The present work gives a detailed analysis of the metamorphic and deformational evolution of the back-arc portion of the Famatinian Orogen exposed in the southern Sierra de Aconquija (Cuesta de La Chilca segment) in the Eastern Pampean Sierras. The Eastern Pampean Sierras include from north to south the Aconquija, Ambato and Ancasti mountains. They are mainly composed of middle to high grade metasedimentary units and magmatic rocks.

At the south end of the Sierra de Aconquija, along an east to west segment extending over nearly 10 km long (Cuesta de La Chilca), large volumes of metasedimentary rocks crop out. The eastern metasediments were defined as members of the El Portezuelo Metamorphic–Igneous Complex (EPMIC) or Eastern block and the western ones relate to the Quebrada del Molle Metamorphic Complex (QMMC) or Western block. The two blocks are divided by the La Chilca Shear Zone, which is reactivated as the Río Chañarito fault.

The EPMIC, forming the hanging wall, is composed of schists, gneisses and rare amphibolites, calc– silicate schists, marbles and migmatites. The rocks underwent multiple episodes of deformation and a late high strain-rate episode with gradually increasing mylonitization to the west. Metamorphism progrades from an M₁ phase to the peak M₃, characterized by the reactions: Qtz + Pl + Bt ± Ms → Grt + Bt₂ + Pl₂ ± Sil ± Kfs, Qtz + Bt + Sil → Crd + Kfs and Qtz + Grt + Sil→ Crd. The M₃ assemblage is coeval with the dominant foliation related to a third deformational phase (D₃).

The QMMC, forming the foot wall, is made up of fine-grained banded quartz – biotite schists with quartz veins and quartz-feldspar rich pegmatites. To the east, schists are also overprinted by mylonitization. The M₃ peak assemblage is quartz + biotite + plagioclase ± garnet ± sillimanite ± muscovite ± ilmenite ± magnetite ± apatite.

The studied segment suffered multiphase deformation and metamorphism. Some of these phases can be correlated between both blocks. D₁ is locally preserved in scarce outcrops in the EPMIC but is the dominant in the QMMC, where S₁ is nearly parallel to S₀. In the EPMIC, D₂ is represented by the S₂ foliation, related to the F₂ folded that overprints S₁, with dominant strike NNW – SSE and high angles dip to the E. D₃ in the EPMIC have F₃ folds with axis oblique to S₂; the S₃ foliation has striking NW – SE dipping steeply to the E or W and develops interference patterns. In the QMMC, S₂ (D₂) is a discontinuous cleavage oblique to S₁ and transposed by S₃ (D₃), subparallel to S₁. Such structures in the QMMC developed at subsolidus conditions and could be correlated to those of the EPMIC, which formed under higher P-T conditions. The penetrative deformation D₂ in the EPMIC occurred during a prograde path with syntectonic growth of garnet reaching P-T conditions of 640 °C and 0.54 GPa in the EPMIC. This stage was followed by a penetrative deformation D₃ with syn-kinematic growth of garnet, cordierite and plagioclase. Peak P-T conditions calculated for M₃ are 710 °C and 0.60 GPa, preserved in the western part of the EPMIC, west of the unnamed fault.

The schists from the QMMC suffered the early low grade M₁ metamorphism with minimum PT conditions of ca 400 °C and 0.35 GPa, comparable to the fine schists (M₁) outcropping to the east. The D₂ deformation is associated with the prograde M₂ metamorphism. The penetrative D₃ stage is related to a medium grade metamorphism M₃, with peak conditions at ca 590 °C and 0.55 GPa.

The superimposed stages of deformation and metamorphism reaching high P-T conditions followed by isothermal decompression, defining a clockwise orogenic P-T path. During the Lower Paleozoic, it was generating superimposed folding and recrystallization, with partial melting at peak conditions. Similar characteristics were described from the basement from other Famatinian-dominated locations of the Sierra de Aconquija and other ranges of the Eastern Pampean Sierras.

本工作详细分析了东部潘皮斯山脉塞拉利昂山脉南部（Cuesta de La Chilca段）暴露的法马汀造山带后弧部分的变质和变形演化。东部的潘邦山脉包括从北到南的阿孔基亚山脉，安巴托山脉和安卡斯蒂山脉。它们主要由中高品位的沉积沉积单元和岩浆岩组成。

在塞拉利昂德阿孔基亚山脉（Serra de Aconquija）的南端，沿着东西向延伸超过10公里（库埃斯塔·德拉奇尔卡（Cuesta de La Chilca））的东段，大量的沉积岩形成了。东部的沉积物被定义为El Portezuelo变质—火成复合体（EPMIC）或东部地块的成员，而西部的则与Quebrada del Molle变质复合体（QMMC）或Western地块有关。这两个区块被拉奇尔卡剪切带划分，该区域被重新激活为里奥·查尼亚里托断层。

的EPMIC，形成挂壁，由片岩，片麻岩和稀有闪岩，calc-硅酸盐片岩，大理石和混合岩的。岩石经历了多次变形和后期的高应变率事件，并逐渐向西扩展了髓鞘化作用。变质从M ₁相推进到峰M ₃，其特征在于以下反应：Qtz + Pl + Bt±Ms→Grt + Bt ₂  + Pl ₂  ±Sil±Kfs，Qtz + Bt + Sil→Crd + Kfs和Qtz + Grt + Sil→Crd。M ₃组合与与第三变形相（D ₃）有关的主要叶面同时存在。

形成底壁的QMMC由细颗粒的带状石英–黑云母片岩和石英脉和富含石英长石的伟晶岩组成。在东部，片岩也被殖民化所覆盖。M ₃峰组合为石英+黑云母+斜长石±石榴石±硅线石±白云母±钛铁矿±磁铁矿±磷灰石。

所研究的段经历了多相变形和变质作用。这些阶段中的某些阶段可以在两个模块之间建立关联。D ₁在EPMIC中的稀有露头中局部保留，但在QMMC中占主导地位，其中S ₁几乎与S ₀平行。在EPMIC，d ₂是由S表示的₂叶理，关于F ₂折叠该叠印小号₁，与主导击NNW - SSE和高角度倾角到E. d ₃在EPMIC了F- ₃倍与轴倾斜于S ₂ ; S ₃西北-东南向陡峭地倾斜到E或W，并形成干涉图样。在QMMC中，S ₂（D ₂）是倾斜于S ₁并由S ₃（D ₃）换位，不平行于S ₁的不连续卵裂。QMMC中的此类结构在亚固相线条件下发展，并且可能与在较高PT条件下形成的EPMIC的结构相关。EPMIC中的渗透变形D ₂发生在前进阶段，石榴石的共晶生长达到PT温度为640°C和0.54 GPa的PT条件。该阶段之后是渗透变形D _3。与石榴石，堇青石和斜长石的运动学相关。计算出的M _3的PT峰值条件为710°C和0.60 GPa，保存在EPMIC的西部，未命名断层的西部。

来自QMMC的片岩经历了早期的低等级M ₁变质作用，其最低PT条件约为400°C和0.35 GPa，与东部露出的细片岩片（M ₁）相当。D ₂变形与前进的M ₂变质有关。渗透性D ₃阶段与中等等级的变质M _3有关，其峰值条件约为590°C和0.55 GPa。

变形和变质的叠加阶段达到高PT条件，然后进行等温减压，定义了顺时针造山PT路径。在下古生代，它产生叠加的褶皱和重结晶，在峰值条件下部分熔融。从地下室中发现了类似的特征，这些地下室由法马汀人统治的塞拉利昂德阿孔基亚山脉（Serra de Aconquija）的其他地方以及东邦庞该山脉的其他范围。