ALBERT

Description: Highlights • New geophysical data and samples redefine submarine volcanism in Sicilian Channel. • Three dominant bands of volcanism are distinguished. • Ancient, eroded structures aligned at 120° are tied to faulted banks in the north. • Younger band of similarly aligned volcanism in the south is linked to grabens. • Youngest structures comprise small, dispersed volcanoes with distinct orientation. Abstract The origin and role of volcanism in continental rifts remains poorly understood in comparison to other volcano-tectonic settings. The Sicilian Channel (central Mediterranean Sea) is largely floored by continental crust and represents an area affected by pronounced crustal extension and strike-slip tectonism. It hosts a variety of volcanic landforms closely associated with faults, which can be used to better understand the nature and distribution of rift-related volcanism. A paucity of appropriate seafloor data in the Sicilian Channel has led to uncertainties regarding the location, volume, sources and timing of submarine volcanism. To improve on this situation, we use newly acquired geophysical data (multibeam echosounder and magnetic data, sub-bottom profiles) and dredged seafloor samples to: (i) re-assess the evidence for submarine volcanism in the Sicilian Channel and define its spatial pattern, (ii) infer the relative age and style of magmatism, and (iii) relate this to the dominant tectonic structures in the region. Quaternary rift-related volcanism has been focused at Pantelleria and Linosa, at the northwest boundaries of their respective NW-SE trending grabens. Subsidiary and older volcanic sites potentially occur at the Linosa III and Pantelleria SE seamounts, collectively representing the only sites of recent volcanism that can be directly related to the main rift process. These long-lived polygenetic volcanic landforms have been shaped by magmatism that is directly correlated with extensional faulting and buried igneous bodies. Older volcanic landforms, sharing a similar scale and alignment, occur to the north at Nameless Bank and Adventure Bank. These deeply eroded volcanoes have likely been inactive since the Pliocene and are probably related to earlier stages of crustal thinning and underlying feeder structures in the northern region of the Sicilian Channel. Along a similar alignment, Pinne Bank, SE Pinne Bank and Cimotoe in the northern Sicilian Channel lack a surface volcanic signature but are associated with intrusive bodies or deeply buried volcanic rock masses. Terrible Bank, in the same region, also shows evidence of ancient, polygenetic magmatism, but was subject to significant erosion and lacks a prominent alignment. The much younger volcanism at Graham Volcanic Field and along the northern Capo-Granitola-Sciacca Fault Zone differs markedly from that observed in the other study areas. Here, the low-volume and scattered volcanic activity is driven by shallow-water mafic magma eruptions, which gave rise to small individual cones. These sites are associated with large fault structures away from the main rift axis and may have a distinct magmatic origin. Dispersed active fluid venting occurs across both ancient and young volcanic sites in the region and is directly associated with shallow magmatic bodies within tectonically-controlled basins. Our study provides the foundation for an updated tectonic and magmatic framework for the Sicilian Channel, and for future detailed chronological and geochemical assessment of the sources and evolution of magmatic processes in the region.

Description: Highlights • Alkaline magmas of the TLTF island chain result from a subduction-modified mantle source and two-stage partial melting. • The role of mantle source and parental melt composition for high Cu-Au mineral potentials is important but limited. • A shallow crustal magma reservoir is key for epithermal ore formation. Abstract The Tabar-Lihir-Tanga-Feni (TLTF) island chain in northeastern Papua New Guinea formed by tectonic and alkaline to shoshonitic magmatic activity since the Pliocene. Several volcanic centers are Cusingle bondAu mineralized including the world-class Ladolam Au deposit and Conical Seamount south of Lihir. The latter has been recognized as a juvenile analogue to the Ladolam deposit located on-shore. Whereas the mineralization at Conical Seamount is reasonably well studied, the specific magmatic processes that promote epithermal mineralization at this seamount but not at others are poorly understood. Here, we present new petrological and geochemical data from Conical Seamount, and compare them with those from the barren (unmineralized) Edison, Tubaf and New World seamounts nearby. We focus on whole rock compositions and major and trace element analysis of melt inclusions and minerals including clinopyroxene, sulfide and magnetite. We combine our observations with modelled constraints on mantle source composition and partial melting as well as magma evolution. A first-stage melting leaves a residual mantle source enriched in Au. Second-stage melting of a previously subduction-metasomatized mantle generally promotes the transfer and concentration of metals and volatiles in the ascending melts. These magmas are unlikely to control ore formation as all seamounts show evidence for similar mantle sources and parental melt composition. However, the presence of a shallow crustal magma chamber is unique to Conical Seamount. It is characterized by frequent melt replenishments and extensive magma fractionation leading to sulfide and magmatic volatile saturation. These specific magma chamber processes lead to the pre-enrichment of the magma in chalcophile elements including Au, while sulfide saturation coeval with magmatic volatile exsolution provide the way for an effective Au transfer from the magmatic to the epithermal system.

Description: Raw data acquired by position sensors on board RV METEOR during expedition M196 were processed to receive a validated master track which can be used as reference of further expedition data. During M196 the motion reference unit Kongsberg SeaTex AS MRU-5 combined with Kongsberg SeaTex AS Seapath 320 and two C and C Technologies GPS receivers C-NAV3050 were used as navigation sensors. Data were downloaded from DAVIS SHIP data base (https://dship.bsh.de) with a resolution of 1 sec. Processing and evaluation of the data is outlined in the data processing report. Processed data are provided as a master track with 1 sec resolution derived from the position sensors' data selected by priority and a generalized track with a reduced set of the most significant positions of the master track.

Description: Passive acoustic monitoring (PAM) data were collected by recorder SV1019 of type Sono.Vault (manufactured by develogic GmbH, Hamburg, Germany) at 20.9757 ° S, 5.9845 ° E, mooring AWI247-3, in the eastern Atlantic Ocean off Namibia. During a deployment period from November 2012 to November 2014, passive acoustic data were collected from November 2012 to May 2013 (recording period) by SV1019 off Namibia. The recorder was moored at 736 m depth and scheduled to record continuously at a sample rate of 5,333 Hz. Further details about the data acquisition and processing of this data set can be found in the accompanying metadata file (see Additional metadata) as well as the data processing report (see Data Processing Report). Passive acoustic data archived here represent data processing Level 1+, according to the standards defined in the associated Standard Operation Procedure (SOP) Glossary (Thomisch et al. 2023a). Further information on data processing with regard to data preparation and standardization can be found in the associated SOP Part 1: Data preparation and standardization (Thomisch et al. 2023b).

Description: Passive acoustic monitoring (PAM) data were collected by recorder SV1008 of type Sono.Vault (manufactured by develogic GmbH, Hamburg, Germany) at 20.9633 ° S, 5.9767 ° E, mooring AWI247-2, in the eastern Atlantic Ocean off Namibia. During a deployment period from November 2011 to November 2012, passive acoustic data were collected from November 2011 to August 2012 (recording period) by SV1008 off Namibia. The recorder was moored at 741 m depth and scheduled to record continuously at a sample rate of 5,333 Hz. Further details about the data acquisition and processing of this data set can be found in the accompanying metadata file (see Additional metadata) as well as the data processing report (see Data Processing Report). Passive acoustic data archived here represent data processing Level 2+ (see the associated data processing report), deviating from Standard Operation Procedure (SOP) Glossary (Thomisch et al. 2023a). Further information on data processing with regard to data preparation and standardization can be found in the associated SOP Part 1: Data preparation and standardization (Thomisch et al. 2023b).

Description: Passive acoustic monitoring (PAM) data were collected by recorder SV1005 of type Sono.Vault (manufactured by develogic GmbH, Hamburg, Germany) at 69.005° S, 6.9815° W, mooring AWI244-2, in the Weddell Sea, Atlantic sector of the Southern Ocean. During a deployment period from December 2010 to December 2012, passive acoustic data were collected from December 2010 to January 2011 (recording period) by SV1005 as part of the Hybrid Antarctic Float Observing System (HAFOS) in the Weddell Sea. The recorder was moored at 1003 m depth and scheduled to record continuously at a sample rate of 5,333 Hz. Further details about the data acquisition and processing of this data set can be found in the accompanying metadata file (see Additional metadata) as well as the data processing report (see Data Processing Report). Passive acoustic data archived here represent data processing Level 2+, deviating from the standards defined in the associated Standard Operation Procedure (SOP) Glossary (Thomisch et al. 2023a). Further information on data processing with regard to data preparation and standardization can be found in the associated SOP Part 1: Data preparation and standardization (Thomisch et al. 2023b).

Description: Photomicrographs of representative mineralogy are here presented for each unit defined in our study. Unit A is dominated by quartz and feldspar whereas clay minerals, clinopyroxene and micas are in minor proportions (S4.1 and S4.2). Quartz, especially polycrystalline quartz, is dominant within the Unit B whereas micas and clinopyroxene are low in abundance (S4.3 and S4.4). Unit C is characterized by a high content in clay minerals as well as feldspar and monocrystalline quartz (S4.5). Unit D is characterized by a high content of polycrystalline quartz (chert) and feldspar (S4.6 and S4.7).

Description: U-Pb zircon age dating was applied on U-channel samples (30cc) that were collected from sandy deposits in cores from IODP Site C0024 (one sample; frontal Nankai accretionary Prism), ODP Site 1177 (two samples; Western Shikoku Basin) and IODP sites C0011 (three samples) and C0012 (one sample; Eastern Shikoku Basin). Detrital zircon U-Pb ages were measured using the London Thermochronology Research Group facilities at UCL based on a New Wave Nd: YAG 213 nm laser ablation system coupled plasma-mass spectrometry. Real time U-Pb were processed using GLITTER data reduction software. Repeated measurements of external zircon standard Plesovice (TIMS reference 337.13 +/-0.37 Myr ago) and NIST 612 silicate glass were used to correct for instrumental mass bias and depth-dependent inter-element fractionation of Pb, Th, and U. 206Pb/238U ages are used for those grain younger than 1 Ga, and for zircon grains older than 1,000 Ma we used the 207Pb/206Pb ages to determine the crystallization age. To better constrain the sediment provenance along the Nankai subduction zone, we integrated published U-Pb zircon age to our study. These include (1) potential sediment sources, e.g., Nagara, Yodo, Tenryu, Kiso and Fuji rivers from Clift et al. (2013) (https://doi.pangaea.de/10.1002/tect.20033), the Yangtze and Yellow rivers from Huang et al. (2020) (https://doi.pangaea.de/10.3390/min10050398), the Shimanto Complex from Shibata et al. (2008) (https://doi.org/10.1111/j.1440-1738.2008.00626.x) and the Sanbagawa Belt from Tsutsumi et al. (2009) (https://doi.org/10.2465/jmps.080416) and (2) published zircon ages from the frontal accretionary prism ((ODP sites 1176 and 1177 and IODP sites C0006E and C0007E; Clift et al., 2013) (https://doi.pangaea.de/10.1002/tect.20033).

Description: Ternary diagrams are commonly used in Earth Sciences to represent numerical data as ratios of three components. For our study, ternary provenance diagrams were created in Microsoft Excel directly from the raw point-count data of sand samples from IODP sites C0002N and C0002P (presented in doi:10.1594/PANGAEA.969334). Raw point-count data were recalculated as volumetric proportions by summing up quartzose, feldspar and lithic fragment framework constituents. Other grains identified in the point counting were excluded from these calculations but were retained for later use in stratigraphic correlation.