Fig.1

The location(a) and structural units(b) of the Halahatang oilfield, Tarim Basin"

Fig.2

Sequence stratigraphic framework of the Ordovician in the Halahatang area of the Tabei Uplift at the end of Silurian (see Fig. 1 for the location of profile A—A′, modified from Si Chunsong et al.[21])"

Fig.3

Composite stratigraphic column of layers in Well B1 of the Halahatang oilfield, Tarim Basin"

Fig.4

Schematic diagram showing the near-surface meteoric karstification model (modified from Loucks[13])"

Fig.5

A block diagram showing the collapse and filling of a single channel cave(modified from Loucks[13])"

Fig.6

N-S seismic section crossing Well B1 in the Halahatang oilfield, Tarim Basin (flattened on top of the Sangtamu Formation, see Fig. 1 for the location of profile A—B)"

Fig.7

Topography of the Ordovician Lianglitage top unconformity in the Halahatang oilfield, Tarim Basin"

Fig.8

Characteristics of collapsed paleo-cave section depicted by core and thin section observations and log interpretation in Well A1 of the Halahatang oilfield, Tarim Basin"

Fig.9

RMS amplitude and variance fusion map of the Lianglitage Formation in part of the Halahatang oilfield, Tarim Basin"

Fig.10

Plane and section views of the seismic profiles showing the collapsed karst cave system in the Lianglitage Formation in the Halahatang oilfield, Tarim Basin"

Fig.11

A collapsed karst cave system protruding into the slope of the Lianglitage Formation of the Halahatang oilfield, Tarim Basin"

Fig.12

Plane view of the relationship between the paleo-karst cave system and previously possible regional fault systems in block 4 of the Halahatang oilfield, Tarim Basin"

Fig.13

Seismic section showing the relationship between the surficial fluvial systems and the subsurface karst cave systems in the Halahatang oilfield, Tarim Basin(see Fig. 9 for the location of profile C—C′, flattened on top of the Lower Yingshan Formation)"