Schlindwein, Vera

Preferred name

Schlindwein, Vera

Official Name

Schlindwein, Vera

ORCID

0000-0001-5570-2753

GND

1276869347

Now showing 1 - 5 of 5

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Tectonic and lithospheric controls on arctic hydrothermal vent systems constrained by deep-learning enabled microseismicity catalogs
(2026-03-02)
Pilot, Matthias
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Perez Gussinyé, Marta
;
Reiss Miriam Christina
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Schlindwein, Vera
As the Earth’s tectonic plates diverge, new oceanic crust forms along mid-ocean ridges, but the mechanisms of crustal accretion change fundamentally with varying spreading rates. At ultraslow spreading ridges (<20 mm/yr), limited melt supply produces a highly heterogeneous lithosphere, where melt-rich volcanic centers alternate with non-volcanic segments shaped by tectonic extension and long-lived detachment faults. Despite their sparse melt supply, these ridges host abundant hydrothermal vent fields, demonstrating that vigorous hydrothermal circulation can persist even where tectonic processes dominate. However, the subseafloor processes influencing these systems remain largely unresolved, particularly along the sparsely surveyed Arctic mid-ocean ridges (AMOR). Clarifying the interplay of tectonic faulting, crustal permeability structure, and transient magmatic activity is therefore essential for understanding what controls hydrothermal systems at ultraslow spreading ridges. Microearthquakes provide key constraints on active faulting and brittle deformation, making them an effective tool for assessing tectonic controls on hydrothermal systems. This thesis analyzes data from two year-long ocean bottom seismometer (OBS) deployments around two Arctic hydrothermal vent fields: Loki’s Castle, the first visually confirmed vent field along the AMOR, and Aurora, the first visually confirmed vent field beneath the perennial Arctic sea ice. Both sites host >300 °C black smoker vents on basaltic mounds but are situated in contrasting tectonic settings. Loki’s Castle lies on an axial volcanic ridge where the Mohns and Knipovich Ridge intersect, in an area of pronounced across-axis asymmetry expressed by magmatic accretion in the east and tectonic accretion in the west. Aurora is situated at the intersection of the magmatically robust Western Volcanic Zone (WVZ) and the non-volcanically spreading Lena Trough, and despite its position on a basaltic mound, its vent fluid chemistry indicates interaction with ultramafic rocks at depth. To process the large number of microearthquakes recorded from both OBS deployments, I developed a workflow that applies modern deep-learning algorithms to OBS datasets, producing robust earthquake catalogs despite the limited station coverage and the noisy marine environment. While results show that automatically compiled catalogs can reproduce the main seismicity patterns of a manually compiled reference subset, careful evaluation of available algorithms is necessary to ensure reliable results. The amount of required manual re-evaluation can then be tailored to the dataset and scientific goals. Application of this workflow to the two OBS datasets revealed fundamentally different relationships between tectonic deformation and hydrothermal circulation. At Loki’s Castle, seismicity is concentrated on the western rift valley flank along an emerging detachment fault, indicating that plate divergence is accommodated away from the vent field atop the axial volcanic ridge. This spatial decoupling suggests that the hydrothermal system is rather sustained by a localized magmatic heat source beneath the ridge, while the emerging detachment fault more likely only influences the broader fluid pathways. At Aurora, in contrast, seismicity is distributed beneath the vent field, and the lack of evidence for a localized heat source directly below implies that circulation is maintained by a persistent, fracture-controlled permeability system within a transitioning spreading environment. The microseismicity delineates a shift from magmatic to non-volcanic spreading from the WVZ toward Lena Trough, and a thickening aseismic layer below the vent field likely reflects ultramafic lithologies at depth. Although both sites exhibit basalt-hosted high-temperature venting, they are sustained by fundamentally different subsurface processes controlled by their local tectonic settings, melt supply, and lithospheric structure. More broadly, by applying modern deep-learning methods to the first long-term OBS datasets from hydrothermal vent fields along ultraslow spreading ridges, this thesis advances our understanding of how lithospheric architecture and spreading style influence hydrothermal systems in melt-poor and tectonically dominated environments.
doctoral thesis
20 43
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Implications of the neotectonics around the Laptev Sea Rift as a result from (micro-) seismicity analysis
(2024-11-22)
Ploetz, Aline
;
Schweitzer, Johannes
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Schlindwein, Vera
;
Schlindwein, Vera
The Laptev Sea Rift offers an outstanding opportunity to study continental rifting. At the edge of the Laptev Sea, the ultra-slow spreading Gakkel Ridge encounters the continental slope, with the divergent motion continuing on the continent within the Laptev Sea Rift. Due to the isolated location of this unique region at the northern edge of the Arctic Circle in Siberia, geophysical investigations are still relatively rare. The study of earthquakes is a suitable method for exploring geodynamic processes. However, the global network of permanent seismic stations is relatively sparse above the Arctic Circle, resulting in only a vague understanding of the (micro-)seismic activity in the Laptev Sea region, as weaker seismic events simply cannot be detected. The global earthquake catalogue (until 2018) demonstrates a significant distribution of earthquakes clearly defined along the axes of the Gakkel Ridge. In the transition zone, where the ridge meets the continent, a decrease in activity is observed, dispersing into a wider area to the south. In this study, earthquake data recorded at stations of a local, temporary network and arrays were analysed. The data set spans a period of nine months, from August 2016 to April 2017. This study focuses on the neotectonic context to address whether the Laptev Sea Rift is still active and whether the rift region can be defined as a separate tectonic block, such as a microplate.
doctoral thesis
75 321
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Unsupervised deep machine learning methods to discriminate icequakes in seismological data from Neumayer Station, Antarctica
(2024-03-05)
Kinzel, Louisa
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Stark, Hans-Georg
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Maaß, Peter
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Fromm, Tanja
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Schlindwein, Vera
Unsupervised machine learning methods are gaining attention in the seismological community as more and larger datasets of continuous waveforms are collected, since they tackle the chal- lenging task of learning without using hand-labelled data. In this thesis, we present some neural network approaches to the task of unsupervised learning, and apply them to discriminate and cluster different seismological events, including icequakes and earthquakes. We focus mainly on contrastive learning, which has recently been showing great success in the field of computer vision and other domains, and we transfer these methods to the domain of seismology. We implemented and tested data augmentation strategies for seismological data, and applied the contrastive learning method SimCLR as well as the deep clustering method DEC. For this pur- pose, we created and partially labelled different datasets containing various waveforms including many icequakes detected by an STA/LTA algorithm on continuous waveform recordings from the geophysical obervatory at Neumayer station, Antarctica. We demonstrate the effectiveness of our approach using quantitative evaluation on the labelled dataset as well as qualitative evaluation of the clustering on a larger unlabelled dataset.
doctoral thesis
329 216
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Ultraslow Spreading Processes - A Microseismicity Study of the Knipovich Ridge
(2022-02-10)
Meier, Michaela
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Haberland, Christian
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Schlindwein, Vera
;
Schlindwein, Vera
Along the global mid-ocean ridge system, new seafloor is constantly formed as tectonic plates drift apart. When spreading rate is reduced to less than 20 mm/yr the spreading dynamics change drastically and thereby the entire appearance of these ultraslow spreading ridges differs from faster spreading ridges. Melt is unevenly distributed such that volcanic centers receive more melt than the ridge on average does. Amagmatic segments in between are the melt-poor counterpart. The process of melt focusing is suggested to guide melt along the lithosphere – asthenosphere boundary from amagmatic segments towards volcanic centers. Until now, the processes acting at ultraslow spreading ridges are not completely understood. Key questions are the scale of melt focusing and how melt is extracted at the volcanic centers, the role of detachment faults and the extent of rock alteration. With a microseismicity study on the scale of an entire segment, spanning from one volcanic center to another, these questions could be addressed. The unique microseismicity study was conducted at the Knipovich Ridge, that is a very oblique, ultraslow spreading ridge and part of the Arctic Ridge System. The ocean bottom seismometer network of in total 30 stations was deployed for around one year along 160 km of the rift axis. It covered the Logachev volcanic center, which is the major volcanic center of the Knipovich Ridge, and a second volcanic center south of it. For the recorded data I used automatic earthquake detection and picking of P- and S-phases with a subsequent manual pick check. In this way I extracted in total 14401 earthquakes from the recorded data in the study area. The earthquakes in this comprehensive earthquake catalog were located with different algorithms. 8435 earthquakes with a maximum depth error and Smajor of 5 km and a RMS of 0.4 s were classified as reliably located and used for further interpretations. I determined fault plane solutions for 44 events. Furthermore, I used the earthquakes for a local earthquake tomography of the Logachev area and the entire area covered by the network. From this extensive, unique dataset I found a varying segment-scale pattern of seismicity. The maximum depth of seismicity marks an undulating boundary of the mechanical lithosphere. It is shallowest at the Logachev volcanic center and deepens away from it for 70 km. Thus, I find new evidence that melt focusing may act over distances of 70 km to accumulate the above average melt volumes at volcanic centers. It can therefore be considered an essential mechanism shaping ultraslow spreading ridges. The different spreading styles, magmatic and amagmatic, caused by the uneven melt supply, can be distinguished by their characteristic microseismicity patterns. Magmatic sections are, besides shallower maximum depth of faulting, characterized by shallow seismicity, that is absent in suggested amagmatic sections. At these amagmatic sections, I infer from yield strength envelopes rock alteration reaching 9 km below the seafloor. The differing magmatic section hosts a partial melt area with its top at around 10 km below the sea level underneath the Logachev volcanic center. This is indicated by high Vp/Vs-ratios and low S-velocities from the local earthquake tomography. Elevated temperatures around the partial melt area lead to more ductile behavior resulting in a gap in the seismicity. Directly above the partial melt area high earthquake swarm activity maps the ascent path of melt to the surface. Lateral feeding as observed at orthogonal spreading segments is prevented by the obliquity of the Knipovich Ridge. Hence, I conclude that melt is redistributed and extracted depending on the crustal structure of the ridge. The obliquity of the Knipovich Ridge also affects the transform motion that seems to be hosted on small fault planes producing too small seismicity to be recorded by the KNIPAS network. Additionally, seismicity patterns of active detachment faults are not observed. This stands in contrast to the Southwest Indian Ridge, where detachment faults are a common feature. Consequently, I find that detachment faults are not ubiquitous at ultraslow spreading ridges. With the first ocean bottom seismometer survey on ultraslow spreading ridges, that covers entire spreading segments, this study yields an important contribution in understandig spreading processes and dynamics. It gives insights how melt is distributed along the melt poorest endmembers of the mid-ocean ridge system and how the interplay of magmatic and tectonic activity shapes the lithospheric structure.
doctoral thesis
338 207
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Seismicity of ultraslow spreading mid-ocean ridges at local, regional and teleseismic scales: A case study of contrasting segments
(2012-02-15)
Läderach, Christine
;
Spiegel, Cornelia
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Schlindwein, Vera
;
Schlindwein, Vera
The main representatives of ultraslow spreading ridges are the Arctic Ridge System (ARS) and the Southwest Indian Ridge (SWIR). As earthquakes indicate active crustal accretion, monitoring the seismicity provides information about the mechanical state of the lithosphere. The Lena Trough, part of the ARS, spreads obliquely and amagmatic. I relocalized the globally detected earthquakes to show the spatial distribution of the seismicity along the rift axis. During two surveys, our working group recorded the microseismicity of Lena Trough with seismic arrays deployed on ice floes. The second case study concerns the magmatic Orthogonal Supersegment of the SWIR. I accessed the regional dataset of the Neumayer seismic array in Antarctica lying in a distance of ~2100 km to the study area. The dataset contains 743 earthquakes and clearly shows four swarms occurring at an assumed volcanic centre. The new datasets allow a comprehensive evaluation lowering the detection threshold compared to the global station network. Active accretion episodes can be monitored in greater detail showing the spreading mechanisms at contrasting amagmatic and magmatic ridge segments.
doctoral thesis
565 159

Schlindwein, Vera

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