Abstract The first part of the trip travels northwest from San Luis Potosi to Zacatecas. An extensive collection of Tertiary volcanic rocks covers the base sediments west of San Luis Potosi. Rocks are mainly rhyolite tuffs, latites, and layered volcanic limolites. Another important volcanic center is the Los Pinos, which is a complex formed by clastic rocks, red beds, trachytes, and rhyolite tuffs. Historically, mining in the area has been active and was first reported in epithermal Au-Ag vein mineralization related to the mid-Tertiary sequence formed by domes, associated lava flows, and ash-flow tuffs. Peñon Blanco (San José) is an emergent mining district that has been explored recently. Rocks reported in the area include the basement, formed by Cuesta del Cura limestone and rocks of the Chilitos Formation. This sequence of rocks is intruded by the Peñon Blanco batholith, which has created a halo of marble rock in the contact with the sedimentary and volcanosedimentary rocks. Mineralization occurs in quartz veins and skarn, and main ores are silver, lead, zinc, and little copper. The city of Zacatecas is situated within a horst formed by NE-trending normal faults. The Mesozoic Chilitos Formation, siltstones, phyllites, and rhyolites are the main host rocks for mineralization in the region. Two of the major producer mines are located nearby: The Francisco I. Madero and the Cozamin deposits. The Madero deposit is hosted in thin-layered siliceouscarbonaceous units, with chlorite, calcite, and pyrite alteration that can be seen only underground. The Cozamin deposit occurs in veins hosted by the Chilitos Formation, andesites, phyllites, and siltstones. General vein trending is N 40° to 65° W dipping 65° to 75° NE, and the entire group of veins is known as the Mala Noche vein system. Good morning! Take the side road, San Luis Potosi-Mexico, to the east. 0.4 Turn left on Colorines street and take the San Luis-Mexico Highway to the west. 0.9 Jump into the Distribuidor Vial Benito Juarez and take the road San Luis Potosi-Matehuala to the north. 2.1 Turn left and follow the Boulevard Rio Santiago to the west. 2.6 Turn right on Fray Diego de la Magdalena Street. 1.1 To the right you'll see the Tangamanga local park, a Formula 3 racing course. Continue straight to Zacatecas by way of the Federal Highway no. 49. 4.1 Pass over the bridge of the Anillo Periferico Norte. 14.6 Route passes by cultivated areas and a series of small

Abstract Recent studies show that Late Palaeozoic Ice Age (LPIA) climate change broadly affected marine invertebrate faunas: glaciations decreased origination and extinction and long-term gradual global warming during the final deglaciation altered palaeocommunity composition. Carboniferous stratigraphy and palaeoecology in the Paganzo and Río Blanco basins of southwestern Gondwana (present-day Argentina) were studied in ordered to further determine how palaeocommunities were influenced by glacial and post-glacial processes during the LPIA. In the Paganzo Basin, the Guandacol Formation consisted of an ice-proximal to very ice-distal glaciomarine succession, while the Tupe Formation represented continental fluvial lowstand sedimentation interrupted by periodic marine incursions (estuary setting). In the Río Blanco Basin, the Río del Peñon Formation represents a shallowing-upwards coastal marine facies under the influence of wave and storm activity. Diversity and abundance data from northwestern Argentina reflects that ice-proximal environments proved physiologically stressful to organisms, limiting colonization to only opportunistic fauna. Following glaciation, the fauna of northwestern Argentina diversified and became increasingly ecologically complex during two marine transgressions in the Río Blanco Basin. It is interpreted that palaeocommunity establishment, composition and diversification in western Argentina during the LPIA was mostly dependent upon localized environmental conditions and palaeogeographic location.

New field mapping and bulk-rock geochemical investigations in the southern Klamath Mountains and central Sierran Foothills combined with previous structural, petrochemical, and geochronologic studies allow the distinction between three Triassic–Jurassic basaltic arcs built along the continental edge versus two roughly coeval basaltic complexes that formed farther off the Californian margin. The three Klamath Mountains arcs are: (1) The Hayfork Summit–Salmon River segment of the southern North Fork terrane, formed offshore as a sequence of interlayered chert, volcaniclastic strata and shale, and ocean island basalt (OIB), deposited on a mélanged and serpentinized basement containing blocks of 310- to 265-Ma mid-ocean ridge basalt (MORB). (2) Northward, the Sawyers Bar sector of the central North Fork terrane formed closer to the continental margin; this mafic arc originated at ca. 200–170 Ma as a stack of interdigitated island-arc tholeiites (IAT) and minor OIBs interstratified with, and largely overlying, distal turbidites derived from eastern Klamath terranes. (3) The currently farther outboard Rattlesnake Creek terrane consists of continent-sourced, Lower Jurassic metasedimentary quartzose strata interbedded with island-arc volcanic rocks; this near-shore section was laid down on older ophiolitic basement consisting of tectonized serpentinite and MORB blocks. The remaining two arcs are in the Sierran Foothills: (4) The offshore Peñon Blanco arc consists of cherty and volcaniclastic sedimentary strata interlayered with 200-Ma mafic volcanic-plutonic arc rocks, all resting on a 300-Ma ophiolitic basement; suturing against the structurally higher Mariposa Formation took place after deformation of the latter at ca. 150 Ma. (5) The Slate Creek complex, and possibly the Lake Combie, Owl Gulch, and Sullivan Creek entities, formed along the margin of North America; superjacent units consist chiefly of 207- to 170-Ma volcaniclastic, sedimentary, and arc volcanic rocks deposited on an ophiolitic mélange basement. Metamorphic belts of the central Klamath Mountains and Sierran Foothills evidently contain both near-shore and offshore oceanic arcs.