Abstract The Sierra de Juárez Complex (SJC) of southern Mexico contains an extensive geological record from Precambrian to Cenozoic, involving Rodinia, NW Gondwana, western equatorial Pangaea, and eastern peninsular Mexico. It is thus critical for palinspastic reconstructions and lithotectonic correlations, mainly between the Mexican and NW South America terranes. In this contribution, we investigate the tectonic evolution of the northern SJC from Silurian to the Lower Cretaceous on the basis of fieldwork, petrography, and zircon U–Pb geochronology by laser ablation–inductively coupled plasma mass spectrometry. Our results allow us to constrain five main geological events: (1) Middle Paleozoic sedimentation along NW Gondwana during transtensional tectonics; (2) volcanosedimentary activity between 292 and 281 Ma in NW Gondwana during Rheic Ocean closure; (3) early-middle Permian metamorphism related to flat-slab subduction postdating Pangaea assembly; (4) Lower–Middle Jurassic anatexis and magmatism coeval with regional shearing at c. 175 Ma influenced by transtensional tectonics along eastern peninsular Mexico during Pangaea tenure; and (5) intermediate to acid magmatism between c. 136 and 129 Ma, correlated with the Zongolica continental arc in southern Mexico, followed by deep-crustal shearing related to either the formation of the extensional Chivillas basin or the Upper Cretaceous–Cenozoic contractional episode documented in the Cuicateco Terrane.

Abstract The eruption of the c. 10 km 3 rhyolitic Las Derrumbadas twin domes about 2000 years ago generated a wide range of volcano-sedimentary deposits in the Serdán-Oriental lacustrine basin, Trans-Mexican Volcanic Belt. Some of these deposits have been quarried, creating excellent exposures. In this paper we describe the domes and related products and interpret their mode of formation, reconstructing the main phases of the eruption as well as syn- and post-eruptive erosional processes. After an initial phreatomagmatic phase that built a tuff ring, the domes grew as an upheaved plug, lifting a thick sedimentary pile from the basin floor. During uplift, the domes collapsed repeatedly to form a first generation of hetero-lithologic hummocky debris avalanche deposits. Subsequent dome growth produced a thick talus and pyroclastic density currents. Later, the hydrothermally altered over-steepened dome peaks fell to generate second-generation, mono-lithologic avalanches. Subsequently, small domes grew in the collapse scars. From the end of the main eruptive episode onwards, heavy rains remobilized parts of the dome carapaces and talus, depositing lahar aprons. The Las Derrumbadas domes are still an important source of sediments in the basin, and ongoing mass-wasting processes are associated with hazards that should be assessed, given their potential impact on nearby populations.

Abstract Volcán de Colima, one of the most active volcanoes in Mexico, experienced at least nine flank failures during the last 30 000 years, with catastrophic effects on the environment that implies the formation of temporary dams where lacustrine sediments accumulated for hundreds of years. These lacustrine sequences preserve an exceptional record from which to reconstruct the effect of subsequent volcanic eruptions and, eventually, contemporary environmental and climatic conditions. Here we analyse an Early Holocene lacustrine sequence, named ‘Gypsum King’, which accumulated in a short-lived temporary lake, likely formed by emplacement of the 10 755–11 230 cal years BP Mesa-Yerbabuena debris avalanche. Through detailed analysis of the 1.8 m thick lacustrine sequence ( 14 C ages, sulfur content, grain size), it was possible to identify the 8.2 kyr global climate event and better constrain the Early Holocene main sub-plinian to plinian eruptions of Volcán de Colima. The results presented here highlight the potential to explore sulfur content and abrupt change in grain size in lacustrine sediments as additional proxies to better constrain eruptive phases in volcanic environments. Finally, the Gypsum King sequence provides the first evidence of the 8.2 kyr global climate event along the Eastern tropical Pacific Coast.