The Betic-Rif arc is one of the smallest and tightest orogenic arcs on Earth, and together with its extensional hinterland, the Alborán Domain, it formed between two colliding continents. The region provides examples of a range of tectonic processes that are not predictable from the rules of rigid-plate tectonics. The Alborán Domain reveals two stages of subduction and accretion, with different thermal histories and mechanisms of exhumation. The external Betic-Rif thrust belt illustrates four processes that create an arcuate orogen and a strongly divergent pattern of slip vectors: (a) the interaction between the westward moving Alborán Domain and the converging African and Iberian margins, (b) divergence in relative motion due to extension within the Alborán Domain, (c) slip partitioning onto strike-slip faults within the arc, and (d) vertical-axis rotations resulting from oblique convergence on the limbs of the arc.

Purpose Non-invasive imaging is central to hepatocellular carcinoma (HCC) diagnosis; however, conventional modalities are limited by smaller tumors and other chronic diseases that are often present in patients with HCC, such as cirrhosis. This pilot study evaluated the feasibility of (4S)-4-(3-[18F]fluoropropyl)-L-glutamic acid ([18F]FSPG) positron emission tomography (PET)/X-ray computed tomography (CT) to image HCC. [18F]FSPG PET/CT was compared to standard-of-care (SOC) magnetic resonance imaging (MRI) and CT, and [11C]acetate PET/CT, commonly used in this setting. We report the largest cohort of HCC patients imaged to date with [18F]FSPG PET/CT and present the first comparison to [11C]acetate PET/CT and SOC imaging. This study represents the first in a US HCC population, which is distinguished by different underlying comorbidities than non-US populations. Procedures xC− transporter RNA and protein levels were evaluated in HCC and matched liver samples from The Cancer Genome Atlas (n = 16) and a tissue microarray (n = 83). Eleven HCC patients who underwent prior MRI or CT scans were imaged by [18F]FSPG PET/CT, with seven patients also imaged with [11C]acetate PET/CT. Results xC− transporter RNA and protein levels were elevated in HCC samples compared to background liver. Over 50 % of low-grade HCCs and ~70 % of high-grade tumors exceeded background liver protein expression. [18F]FSPG PET/CT demonstrated a detection rate of 75 %. [18F]FSPG PET/CT also identified an HCC devoid of typical MRI enhancement pattern. Patients scanned with [18F]FSPG and [11C]acetate PET/CT exhibited a 90 and 70 % detection rate, respectively. In dually positive tumors, [18F]FSPG accumulation consistently resulted in significantly greater tumor-to-liver background ratios compared with [11C]acetate PET/CT. Conclusions [18F]FSPG PET/CT is a promising modality for HCC imaging, and larger studies are warranted to examine [18F]FSPG PET/CT impact on diagnosis and management of HCC. [18F]FSPG PET/CT may also be useful for phenotyping HCC tumor metabolism as part of precision cancer medicine.

The processes that drastically thinned and rapidly exhumed the Alborán Domain in southern Spain are poorly understood. Geological maps, cross-sections and a synthesis of previous work in the Alpujárride Complex provide a new structural framework for the Alborán Domain, with major revision of the previously defined lithotectonic units. Alborán continental lithosphere was buried and thickened in the Paleogene (D 1 ) and subsequently thinned during late-orogenic extension in the early Miocene. Regional patterns of stretching lineations and late recumbent folds record important spatiotemporal changes in the kinematics of extension. East-directed shear (D 2 ) is preserved in deep orogenic levels and thinned the crustal sequence during rapid exhumation and high-temperature metamorphism. North-directed shear (D 3 /D 4 ) is preserved in upper orogenic levels and reworked earlier structures during the later stages of exhumation and cooling. This large-scale switch in the direction of finite stretching resulted from the interaction between components of orogen-parallel (D 2 ) and orogen-perpendicular (D 3 /D 4 ) extension, and associated vertical and lateral gradients in strain. We provide a novel kinematic model for gravity-driven extensional collapse of the Alborán Domain, compatible with both westward motion of the Alborán Domain relative to the Iberian margin and subsequent northward extensional flow and emplacement of Alborán lithosphere onto the Iberian margin. Supplementary material: A list of sample names, coordinates and descriptions, plus a Google Earth .kmz file of sample locations is available at https://doi.org/10.6084/m9.figshare.5508643 . A geological sketch map of the Sierra de las Estancias, indicating the trend of stretching lineations in the Alpujárride Complex and location of major geological boundaries is available at https://doi.org/10.6084/m9.figshare.5513398 .

On Earth, microorganisms commonly enhance mineral precipitation and mediate mineralogical and chemical compositions of resulting deposits, particularly at spring systems. However, preservation of any type of microbial fossil or chemical or textural biosignature depends on the degree of alteration during diagenesis and factors such as exposure to diagenetic fluids. Little is known about the transformation of biosignatures during diagenesis over geologic time. Ten Mile Graben, Utah, USA, hosts a cold spring system that is an exceptional site for evaluation of diagenetic alteration of biosignatures because of the presence of modern springs with actively precipitating microbial mats and a series of progressively older tufa terraces (<400 ka) preserved in the area from the same spring system. A previously undescribed Jurassic laminated carbonate unit within the upper part of the Brushy Basin Member of the Morrison Formation is also exposed in Ten Mile Graben. This research characterizes the geology of these modern and Quaternary saline, Fe-undersaturated, circumneutral Ten Mile Graben cold springs and provides the first description in the literature of the Jurassic Brushy Basin Member of the Morrison Formation carbonate deposit. Taphonomy of microbial fossils is characterized by scanning electron microscopy (SEM). The data highlight two distinct methods of biosignature formation: (1) precipitation of minerals from an undersaturated solution owing to metabolic activity of the cells and (2) mineral precipitation on charged cell surfaces that produce distinctive microbial trace fossils. Although diagenesis can destroy or severely degrade biosignatures, particularly microbial fossils, some fossils and trace fossils are preserved because entombment by Ostwald ripening limits diagenetic alteration. Recognizing spring-fed, biogenic tufas is crucial for astrobiological research and the search for life on Mars. Key Words: Biosignatures-Taphonomy-Diagenesis-Carbonates-Hot springs. Astrobiology 17, 216-230.

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