Work

Imaging Continental Rifting Structures From Eastern Gondwana Breakup by Full‐Waveform Inversion of Marine Wide‐Angle Seismic Data

Year: 2025

Type: article

Abstract: The Lord Howe Rise (LHR), a submerged continental fragment of Zealandia offshore eastern Australia, provides a rare opportunity to investigate the fine‐scale structure of a magma‐poor rifted margin. This study applies full waveform inversion (FWI) of 2D marine wide‐angle seismic data acquired with densely deployed ocean‐bottom seismometers with 800 m spacing, generating a high‐resolution P‐wave velocity model across the central LHR. The inversion reveals localized low‐velocity zones (LVZs) within fault‐bounded sedimentary depocenters, and a prominent low‐angle reflector interpreted as a possible décollement at greater depths. Unlike previous studies in this region, which primarily relied on conventional tomography and reflection data, our results resolve subtle velocity anomalies linked to fluid migration, tectonic fracturing, and diagenetic alteration. Low‐velocity zones exhibit reductions from ∼2.5 km/s to ∼2.1 km/s between ∼2.4 and 2.7 km depth, coinciding with enhanced porosity and opal‐CT precipitation. The possible décollement, observed at ∼6–8 km depth, dips gently and marks a mechanical decoupling horizon consistent with asymmetric rifting. These findings reveal previously unresolved features of post‐rift diagenesis, fluid pathways, and fault‐related strain partitioning within the LHR, offering new insights on the tectonic evolution of Zealandia. When placed within the broader tectonic evolution of Zealandia, the study emphasizes post‐rift overprints as primary controls on the observed seismic anomalies and demonstrates how imaged velocity anomalies can constrain fluid–rock interactions and basin evolution during continental breakup.

Source: Journal of Geophysical Research Solid Earth

DOI: 10.1029/2025jb032388

Authors: Mehmet Ali Uge, Brian Boston, Gou Fujie, Kazuya Shiraishi, Yasuyuki Nakamura, Shuichi Kodaira

Institutions: Japan Agency for Marine-Earth Science and Technology, Auburn University

Language: English

Topic: Geological and Geophysical Studies

Subfield: Geology

Field: Earth and Planetary Sciences

Domain: Physical Sciences

Open Access status: hybrid

Estimated APC paid: $4,070

Funders: Discovery Eye Foundation, Japan Agency for Marine-Earth Science and Technology