Abstract The Central Patagonian Batholith (CPB) in the Gastre area, central Patagonia, constitutes a set of two I-type Late Triassic plutonic suites, the Gastre superunit with a U-Pb zircon age of 221 ± 2 Ma, and the Lipetren superunit with a U-Pb SHRIMP age of 215 ± 1 Ma. The source of this calc-alkaline batholith is characterized by crustal and mantle contributions, and it registers NW-SE subvertical magmatic and solid-state fabrics. These features, together with its intraplate position away from the inferred proto-Gondwana margin, have made it the focus of different tectonic interpretations. Early studies have interpreted it as the record of major dextral motions along the transcontinental NW-SE-striking Gastre fault system in Jurassic times. Later interpretations have proposed that the magmatic and tectonic foliations of the CPB were formed during a sinistral transpressive regime which was aided by Late Paleozoic widespread NW-SE subvertical structures in the North Patagonian Massif. Paleomagnetism, a unique tool to detect the presence of tectonic block rotations on vertical axes, was applied in the CPB in order to constrain the timing and type of deformation in the area. A paleomagnetic pole was obtained, which statistical parameters are: N = 45, Lat. = 81.4°S, Long. = 207°E, K = 11.5, A95 = 6.6°. Although the position of this pole does not coincide with equivalent Late Triassic poles, this position can be reconciled with the presence of a NE tilting of about 11° of the sampled block of the batholith. The tilting would have been aided by the NW-SE subvertical structures that affect the area. These paleomagnetic results rule out the possibility of vertical axis rotations from Late Triassic to present times and suggest that the ductile syn- to post-emplacement deformation of the CPB in Gastre area occurred during this period (Late Triassic), being the later brittle deformation triggered by the Andean Orogeny a possible explanation for this tilting.

中文翻译：

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加斯特地区（阿根廷丘布特省）巴塔哥尼亚中部基岩脆性变形的古地磁证据

摘要 巴塔哥尼亚中部Gastre地区的中央巴塔哥尼亚基岩（CPB）由2个I型晚三叠世深成岩套组成，Gastre超单元的U-Pb锆石年龄为221±2 Ma，Lipetren超单元的U-Pb锆石年龄为221±2 Ma。 U-Pb SHRIMP 年龄为 215 ± 1 Ma。这种钙碱性基岩的来源以地壳和地幔的贡献为特征，它记录了 NW-SE 亚垂直岩浆和固态结构。这些特征，连同其远离推断的原始冈瓦纳大陆边缘的板内位置，使其成为不同构造解释的焦点。早期的研究将其解释为侏罗纪时期沿横贯大陆的 NW-SE 走向的 Gastre 断层系统的主要右旋运动的记录。后来的解释提出，CPB 的岩浆和构造叶理形成于左旋压压体制期间，该体制得到了北巴塔哥尼亚地块晚古生代广泛的 NW-SE 近垂直结构的帮助。古地磁是一种检测垂直轴上构造块旋转存在的独特工具，被应用于 CPB 以限制该地区变形的时间和类型。得到了一个古地磁极，其统计参数为：N = 45，Lat。= 81.4°S，长。= 207°E，K = 11.5，A95 = 6.6°。尽管该极点的位置与等效的晚三叠世极点不一致，但该位置可以与基岩采样块的 NE 倾斜约 11° 的存在相协调。影响该地区的 NW-SE 亚垂直结构有助于倾斜。这些古地磁结果排除了晚三叠世至今垂直轴旋转的可能性，表明Gastre地区CPB的韧性同向至侵位后变形发生在这一时期（晚三叠世），是晚三叠世触发的脆性变形。安第斯造山运动对这种倾斜的可能解释。