Ga Soutpansberg 盆地的几个站点产生反向极性（图 2C）。之前共享的正常极性。1.88 Ga 和在约 1.88 Ga 逆转的共享记录。1.87 Ga 表明芬诺斯坎迪亚和喀拉哈里在同一个半球，尽管这应该在新数据可用时进行测试。1.88 Ga Molson 堤坝和约 1.88 Ga Molson 堤坝记录了双重极性。1.87 Ga Haig-Flaherty-Sutton 平均值（表 S4 中的古极地 20 和 21；图 2D）。这些数据所代表的逆转可能与 1873 年后的 Ma Kalahari 逆转有关。然而，重要的是要注意与该模型在约 1850-1830 Ma 正常极性方面的潜在分歧。1850 Ma 但年代不长的萨德伯里破坏性和约。1838 Ma Boot-Phantom 岩体（Hood，1961；Symons 和 McKay，1999）。然而，这两个结果都被排除在质量过滤的 Laurentian 数据之外（Swanson-Hysell，2021 年）。在 1.88 Ga，Kalahari 恢复到 45°–59° 古纬度，Fennoscandia 恢复到 11°–28°，而上级克拉通恢复到 32 °–58°（图 3E）。通过将 1.88 Ga Molson 堤防极与 1.89-1.84 Ga Fennoscandian 极点重叠，Superior-Nain 地块可以放置在北欧-北美 (NENA) 配置（Klein 等人，2016 年）之前的 Fennoscandia 东北位置（图和图） .3B 和 3D）。1.89–1.83 Ga Kalahari 极点与 1.88 Ga Molson 堤防极点重叠。Kalahari 位于重建的上克拉通西部，毗邻 Penokean 造山带（图 3E）。苏必利尔克拉通现代西南边缘被 1.77-1.60 Ga 中央平原、Yavapai 和 Mazatzal 造山带所占据（Whitmeyer 和 Karlstrom，2007）。将卡拉哈里置于上克拉通以东在古纬度上是允许的，但该地区被马尼克湾洋占据（图 3E）。卡拉哈里恢复到苏必利尔克拉通以西，与“孤立克拉通”配置相反，将 BHDS 和 Mazowe 堤坝群排列成围绕约的辐射模式。1.88 Ga Circum-Superior 大型火成岩省岩浆中心(Minifie et al., 2013)。因此，该事件可能包括喀拉哈里和芬诺斯坎迪亚的板内岩浆活动（图 4）。在这个位置，ca 之间也实现了重叠。2.0 Ga Kalahari 和 Superior 克拉通极（图 3E）。这表明存在更长时间的联系，有趣的是注意到大约在 10 年前的 Kaapvaal 克拉通。2.43 Ga 也进行了类似的重建（Gumsley 等，2017）。如果这是正确的，则意味着明显的极地漂移环（由表 S4 中的古极地 6 和 7 定义；图 3A）在上克拉通中未被识别。此外，在我们的模型中，上级克拉通的 Kapuskasing 带与 Kalahari 的 Thabazimbi-Murchison 构造线之间存在对齐，以及 Limpopo 和 Penokean 造山带之间可能的延续（图 4）。在马尼克湾洋的另一边，Slave-Rae 克拉通是在低古纬度使用 ca. 重建的。1.88 Ga 鬼堤群和平均 Kahochella-孔雀山两极（表 S4 中的古极地 23 和 25；图 3C）。幽灵堤防群杆被认为比奴隶克拉通的类似年龄的杆更可靠（Swanson-Hysell，2021 年）。1.88 Ga、Kalahari 和 Fennoscandia 仍然相当固定，因为俄罗斯带的形成结束了波罗的海的组装。与此同时，Superior craton 被设想顺时针旋转成经典的 NENA 配置，导致它和喀拉哈里之间可能的延伸以及马尼克湾海洋的最终关闭。不幸的是，卡拉哈里古地磁数据中的 1.83-1.40 Ga 空隙阻止了对它在哥伦比亚整个存在期间的位置进行评估，但我们的 1.88 Ga 重建确实表明在哥伦比亚组装期间早期克拉通的外围位置。我们感谢 DAD Evans、RN Mitchell 和匿名审稿人。C. Djeutchou、M. de Kock 和 H. Wabo 承认南非科学与创新部 - 国家研究基金会综合矿产和能源资源分析卓越中心 (DSI-NRF CIMERA) 和国家研究基金会发展赠款的支持(RDYR14080787934)。A. Gumsley 通过波兰国家科学中心拨款（POLONEZ 拨款 UMO-2016/23/P/ST10/02423）承认支持，由 Marie Skłodowska-Curie Actions CO-FUND-2014（拨款 665778）下的欧盟地平线 2020 研究和创新计划资助。A. Gumsley 也感谢 EPOS-PL 项目 (No. POIR.04.02.00-14-A003/16) 的支持，该项目由欧盟共同资助，由欧洲区域发展基金 (ERDF) 的基金提供给实验室研究中使用的 IG PAS 设施。